v4.19.13 snapshot.
diff --git a/mm/mmap.c b/mm/mmap.c
new file mode 100644
index 0000000..f7cd9cb
--- /dev/null
+++ b/mm/mmap.c
@@ -0,0 +1,3709 @@
+/*
+ * mm/mmap.c
+ *
+ * Written by obz.
+ *
+ * Address space accounting code <alan@lxorguk.ukuu.org.uk>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/backing-dev.h>
+#include <linux/mm.h>
+#include <linux/vmacache.h>
+#include <linux/shm.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/syscalls.h>
+#include <linux/capability.h>
+#include <linux/init.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/personality.h>
+#include <linux/security.h>
+#include <linux/hugetlb.h>
+#include <linux/shmem_fs.h>
+#include <linux/profile.h>
+#include <linux/export.h>
+#include <linux/mount.h>
+#include <linux/mempolicy.h>
+#include <linux/rmap.h>
+#include <linux/mmu_notifier.h>
+#include <linux/mmdebug.h>
+#include <linux/perf_event.h>
+#include <linux/audit.h>
+#include <linux/khugepaged.h>
+#include <linux/uprobes.h>
+#include <linux/rbtree_augmented.h>
+#include <linux/notifier.h>
+#include <linux/memory.h>
+#include <linux/printk.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/moduleparam.h>
+#include <linux/pkeys.h>
+#include <linux/oom.h>
+
+#include <linux/uaccess.h>
+#include <asm/cacheflush.h>
+#include <asm/tlb.h>
+#include <asm/mmu_context.h>
+
+#include "internal.h"
+
+#ifndef arch_mmap_check
+#define arch_mmap_check(addr, len, flags) (0)
+#endif
+
+#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
+const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
+const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
+int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
+#endif
+#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
+const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
+const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
+int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
+#endif
+
+static bool ignore_rlimit_data;
+core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
+
+static void unmap_region(struct mm_struct *mm,
+ struct vm_area_struct *vma, struct vm_area_struct *prev,
+ unsigned long start, unsigned long end);
+
+/* description of effects of mapping type and prot in current implementation.
+ * this is due to the limited x86 page protection hardware. The expected
+ * behavior is in parens:
+ *
+ * map_type prot
+ * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
+ * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
+ * w: (no) no w: (no) no w: (yes) yes w: (no) no
+ * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
+ *
+ * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
+ * w: (no) no w: (no) no w: (copy) copy w: (no) no
+ * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
+ *
+ * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
+ * MAP_PRIVATE:
+ * r: (no) no
+ * w: (no) no
+ * x: (yes) yes
+ */
+pgprot_t protection_map[16] __ro_after_init = {
+ __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
+ __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
+};
+
+#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
+static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
+{
+ return prot;
+}
+#endif
+
+pgprot_t vm_get_page_prot(unsigned long vm_flags)
+{
+ pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
+ (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
+ pgprot_val(arch_vm_get_page_prot(vm_flags)));
+
+ return arch_filter_pgprot(ret);
+}
+EXPORT_SYMBOL(vm_get_page_prot);
+
+static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
+{
+ return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
+}
+
+/* Update vma->vm_page_prot to reflect vma->vm_flags. */
+void vma_set_page_prot(struct vm_area_struct *vma)
+{
+ unsigned long vm_flags = vma->vm_flags;
+ pgprot_t vm_page_prot;
+
+ vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
+ if (vma_wants_writenotify(vma, vm_page_prot)) {
+ vm_flags &= ~VM_SHARED;
+ vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
+ }
+ /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */
+ WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
+}
+
+/*
+ * Requires inode->i_mapping->i_mmap_rwsem
+ */
+static void __remove_shared_vm_struct(struct vm_area_struct *vma,
+ struct file *file, struct address_space *mapping)
+{
+ if (vma->vm_flags & VM_DENYWRITE)
+ atomic_inc(&file_inode(file)->i_writecount);
+ if (vma->vm_flags & VM_SHARED)
+ mapping_unmap_writable(mapping);
+
+ flush_dcache_mmap_lock(mapping);
+ vma_interval_tree_remove(vma, &mapping->i_mmap);
+ flush_dcache_mmap_unlock(mapping);
+}
+
+/*
+ * Unlink a file-based vm structure from its interval tree, to hide
+ * vma from rmap and vmtruncate before freeing its page tables.
+ */
+void unlink_file_vma(struct vm_area_struct *vma)
+{
+ struct file *file = vma->vm_file;
+
+ if (file) {
+ struct address_space *mapping = file->f_mapping;
+ i_mmap_lock_write(mapping);
+ __remove_shared_vm_struct(vma, file, mapping);
+ i_mmap_unlock_write(mapping);
+ }
+}
+
+/*
+ * Close a vm structure and free it, returning the next.
+ */
+static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
+{
+ struct vm_area_struct *next = vma->vm_next;
+
+ might_sleep();
+ if (vma->vm_ops && vma->vm_ops->close)
+ vma->vm_ops->close(vma);
+ if (vma->vm_file)
+ fput(vma->vm_file);
+ mpol_put(vma_policy(vma));
+ vm_area_free(vma);
+ return next;
+}
+
+static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags,
+ struct list_head *uf);
+SYSCALL_DEFINE1(brk, unsigned long, brk)
+{
+ unsigned long retval;
+ unsigned long newbrk, oldbrk;
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *next;
+ unsigned long min_brk;
+ bool populate;
+ LIST_HEAD(uf);
+
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
+#ifdef CONFIG_COMPAT_BRK
+ /*
+ * CONFIG_COMPAT_BRK can still be overridden by setting
+ * randomize_va_space to 2, which will still cause mm->start_brk
+ * to be arbitrarily shifted
+ */
+ if (current->brk_randomized)
+ min_brk = mm->start_brk;
+ else
+ min_brk = mm->end_data;
+#else
+ min_brk = mm->start_brk;
+#endif
+ if (brk < min_brk)
+ goto out;
+
+ /*
+ * Check against rlimit here. If this check is done later after the test
+ * of oldbrk with newbrk then it can escape the test and let the data
+ * segment grow beyond its set limit the in case where the limit is
+ * not page aligned -Ram Gupta
+ */
+ if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
+ mm->end_data, mm->start_data))
+ goto out;
+
+ newbrk = PAGE_ALIGN(brk);
+ oldbrk = PAGE_ALIGN(mm->brk);
+ if (oldbrk == newbrk)
+ goto set_brk;
+
+ /* Always allow shrinking brk. */
+ if (brk <= mm->brk) {
+ if (!do_munmap(mm, newbrk, oldbrk-newbrk, &uf))
+ goto set_brk;
+ goto out;
+ }
+
+ /* Check against existing mmap mappings. */
+ next = find_vma(mm, oldbrk);
+ if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
+ goto out;
+
+ /* Ok, looks good - let it rip. */
+ if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0)
+ goto out;
+
+set_brk:
+ mm->brk = brk;
+ populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
+ up_write(&mm->mmap_sem);
+ userfaultfd_unmap_complete(mm, &uf);
+ if (populate)
+ mm_populate(oldbrk, newbrk - oldbrk);
+ return brk;
+
+out:
+ retval = mm->brk;
+ up_write(&mm->mmap_sem);
+ return retval;
+}
+
+static long vma_compute_subtree_gap(struct vm_area_struct *vma)
+{
+ unsigned long max, prev_end, subtree_gap;
+
+ /*
+ * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
+ * allow two stack_guard_gaps between them here, and when choosing
+ * an unmapped area; whereas when expanding we only require one.
+ * That's a little inconsistent, but keeps the code here simpler.
+ */
+ max = vm_start_gap(vma);
+ if (vma->vm_prev) {
+ prev_end = vm_end_gap(vma->vm_prev);
+ if (max > prev_end)
+ max -= prev_end;
+ else
+ max = 0;
+ }
+ if (vma->vm_rb.rb_left) {
+ subtree_gap = rb_entry(vma->vm_rb.rb_left,
+ struct vm_area_struct, vm_rb)->rb_subtree_gap;
+ if (subtree_gap > max)
+ max = subtree_gap;
+ }
+ if (vma->vm_rb.rb_right) {
+ subtree_gap = rb_entry(vma->vm_rb.rb_right,
+ struct vm_area_struct, vm_rb)->rb_subtree_gap;
+ if (subtree_gap > max)
+ max = subtree_gap;
+ }
+ return max;
+}
+
+#ifdef CONFIG_DEBUG_VM_RB
+static int browse_rb(struct mm_struct *mm)
+{
+ struct rb_root *root = &mm->mm_rb;
+ int i = 0, j, bug = 0;
+ struct rb_node *nd, *pn = NULL;
+ unsigned long prev = 0, pend = 0;
+
+ for (nd = rb_first(root); nd; nd = rb_next(nd)) {
+ struct vm_area_struct *vma;
+ vma = rb_entry(nd, struct vm_area_struct, vm_rb);
+ if (vma->vm_start < prev) {
+ pr_emerg("vm_start %lx < prev %lx\n",
+ vma->vm_start, prev);
+ bug = 1;
+ }
+ if (vma->vm_start < pend) {
+ pr_emerg("vm_start %lx < pend %lx\n",
+ vma->vm_start, pend);
+ bug = 1;
+ }
+ if (vma->vm_start > vma->vm_end) {
+ pr_emerg("vm_start %lx > vm_end %lx\n",
+ vma->vm_start, vma->vm_end);
+ bug = 1;
+ }
+ spin_lock(&mm->page_table_lock);
+ if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
+ pr_emerg("free gap %lx, correct %lx\n",
+ vma->rb_subtree_gap,
+ vma_compute_subtree_gap(vma));
+ bug = 1;
+ }
+ spin_unlock(&mm->page_table_lock);
+ i++;
+ pn = nd;
+ prev = vma->vm_start;
+ pend = vma->vm_end;
+ }
+ j = 0;
+ for (nd = pn; nd; nd = rb_prev(nd))
+ j++;
+ if (i != j) {
+ pr_emerg("backwards %d, forwards %d\n", j, i);
+ bug = 1;
+ }
+ return bug ? -1 : i;
+}
+
+static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
+{
+ struct rb_node *nd;
+
+ for (nd = rb_first(root); nd; nd = rb_next(nd)) {
+ struct vm_area_struct *vma;
+ vma = rb_entry(nd, struct vm_area_struct, vm_rb);
+ VM_BUG_ON_VMA(vma != ignore &&
+ vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
+ vma);
+ }
+}
+
+static void validate_mm(struct mm_struct *mm)
+{
+ int bug = 0;
+ int i = 0;
+ unsigned long highest_address = 0;
+ struct vm_area_struct *vma = mm->mmap;
+
+ while (vma) {
+ struct anon_vma *anon_vma = vma->anon_vma;
+ struct anon_vma_chain *avc;
+
+ if (anon_vma) {
+ anon_vma_lock_read(anon_vma);
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ anon_vma_interval_tree_verify(avc);
+ anon_vma_unlock_read(anon_vma);
+ }
+
+ highest_address = vm_end_gap(vma);
+ vma = vma->vm_next;
+ i++;
+ }
+ if (i != mm->map_count) {
+ pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
+ bug = 1;
+ }
+ if (highest_address != mm->highest_vm_end) {
+ pr_emerg("mm->highest_vm_end %lx, found %lx\n",
+ mm->highest_vm_end, highest_address);
+ bug = 1;
+ }
+ i = browse_rb(mm);
+ if (i != mm->map_count) {
+ if (i != -1)
+ pr_emerg("map_count %d rb %d\n", mm->map_count, i);
+ bug = 1;
+ }
+ VM_BUG_ON_MM(bug, mm);
+}
+#else
+#define validate_mm_rb(root, ignore) do { } while (0)
+#define validate_mm(mm) do { } while (0)
+#endif
+
+RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
+ unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
+
+/*
+ * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
+ * vma->vm_prev->vm_end values changed, without modifying the vma's position
+ * in the rbtree.
+ */
+static void vma_gap_update(struct vm_area_struct *vma)
+{
+ /*
+ * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
+ * function that does exacltly what we want.
+ */
+ vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
+}
+
+static inline void vma_rb_insert(struct vm_area_struct *vma,
+ struct rb_root *root)
+{
+ /* All rb_subtree_gap values must be consistent prior to insertion */
+ validate_mm_rb(root, NULL);
+
+ rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
+}
+
+static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
+{
+ /*
+ * Note rb_erase_augmented is a fairly large inline function,
+ * so make sure we instantiate it only once with our desired
+ * augmented rbtree callbacks.
+ */
+ rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
+}
+
+static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
+ struct rb_root *root,
+ struct vm_area_struct *ignore)
+{
+ /*
+ * All rb_subtree_gap values must be consistent prior to erase,
+ * with the possible exception of the "next" vma being erased if
+ * next->vm_start was reduced.
+ */
+ validate_mm_rb(root, ignore);
+
+ __vma_rb_erase(vma, root);
+}
+
+static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
+ struct rb_root *root)
+{
+ /*
+ * All rb_subtree_gap values must be consistent prior to erase,
+ * with the possible exception of the vma being erased.
+ */
+ validate_mm_rb(root, vma);
+
+ __vma_rb_erase(vma, root);
+}
+
+/*
+ * vma has some anon_vma assigned, and is already inserted on that
+ * anon_vma's interval trees.
+ *
+ * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
+ * vma must be removed from the anon_vma's interval trees using
+ * anon_vma_interval_tree_pre_update_vma().
+ *
+ * After the update, the vma will be reinserted using
+ * anon_vma_interval_tree_post_update_vma().
+ *
+ * The entire update must be protected by exclusive mmap_sem and by
+ * the root anon_vma's mutex.
+ */
+static inline void
+anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
+{
+ struct anon_vma_chain *avc;
+
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
+}
+
+static inline void
+anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
+{
+ struct anon_vma_chain *avc;
+
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
+}
+
+static int find_vma_links(struct mm_struct *mm, unsigned long addr,
+ unsigned long end, struct vm_area_struct **pprev,
+ struct rb_node ***rb_link, struct rb_node **rb_parent)
+{
+ struct rb_node **__rb_link, *__rb_parent, *rb_prev;
+
+ __rb_link = &mm->mm_rb.rb_node;
+ rb_prev = __rb_parent = NULL;
+
+ while (*__rb_link) {
+ struct vm_area_struct *vma_tmp;
+
+ __rb_parent = *__rb_link;
+ vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
+
+ if (vma_tmp->vm_end > addr) {
+ /* Fail if an existing vma overlaps the area */
+ if (vma_tmp->vm_start < end)
+ return -ENOMEM;
+ __rb_link = &__rb_parent->rb_left;
+ } else {
+ rb_prev = __rb_parent;
+ __rb_link = &__rb_parent->rb_right;
+ }
+ }
+
+ *pprev = NULL;
+ if (rb_prev)
+ *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
+ *rb_link = __rb_link;
+ *rb_parent = __rb_parent;
+ return 0;
+}
+
+static unsigned long count_vma_pages_range(struct mm_struct *mm,
+ unsigned long addr, unsigned long end)
+{
+ unsigned long nr_pages = 0;
+ struct vm_area_struct *vma;
+
+ /* Find first overlaping mapping */
+ vma = find_vma_intersection(mm, addr, end);
+ if (!vma)
+ return 0;
+
+ nr_pages = (min(end, vma->vm_end) -
+ max(addr, vma->vm_start)) >> PAGE_SHIFT;
+
+ /* Iterate over the rest of the overlaps */
+ for (vma = vma->vm_next; vma; vma = vma->vm_next) {
+ unsigned long overlap_len;
+
+ if (vma->vm_start > end)
+ break;
+
+ overlap_len = min(end, vma->vm_end) - vma->vm_start;
+ nr_pages += overlap_len >> PAGE_SHIFT;
+ }
+
+ return nr_pages;
+}
+
+void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
+ struct rb_node **rb_link, struct rb_node *rb_parent)
+{
+ /* Update tracking information for the gap following the new vma. */
+ if (vma->vm_next)
+ vma_gap_update(vma->vm_next);
+ else
+ mm->highest_vm_end = vm_end_gap(vma);
+
+ /*
+ * vma->vm_prev wasn't known when we followed the rbtree to find the
+ * correct insertion point for that vma. As a result, we could not
+ * update the vma vm_rb parents rb_subtree_gap values on the way down.
+ * So, we first insert the vma with a zero rb_subtree_gap value
+ * (to be consistent with what we did on the way down), and then
+ * immediately update the gap to the correct value. Finally we
+ * rebalance the rbtree after all augmented values have been set.
+ */
+ rb_link_node(&vma->vm_rb, rb_parent, rb_link);
+ vma->rb_subtree_gap = 0;
+ vma_gap_update(vma);
+ vma_rb_insert(vma, &mm->mm_rb);
+}
+
+static void __vma_link_file(struct vm_area_struct *vma)
+{
+ struct file *file;
+
+ file = vma->vm_file;
+ if (file) {
+ struct address_space *mapping = file->f_mapping;
+
+ if (vma->vm_flags & VM_DENYWRITE)
+ atomic_dec(&file_inode(file)->i_writecount);
+ if (vma->vm_flags & VM_SHARED)
+ atomic_inc(&mapping->i_mmap_writable);
+
+ flush_dcache_mmap_lock(mapping);
+ vma_interval_tree_insert(vma, &mapping->i_mmap);
+ flush_dcache_mmap_unlock(mapping);
+ }
+}
+
+static void
+__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
+ struct vm_area_struct *prev, struct rb_node **rb_link,
+ struct rb_node *rb_parent)
+{
+ __vma_link_list(mm, vma, prev, rb_parent);
+ __vma_link_rb(mm, vma, rb_link, rb_parent);
+}
+
+static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
+ struct vm_area_struct *prev, struct rb_node **rb_link,
+ struct rb_node *rb_parent)
+{
+ struct address_space *mapping = NULL;
+
+ if (vma->vm_file) {
+ mapping = vma->vm_file->f_mapping;
+ i_mmap_lock_write(mapping);
+ }
+
+ __vma_link(mm, vma, prev, rb_link, rb_parent);
+ __vma_link_file(vma);
+
+ if (mapping)
+ i_mmap_unlock_write(mapping);
+
+ mm->map_count++;
+ validate_mm(mm);
+}
+
+/*
+ * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
+ * mm's list and rbtree. It has already been inserted into the interval tree.
+ */
+static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+ struct vm_area_struct *prev;
+ struct rb_node **rb_link, *rb_parent;
+
+ if (find_vma_links(mm, vma->vm_start, vma->vm_end,
+ &prev, &rb_link, &rb_parent))
+ BUG();
+ __vma_link(mm, vma, prev, rb_link, rb_parent);
+ mm->map_count++;
+}
+
+static __always_inline void __vma_unlink_common(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ struct vm_area_struct *prev,
+ bool has_prev,
+ struct vm_area_struct *ignore)
+{
+ struct vm_area_struct *next;
+
+ vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
+ next = vma->vm_next;
+ if (has_prev)
+ prev->vm_next = next;
+ else {
+ prev = vma->vm_prev;
+ if (prev)
+ prev->vm_next = next;
+ else
+ mm->mmap = next;
+ }
+ if (next)
+ next->vm_prev = prev;
+
+ /* Kill the cache */
+ vmacache_invalidate(mm);
+}
+
+static inline void __vma_unlink_prev(struct mm_struct *mm,
+ struct vm_area_struct *vma,
+ struct vm_area_struct *prev)
+{
+ __vma_unlink_common(mm, vma, prev, true, vma);
+}
+
+/*
+ * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
+ * is already present in an i_mmap tree without adjusting the tree.
+ * The following helper function should be used when such adjustments
+ * are necessary. The "insert" vma (if any) is to be inserted
+ * before we drop the necessary locks.
+ */
+int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
+ struct vm_area_struct *expand)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
+ struct address_space *mapping = NULL;
+ struct rb_root_cached *root = NULL;
+ struct anon_vma *anon_vma = NULL;
+ struct file *file = vma->vm_file;
+ bool start_changed = false, end_changed = false;
+ long adjust_next = 0;
+ int remove_next = 0;
+
+ if (next && !insert) {
+ struct vm_area_struct *exporter = NULL, *importer = NULL;
+
+ if (end >= next->vm_end) {
+ /*
+ * vma expands, overlapping all the next, and
+ * perhaps the one after too (mprotect case 6).
+ * The only other cases that gets here are
+ * case 1, case 7 and case 8.
+ */
+ if (next == expand) {
+ /*
+ * The only case where we don't expand "vma"
+ * and we expand "next" instead is case 8.
+ */
+ VM_WARN_ON(end != next->vm_end);
+ /*
+ * remove_next == 3 means we're
+ * removing "vma" and that to do so we
+ * swapped "vma" and "next".
+ */
+ remove_next = 3;
+ VM_WARN_ON(file != next->vm_file);
+ swap(vma, next);
+ } else {
+ VM_WARN_ON(expand != vma);
+ /*
+ * case 1, 6, 7, remove_next == 2 is case 6,
+ * remove_next == 1 is case 1 or 7.
+ */
+ remove_next = 1 + (end > next->vm_end);
+ VM_WARN_ON(remove_next == 2 &&
+ end != next->vm_next->vm_end);
+ VM_WARN_ON(remove_next == 1 &&
+ end != next->vm_end);
+ /* trim end to next, for case 6 first pass */
+ end = next->vm_end;
+ }
+
+ exporter = next;
+ importer = vma;
+
+ /*
+ * If next doesn't have anon_vma, import from vma after
+ * next, if the vma overlaps with it.
+ */
+ if (remove_next == 2 && !next->anon_vma)
+ exporter = next->vm_next;
+
+ } else if (end > next->vm_start) {
+ /*
+ * vma expands, overlapping part of the next:
+ * mprotect case 5 shifting the boundary up.
+ */
+ adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
+ exporter = next;
+ importer = vma;
+ VM_WARN_ON(expand != importer);
+ } else if (end < vma->vm_end) {
+ /*
+ * vma shrinks, and !insert tells it's not
+ * split_vma inserting another: so it must be
+ * mprotect case 4 shifting the boundary down.
+ */
+ adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
+ exporter = vma;
+ importer = next;
+ VM_WARN_ON(expand != importer);
+ }
+
+ /*
+ * Easily overlooked: when mprotect shifts the boundary,
+ * make sure the expanding vma has anon_vma set if the
+ * shrinking vma had, to cover any anon pages imported.
+ */
+ if (exporter && exporter->anon_vma && !importer->anon_vma) {
+ int error;
+
+ importer->anon_vma = exporter->anon_vma;
+ error = anon_vma_clone(importer, exporter);
+ if (error)
+ return error;
+ }
+ }
+again:
+ vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
+
+ if (file) {
+ mapping = file->f_mapping;
+ root = &mapping->i_mmap;
+ uprobe_munmap(vma, vma->vm_start, vma->vm_end);
+
+ if (adjust_next)
+ uprobe_munmap(next, next->vm_start, next->vm_end);
+
+ i_mmap_lock_write(mapping);
+ if (insert) {
+ /*
+ * Put into interval tree now, so instantiated pages
+ * are visible to arm/parisc __flush_dcache_page
+ * throughout; but we cannot insert into address
+ * space until vma start or end is updated.
+ */
+ __vma_link_file(insert);
+ }
+ }
+
+ anon_vma = vma->anon_vma;
+ if (!anon_vma && adjust_next)
+ anon_vma = next->anon_vma;
+ if (anon_vma) {
+ VM_WARN_ON(adjust_next && next->anon_vma &&
+ anon_vma != next->anon_vma);
+ anon_vma_lock_write(anon_vma);
+ anon_vma_interval_tree_pre_update_vma(vma);
+ if (adjust_next)
+ anon_vma_interval_tree_pre_update_vma(next);
+ }
+
+ if (root) {
+ flush_dcache_mmap_lock(mapping);
+ vma_interval_tree_remove(vma, root);
+ if (adjust_next)
+ vma_interval_tree_remove(next, root);
+ }
+
+ if (start != vma->vm_start) {
+ vma->vm_start = start;
+ start_changed = true;
+ }
+ if (end != vma->vm_end) {
+ vma->vm_end = end;
+ end_changed = true;
+ }
+ vma->vm_pgoff = pgoff;
+ if (adjust_next) {
+ next->vm_start += adjust_next << PAGE_SHIFT;
+ next->vm_pgoff += adjust_next;
+ }
+
+ if (root) {
+ if (adjust_next)
+ vma_interval_tree_insert(next, root);
+ vma_interval_tree_insert(vma, root);
+ flush_dcache_mmap_unlock(mapping);
+ }
+
+ if (remove_next) {
+ /*
+ * vma_merge has merged next into vma, and needs
+ * us to remove next before dropping the locks.
+ */
+ if (remove_next != 3)
+ __vma_unlink_prev(mm, next, vma);
+ else
+ /*
+ * vma is not before next if they've been
+ * swapped.
+ *
+ * pre-swap() next->vm_start was reduced so
+ * tell validate_mm_rb to ignore pre-swap()
+ * "next" (which is stored in post-swap()
+ * "vma").
+ */
+ __vma_unlink_common(mm, next, NULL, false, vma);
+ if (file)
+ __remove_shared_vm_struct(next, file, mapping);
+ } else if (insert) {
+ /*
+ * split_vma has split insert from vma, and needs
+ * us to insert it before dropping the locks
+ * (it may either follow vma or precede it).
+ */
+ __insert_vm_struct(mm, insert);
+ } else {
+ if (start_changed)
+ vma_gap_update(vma);
+ if (end_changed) {
+ if (!next)
+ mm->highest_vm_end = vm_end_gap(vma);
+ else if (!adjust_next)
+ vma_gap_update(next);
+ }
+ }
+
+ if (anon_vma) {
+ anon_vma_interval_tree_post_update_vma(vma);
+ if (adjust_next)
+ anon_vma_interval_tree_post_update_vma(next);
+ anon_vma_unlock_write(anon_vma);
+ }
+ if (mapping)
+ i_mmap_unlock_write(mapping);
+
+ if (root) {
+ uprobe_mmap(vma);
+
+ if (adjust_next)
+ uprobe_mmap(next);
+ }
+
+ if (remove_next) {
+ if (file) {
+ uprobe_munmap(next, next->vm_start, next->vm_end);
+ fput(file);
+ }
+ if (next->anon_vma)
+ anon_vma_merge(vma, next);
+ mm->map_count--;
+ mpol_put(vma_policy(next));
+ vm_area_free(next);
+ /*
+ * In mprotect's case 6 (see comments on vma_merge),
+ * we must remove another next too. It would clutter
+ * up the code too much to do both in one go.
+ */
+ if (remove_next != 3) {
+ /*
+ * If "next" was removed and vma->vm_end was
+ * expanded (up) over it, in turn
+ * "next->vm_prev->vm_end" changed and the
+ * "vma->vm_next" gap must be updated.
+ */
+ next = vma->vm_next;
+ } else {
+ /*
+ * For the scope of the comment "next" and
+ * "vma" considered pre-swap(): if "vma" was
+ * removed, next->vm_start was expanded (down)
+ * over it and the "next" gap must be updated.
+ * Because of the swap() the post-swap() "vma"
+ * actually points to pre-swap() "next"
+ * (post-swap() "next" as opposed is now a
+ * dangling pointer).
+ */
+ next = vma;
+ }
+ if (remove_next == 2) {
+ remove_next = 1;
+ end = next->vm_end;
+ goto again;
+ }
+ else if (next)
+ vma_gap_update(next);
+ else {
+ /*
+ * If remove_next == 2 we obviously can't
+ * reach this path.
+ *
+ * If remove_next == 3 we can't reach this
+ * path because pre-swap() next is always not
+ * NULL. pre-swap() "next" is not being
+ * removed and its next->vm_end is not altered
+ * (and furthermore "end" already matches
+ * next->vm_end in remove_next == 3).
+ *
+ * We reach this only in the remove_next == 1
+ * case if the "next" vma that was removed was
+ * the highest vma of the mm. However in such
+ * case next->vm_end == "end" and the extended
+ * "vma" has vma->vm_end == next->vm_end so
+ * mm->highest_vm_end doesn't need any update
+ * in remove_next == 1 case.
+ */
+ VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
+ }
+ }
+ if (insert && file)
+ uprobe_mmap(insert);
+
+ validate_mm(mm);
+
+ return 0;
+}
+
+/*
+ * If the vma has a ->close operation then the driver probably needs to release
+ * per-vma resources, so we don't attempt to merge those.
+ */
+static inline int is_mergeable_vma(struct vm_area_struct *vma,
+ struct file *file, unsigned long vm_flags,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+ /*
+ * VM_SOFTDIRTY should not prevent from VMA merging, if we
+ * match the flags but dirty bit -- the caller should mark
+ * merged VMA as dirty. If dirty bit won't be excluded from
+ * comparison, we increase pressue on the memory system forcing
+ * the kernel to generate new VMAs when old one could be
+ * extended instead.
+ */
+ if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
+ return 0;
+ if (vma->vm_file != file)
+ return 0;
+ if (vma->vm_ops && vma->vm_ops->close)
+ return 0;
+ if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
+ return 0;
+ return 1;
+}
+
+static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
+ struct anon_vma *anon_vma2,
+ struct vm_area_struct *vma)
+{
+ /*
+ * The list_is_singular() test is to avoid merging VMA cloned from
+ * parents. This can improve scalability caused by anon_vma lock.
+ */
+ if ((!anon_vma1 || !anon_vma2) && (!vma ||
+ list_is_singular(&vma->anon_vma_chain)))
+ return 1;
+ return anon_vma1 == anon_vma2;
+}
+
+/*
+ * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
+ * in front of (at a lower virtual address and file offset than) the vma.
+ *
+ * We cannot merge two vmas if they have differently assigned (non-NULL)
+ * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
+ *
+ * We don't check here for the merged mmap wrapping around the end of pagecache
+ * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
+ * wrap, nor mmaps which cover the final page at index -1UL.
+ */
+static int
+can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t vm_pgoff,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
+ is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
+ if (vma->vm_pgoff == vm_pgoff)
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
+ * beyond (at a higher virtual address and file offset than) the vma.
+ *
+ * We cannot merge two vmas if they have differently assigned (non-NULL)
+ * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
+ */
+static int
+can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t vm_pgoff,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
+ is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
+ pgoff_t vm_pglen;
+ vm_pglen = vma_pages(vma);
+ if (vma->vm_pgoff + vm_pglen == vm_pgoff)
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
+ * whether that can be merged with its predecessor or its successor.
+ * Or both (it neatly fills a hole).
+ *
+ * In most cases - when called for mmap, brk or mremap - [addr,end) is
+ * certain not to be mapped by the time vma_merge is called; but when
+ * called for mprotect, it is certain to be already mapped (either at
+ * an offset within prev, or at the start of next), and the flags of
+ * this area are about to be changed to vm_flags - and the no-change
+ * case has already been eliminated.
+ *
+ * The following mprotect cases have to be considered, where AAAA is
+ * the area passed down from mprotect_fixup, never extending beyond one
+ * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
+ *
+ * AAAA AAAA AAAA AAAA
+ * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
+ * cannot merge might become might become might become
+ * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
+ * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
+ * mremap move: PPPPXXXXXXXX 8
+ * AAAA
+ * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
+ * might become case 1 below case 2 below case 3 below
+ *
+ * It is important for case 8 that the the vma NNNN overlapping the
+ * region AAAA is never going to extended over XXXX. Instead XXXX must
+ * be extended in region AAAA and NNNN must be removed. This way in
+ * all cases where vma_merge succeeds, the moment vma_adjust drops the
+ * rmap_locks, the properties of the merged vma will be already
+ * correct for the whole merged range. Some of those properties like
+ * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
+ * be correct for the whole merged range immediately after the
+ * rmap_locks are released. Otherwise if XXXX would be removed and
+ * NNNN would be extended over the XXXX range, remove_migration_ptes
+ * or other rmap walkers (if working on addresses beyond the "end"
+ * parameter) may establish ptes with the wrong permissions of NNNN
+ * instead of the right permissions of XXXX.
+ */
+struct vm_area_struct *vma_merge(struct mm_struct *mm,
+ struct vm_area_struct *prev, unsigned long addr,
+ unsigned long end, unsigned long vm_flags,
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t pgoff, struct mempolicy *policy,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
+{
+ pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
+ struct vm_area_struct *area, *next;
+ int err;
+
+ /*
+ * We later require that vma->vm_flags == vm_flags,
+ * so this tests vma->vm_flags & VM_SPECIAL, too.
+ */
+ if (vm_flags & VM_SPECIAL)
+ return NULL;
+
+ if (prev)
+ next = prev->vm_next;
+ else
+ next = mm->mmap;
+ area = next;
+ if (area && area->vm_end == end) /* cases 6, 7, 8 */
+ next = next->vm_next;
+
+ /* verify some invariant that must be enforced by the caller */
+ VM_WARN_ON(prev && addr <= prev->vm_start);
+ VM_WARN_ON(area && end > area->vm_end);
+ VM_WARN_ON(addr >= end);
+
+ /*
+ * Can it merge with the predecessor?
+ */
+ if (prev && prev->vm_end == addr &&
+ mpol_equal(vma_policy(prev), policy) &&
+ can_vma_merge_after(prev, vm_flags,
+ anon_vma, file, pgoff,
+ vm_userfaultfd_ctx)) {
+ /*
+ * OK, it can. Can we now merge in the successor as well?
+ */
+ if (next && end == next->vm_start &&
+ mpol_equal(policy, vma_policy(next)) &&
+ can_vma_merge_before(next, vm_flags,
+ anon_vma, file,
+ pgoff+pglen,
+ vm_userfaultfd_ctx) &&
+ is_mergeable_anon_vma(prev->anon_vma,
+ next->anon_vma, NULL)) {
+ /* cases 1, 6 */
+ err = __vma_adjust(prev, prev->vm_start,
+ next->vm_end, prev->vm_pgoff, NULL,
+ prev);
+ } else /* cases 2, 5, 7 */
+ err = __vma_adjust(prev, prev->vm_start,
+ end, prev->vm_pgoff, NULL, prev);
+ if (err)
+ return NULL;
+ khugepaged_enter_vma_merge(prev, vm_flags);
+ return prev;
+ }
+
+ /*
+ * Can this new request be merged in front of next?
+ */
+ if (next && end == next->vm_start &&
+ mpol_equal(policy, vma_policy(next)) &&
+ can_vma_merge_before(next, vm_flags,
+ anon_vma, file, pgoff+pglen,
+ vm_userfaultfd_ctx)) {
+ if (prev && addr < prev->vm_end) /* case 4 */
+ err = __vma_adjust(prev, prev->vm_start,
+ addr, prev->vm_pgoff, NULL, next);
+ else { /* cases 3, 8 */
+ err = __vma_adjust(area, addr, next->vm_end,
+ next->vm_pgoff - pglen, NULL, next);
+ /*
+ * In case 3 area is already equal to next and
+ * this is a noop, but in case 8 "area" has
+ * been removed and next was expanded over it.
+ */
+ area = next;
+ }
+ if (err)
+ return NULL;
+ khugepaged_enter_vma_merge(area, vm_flags);
+ return area;
+ }
+
+ return NULL;
+}
+
+/*
+ * Rough compatbility check to quickly see if it's even worth looking
+ * at sharing an anon_vma.
+ *
+ * They need to have the same vm_file, and the flags can only differ
+ * in things that mprotect may change.
+ *
+ * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
+ * we can merge the two vma's. For example, we refuse to merge a vma if
+ * there is a vm_ops->close() function, because that indicates that the
+ * driver is doing some kind of reference counting. But that doesn't
+ * really matter for the anon_vma sharing case.
+ */
+static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
+{
+ return a->vm_end == b->vm_start &&
+ mpol_equal(vma_policy(a), vma_policy(b)) &&
+ a->vm_file == b->vm_file &&
+ !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
+ b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
+}
+
+/*
+ * Do some basic sanity checking to see if we can re-use the anon_vma
+ * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
+ * the same as 'old', the other will be the new one that is trying
+ * to share the anon_vma.
+ *
+ * NOTE! This runs with mm_sem held for reading, so it is possible that
+ * the anon_vma of 'old' is concurrently in the process of being set up
+ * by another page fault trying to merge _that_. But that's ok: if it
+ * is being set up, that automatically means that it will be a singleton
+ * acceptable for merging, so we can do all of this optimistically. But
+ * we do that READ_ONCE() to make sure that we never re-load the pointer.
+ *
+ * IOW: that the "list_is_singular()" test on the anon_vma_chain only
+ * matters for the 'stable anon_vma' case (ie the thing we want to avoid
+ * is to return an anon_vma that is "complex" due to having gone through
+ * a fork).
+ *
+ * We also make sure that the two vma's are compatible (adjacent,
+ * and with the same memory policies). That's all stable, even with just
+ * a read lock on the mm_sem.
+ */
+static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
+{
+ if (anon_vma_compatible(a, b)) {
+ struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
+
+ if (anon_vma && list_is_singular(&old->anon_vma_chain))
+ return anon_vma;
+ }
+ return NULL;
+}
+
+/*
+ * find_mergeable_anon_vma is used by anon_vma_prepare, to check
+ * neighbouring vmas for a suitable anon_vma, before it goes off
+ * to allocate a new anon_vma. It checks because a repetitive
+ * sequence of mprotects and faults may otherwise lead to distinct
+ * anon_vmas being allocated, preventing vma merge in subsequent
+ * mprotect.
+ */
+struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
+{
+ struct anon_vma *anon_vma;
+ struct vm_area_struct *near;
+
+ near = vma->vm_next;
+ if (!near)
+ goto try_prev;
+
+ anon_vma = reusable_anon_vma(near, vma, near);
+ if (anon_vma)
+ return anon_vma;
+try_prev:
+ near = vma->vm_prev;
+ if (!near)
+ goto none;
+
+ anon_vma = reusable_anon_vma(near, near, vma);
+ if (anon_vma)
+ return anon_vma;
+none:
+ /*
+ * There's no absolute need to look only at touching neighbours:
+ * we could search further afield for "compatible" anon_vmas.
+ * But it would probably just be a waste of time searching,
+ * or lead to too many vmas hanging off the same anon_vma.
+ * We're trying to allow mprotect remerging later on,
+ * not trying to minimize memory used for anon_vmas.
+ */
+ return NULL;
+}
+
+/*
+ * If a hint addr is less than mmap_min_addr change hint to be as
+ * low as possible but still greater than mmap_min_addr
+ */
+static inline unsigned long round_hint_to_min(unsigned long hint)
+{
+ hint &= PAGE_MASK;
+ if (((void *)hint != NULL) &&
+ (hint < mmap_min_addr))
+ return PAGE_ALIGN(mmap_min_addr);
+ return hint;
+}
+
+static inline int mlock_future_check(struct mm_struct *mm,
+ unsigned long flags,
+ unsigned long len)
+{
+ unsigned long locked, lock_limit;
+
+ /* mlock MCL_FUTURE? */
+ if (flags & VM_LOCKED) {
+ locked = len >> PAGE_SHIFT;
+ locked += mm->locked_vm;
+ lock_limit = rlimit(RLIMIT_MEMLOCK);
+ lock_limit >>= PAGE_SHIFT;
+ if (locked > lock_limit && !capable(CAP_IPC_LOCK))
+ return -EAGAIN;
+ }
+ return 0;
+}
+
+static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
+{
+ if (S_ISREG(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ if (S_ISBLK(inode->i_mode))
+ return MAX_LFS_FILESIZE;
+
+ /* Special "we do even unsigned file positions" case */
+ if (file->f_mode & FMODE_UNSIGNED_OFFSET)
+ return 0;
+
+ /* Yes, random drivers might want more. But I'm tired of buggy drivers */
+ return ULONG_MAX;
+}
+
+static inline bool file_mmap_ok(struct file *file, struct inode *inode,
+ unsigned long pgoff, unsigned long len)
+{
+ u64 maxsize = file_mmap_size_max(file, inode);
+
+ if (maxsize && len > maxsize)
+ return false;
+ maxsize -= len;
+ if (pgoff > maxsize >> PAGE_SHIFT)
+ return false;
+ return true;
+}
+
+/*
+ * The caller must hold down_write(¤t->mm->mmap_sem).
+ */
+unsigned long do_mmap(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long prot,
+ unsigned long flags, vm_flags_t vm_flags,
+ unsigned long pgoff, unsigned long *populate,
+ struct list_head *uf)
+{
+ struct mm_struct *mm = current->mm;
+ int pkey = 0;
+
+ *populate = 0;
+
+ if (!len)
+ return -EINVAL;
+
+ /*
+ * Does the application expect PROT_READ to imply PROT_EXEC?
+ *
+ * (the exception is when the underlying filesystem is noexec
+ * mounted, in which case we dont add PROT_EXEC.)
+ */
+ if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
+ if (!(file && path_noexec(&file->f_path)))
+ prot |= PROT_EXEC;
+
+ /* force arch specific MAP_FIXED handling in get_unmapped_area */
+ if (flags & MAP_FIXED_NOREPLACE)
+ flags |= MAP_FIXED;
+
+ if (!(flags & MAP_FIXED))
+ addr = round_hint_to_min(addr);
+
+ /* Careful about overflows.. */
+ len = PAGE_ALIGN(len);
+ if (!len)
+ return -ENOMEM;
+
+ /* offset overflow? */
+ if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
+ return -EOVERFLOW;
+
+ /* Too many mappings? */
+ if (mm->map_count > sysctl_max_map_count)
+ return -ENOMEM;
+
+ /* Obtain the address to map to. we verify (or select) it and ensure
+ * that it represents a valid section of the address space.
+ */
+ addr = get_unmapped_area(file, addr, len, pgoff, flags);
+ if (offset_in_page(addr))
+ return addr;
+
+ if (flags & MAP_FIXED_NOREPLACE) {
+ struct vm_area_struct *vma = find_vma(mm, addr);
+
+ if (vma && vma->vm_start < addr + len)
+ return -EEXIST;
+ }
+
+ if (prot == PROT_EXEC) {
+ pkey = execute_only_pkey(mm);
+ if (pkey < 0)
+ pkey = 0;
+ }
+
+ /* Do simple checking here so the lower-level routines won't have
+ * to. we assume access permissions have been handled by the open
+ * of the memory object, so we don't do any here.
+ */
+ vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
+ mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+
+ if (flags & MAP_LOCKED)
+ if (!can_do_mlock())
+ return -EPERM;
+
+ if (mlock_future_check(mm, vm_flags, len))
+ return -EAGAIN;
+
+ if (file) {
+ struct inode *inode = file_inode(file);
+ unsigned long flags_mask;
+
+ if (!file_mmap_ok(file, inode, pgoff, len))
+ return -EOVERFLOW;
+
+ flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
+
+ switch (flags & MAP_TYPE) {
+ case MAP_SHARED:
+ /*
+ * Force use of MAP_SHARED_VALIDATE with non-legacy
+ * flags. E.g. MAP_SYNC is dangerous to use with
+ * MAP_SHARED as you don't know which consistency model
+ * you will get. We silently ignore unsupported flags
+ * with MAP_SHARED to preserve backward compatibility.
+ */
+ flags &= LEGACY_MAP_MASK;
+ /* fall through */
+ case MAP_SHARED_VALIDATE:
+ if (flags & ~flags_mask)
+ return -EOPNOTSUPP;
+ if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
+ return -EACCES;
+
+ /*
+ * Make sure we don't allow writing to an append-only
+ * file..
+ */
+ if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
+ return -EACCES;
+
+ /*
+ * Make sure there are no mandatory locks on the file.
+ */
+ if (locks_verify_locked(file))
+ return -EAGAIN;
+
+ vm_flags |= VM_SHARED | VM_MAYSHARE;
+ if (!(file->f_mode & FMODE_WRITE))
+ vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
+
+ /* fall through */
+ case MAP_PRIVATE:
+ if (!(file->f_mode & FMODE_READ))
+ return -EACCES;
+ if (path_noexec(&file->f_path)) {
+ if (vm_flags & VM_EXEC)
+ return -EPERM;
+ vm_flags &= ~VM_MAYEXEC;
+ }
+
+ if (!file->f_op->mmap)
+ return -ENODEV;
+ if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
+ return -EINVAL;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+ } else {
+ switch (flags & MAP_TYPE) {
+ case MAP_SHARED:
+ if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
+ return -EINVAL;
+ /*
+ * Ignore pgoff.
+ */
+ pgoff = 0;
+ vm_flags |= VM_SHARED | VM_MAYSHARE;
+ break;
+ case MAP_PRIVATE:
+ /*
+ * Set pgoff according to addr for anon_vma.
+ */
+ pgoff = addr >> PAGE_SHIFT;
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+
+ /*
+ * Set 'VM_NORESERVE' if we should not account for the
+ * memory use of this mapping.
+ */
+ if (flags & MAP_NORESERVE) {
+ /* We honor MAP_NORESERVE if allowed to overcommit */
+ if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
+ vm_flags |= VM_NORESERVE;
+
+ /* hugetlb applies strict overcommit unless MAP_NORESERVE */
+ if (file && is_file_hugepages(file))
+ vm_flags |= VM_NORESERVE;
+ }
+
+ addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
+ if (!IS_ERR_VALUE(addr) &&
+ ((vm_flags & VM_LOCKED) ||
+ (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
+ *populate = len;
+ return addr;
+}
+
+unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
+ unsigned long prot, unsigned long flags,
+ unsigned long fd, unsigned long pgoff)
+{
+ struct file *file = NULL;
+ unsigned long retval;
+
+ if (!(flags & MAP_ANONYMOUS)) {
+ audit_mmap_fd(fd, flags);
+ file = fget(fd);
+ if (!file)
+ return -EBADF;
+ if (is_file_hugepages(file))
+ len = ALIGN(len, huge_page_size(hstate_file(file)));
+ retval = -EINVAL;
+ if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
+ goto out_fput;
+ } else if (flags & MAP_HUGETLB) {
+ struct user_struct *user = NULL;
+ struct hstate *hs;
+
+ hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
+ if (!hs)
+ return -EINVAL;
+
+ len = ALIGN(len, huge_page_size(hs));
+ /*
+ * VM_NORESERVE is used because the reservations will be
+ * taken when vm_ops->mmap() is called
+ * A dummy user value is used because we are not locking
+ * memory so no accounting is necessary
+ */
+ file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
+ VM_NORESERVE,
+ &user, HUGETLB_ANONHUGE_INODE,
+ (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+ }
+
+ flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
+
+ retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
+out_fput:
+ if (file)
+ fput(file);
+ return retval;
+}
+
+SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
+ unsigned long, prot, unsigned long, flags,
+ unsigned long, fd, unsigned long, pgoff)
+{
+ return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
+}
+
+#ifdef __ARCH_WANT_SYS_OLD_MMAP
+struct mmap_arg_struct {
+ unsigned long addr;
+ unsigned long len;
+ unsigned long prot;
+ unsigned long flags;
+ unsigned long fd;
+ unsigned long offset;
+};
+
+SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
+{
+ struct mmap_arg_struct a;
+
+ if (copy_from_user(&a, arg, sizeof(a)))
+ return -EFAULT;
+ if (offset_in_page(a.offset))
+ return -EINVAL;
+
+ return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
+ a.offset >> PAGE_SHIFT);
+}
+#endif /* __ARCH_WANT_SYS_OLD_MMAP */
+
+/*
+ * Some shared mappigns will want the pages marked read-only
+ * to track write events. If so, we'll downgrade vm_page_prot
+ * to the private version (using protection_map[] without the
+ * VM_SHARED bit).
+ */
+int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
+{
+ vm_flags_t vm_flags = vma->vm_flags;
+ const struct vm_operations_struct *vm_ops = vma->vm_ops;
+
+ /* If it was private or non-writable, the write bit is already clear */
+ if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
+ return 0;
+
+ /* The backer wishes to know when pages are first written to? */
+ if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
+ return 1;
+
+ /* The open routine did something to the protections that pgprot_modify
+ * won't preserve? */
+ if (pgprot_val(vm_page_prot) !=
+ pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
+ return 0;
+
+ /* Do we need to track softdirty? */
+ if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
+ return 1;
+
+ /* Specialty mapping? */
+ if (vm_flags & VM_PFNMAP)
+ return 0;
+
+ /* Can the mapping track the dirty pages? */
+ return vma->vm_file && vma->vm_file->f_mapping &&
+ mapping_cap_account_dirty(vma->vm_file->f_mapping);
+}
+
+/*
+ * We account for memory if it's a private writeable mapping,
+ * not hugepages and VM_NORESERVE wasn't set.
+ */
+static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
+{
+ /*
+ * hugetlb has its own accounting separate from the core VM
+ * VM_HUGETLB may not be set yet so we cannot check for that flag.
+ */
+ if (file && is_file_hugepages(file))
+ return 0;
+
+ return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
+}
+
+unsigned long mmap_region(struct file *file, unsigned long addr,
+ unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
+ struct list_head *uf)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma, *prev;
+ int error;
+ struct rb_node **rb_link, *rb_parent;
+ unsigned long charged = 0;
+
+ /* Check against address space limit. */
+ if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
+ unsigned long nr_pages;
+
+ /*
+ * MAP_FIXED may remove pages of mappings that intersects with
+ * requested mapping. Account for the pages it would unmap.
+ */
+ nr_pages = count_vma_pages_range(mm, addr, addr + len);
+
+ if (!may_expand_vm(mm, vm_flags,
+ (len >> PAGE_SHIFT) - nr_pages))
+ return -ENOMEM;
+ }
+
+ /* Clear old maps */
+ while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
+ &rb_parent)) {
+ if (do_munmap(mm, addr, len, uf))
+ return -ENOMEM;
+ }
+
+ /*
+ * Private writable mapping: check memory availability
+ */
+ if (accountable_mapping(file, vm_flags)) {
+ charged = len >> PAGE_SHIFT;
+ if (security_vm_enough_memory_mm(mm, charged))
+ return -ENOMEM;
+ vm_flags |= VM_ACCOUNT;
+ }
+
+ /*
+ * Can we just expand an old mapping?
+ */
+ vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
+ NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
+ if (vma)
+ goto out;
+
+ /*
+ * Determine the object being mapped and call the appropriate
+ * specific mapper. the address has already been validated, but
+ * not unmapped, but the maps are removed from the list.
+ */
+ vma = vm_area_alloc(mm);
+ if (!vma) {
+ error = -ENOMEM;
+ goto unacct_error;
+ }
+
+ vma->vm_start = addr;
+ vma->vm_end = addr + len;
+ vma->vm_flags = vm_flags;
+ vma->vm_page_prot = vm_get_page_prot(vm_flags);
+ vma->vm_pgoff = pgoff;
+
+ if (file) {
+ if (vm_flags & VM_DENYWRITE) {
+ error = deny_write_access(file);
+ if (error)
+ goto free_vma;
+ }
+ if (vm_flags & VM_SHARED) {
+ error = mapping_map_writable(file->f_mapping);
+ if (error)
+ goto allow_write_and_free_vma;
+ }
+
+ /* ->mmap() can change vma->vm_file, but must guarantee that
+ * vma_link() below can deny write-access if VM_DENYWRITE is set
+ * and map writably if VM_SHARED is set. This usually means the
+ * new file must not have been exposed to user-space, yet.
+ */
+ vma->vm_file = get_file(file);
+ error = call_mmap(file, vma);
+ if (error)
+ goto unmap_and_free_vma;
+
+ /* Can addr have changed??
+ *
+ * Answer: Yes, several device drivers can do it in their
+ * f_op->mmap method. -DaveM
+ * Bug: If addr is changed, prev, rb_link, rb_parent should
+ * be updated for vma_link()
+ */
+ WARN_ON_ONCE(addr != vma->vm_start);
+
+ addr = vma->vm_start;
+ vm_flags = vma->vm_flags;
+ } else if (vm_flags & VM_SHARED) {
+ error = shmem_zero_setup(vma);
+ if (error)
+ goto free_vma;
+ } else {
+ vma_set_anonymous(vma);
+ }
+
+ vma_link(mm, vma, prev, rb_link, rb_parent);
+ /* Once vma denies write, undo our temporary denial count */
+ if (file) {
+ if (vm_flags & VM_SHARED)
+ mapping_unmap_writable(file->f_mapping);
+ if (vm_flags & VM_DENYWRITE)
+ allow_write_access(file);
+ }
+ file = vma->vm_file;
+out:
+ perf_event_mmap(vma);
+
+ vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
+ if (vm_flags & VM_LOCKED) {
+ if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
+ is_vm_hugetlb_page(vma) ||
+ vma == get_gate_vma(current->mm))
+ vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
+ else
+ mm->locked_vm += (len >> PAGE_SHIFT);
+ }
+
+ if (file)
+ uprobe_mmap(vma);
+
+ /*
+ * New (or expanded) vma always get soft dirty status.
+ * Otherwise user-space soft-dirty page tracker won't
+ * be able to distinguish situation when vma area unmapped,
+ * then new mapped in-place (which must be aimed as
+ * a completely new data area).
+ */
+ vma->vm_flags |= VM_SOFTDIRTY;
+
+ vma_set_page_prot(vma);
+
+ return addr;
+
+unmap_and_free_vma:
+ vma->vm_file = NULL;
+ fput(file);
+
+ /* Undo any partial mapping done by a device driver. */
+ unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
+ charged = 0;
+ if (vm_flags & VM_SHARED)
+ mapping_unmap_writable(file->f_mapping);
+allow_write_and_free_vma:
+ if (vm_flags & VM_DENYWRITE)
+ allow_write_access(file);
+free_vma:
+ vm_area_free(vma);
+unacct_error:
+ if (charged)
+ vm_unacct_memory(charged);
+ return error;
+}
+
+unsigned long unmapped_area(struct vm_unmapped_area_info *info)
+{
+ /*
+ * We implement the search by looking for an rbtree node that
+ * immediately follows a suitable gap. That is,
+ * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
+ * - gap_end = vma->vm_start >= info->low_limit + length;
+ * - gap_end - gap_start >= length
+ */
+
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long length, low_limit, high_limit, gap_start, gap_end;
+
+ /* Adjust search length to account for worst case alignment overhead */
+ length = info->length + info->align_mask;
+ if (length < info->length)
+ return -ENOMEM;
+
+ /* Adjust search limits by the desired length */
+ if (info->high_limit < length)
+ return -ENOMEM;
+ high_limit = info->high_limit - length;
+
+ if (info->low_limit > high_limit)
+ return -ENOMEM;
+ low_limit = info->low_limit + length;
+
+ /* Check if rbtree root looks promising */
+ if (RB_EMPTY_ROOT(&mm->mm_rb))
+ goto check_highest;
+ vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
+ if (vma->rb_subtree_gap < length)
+ goto check_highest;
+
+ while (true) {
+ /* Visit left subtree if it looks promising */
+ gap_end = vm_start_gap(vma);
+ if (gap_end >= low_limit && vma->vm_rb.rb_left) {
+ struct vm_area_struct *left =
+ rb_entry(vma->vm_rb.rb_left,
+ struct vm_area_struct, vm_rb);
+ if (left->rb_subtree_gap >= length) {
+ vma = left;
+ continue;
+ }
+ }
+
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+check_current:
+ /* Check if current node has a suitable gap */
+ if (gap_start > high_limit)
+ return -ENOMEM;
+ if (gap_end >= low_limit &&
+ gap_end > gap_start && gap_end - gap_start >= length)
+ goto found;
+
+ /* Visit right subtree if it looks promising */
+ if (vma->vm_rb.rb_right) {
+ struct vm_area_struct *right =
+ rb_entry(vma->vm_rb.rb_right,
+ struct vm_area_struct, vm_rb);
+ if (right->rb_subtree_gap >= length) {
+ vma = right;
+ continue;
+ }
+ }
+
+ /* Go back up the rbtree to find next candidate node */
+ while (true) {
+ struct rb_node *prev = &vma->vm_rb;
+ if (!rb_parent(prev))
+ goto check_highest;
+ vma = rb_entry(rb_parent(prev),
+ struct vm_area_struct, vm_rb);
+ if (prev == vma->vm_rb.rb_left) {
+ gap_start = vm_end_gap(vma->vm_prev);
+ gap_end = vm_start_gap(vma);
+ goto check_current;
+ }
+ }
+ }
+
+check_highest:
+ /* Check highest gap, which does not precede any rbtree node */
+ gap_start = mm->highest_vm_end;
+ gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
+ if (gap_start > high_limit)
+ return -ENOMEM;
+
+found:
+ /* We found a suitable gap. Clip it with the original low_limit. */
+ if (gap_start < info->low_limit)
+ gap_start = info->low_limit;
+
+ /* Adjust gap address to the desired alignment */
+ gap_start += (info->align_offset - gap_start) & info->align_mask;
+
+ VM_BUG_ON(gap_start + info->length > info->high_limit);
+ VM_BUG_ON(gap_start + info->length > gap_end);
+ return gap_start;
+}
+
+unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long length, low_limit, high_limit, gap_start, gap_end;
+
+ /* Adjust search length to account for worst case alignment overhead */
+ length = info->length + info->align_mask;
+ if (length < info->length)
+ return -ENOMEM;
+
+ /*
+ * Adjust search limits by the desired length.
+ * See implementation comment at top of unmapped_area().
+ */
+ gap_end = info->high_limit;
+ if (gap_end < length)
+ return -ENOMEM;
+ high_limit = gap_end - length;
+
+ if (info->low_limit > high_limit)
+ return -ENOMEM;
+ low_limit = info->low_limit + length;
+
+ /* Check highest gap, which does not precede any rbtree node */
+ gap_start = mm->highest_vm_end;
+ if (gap_start <= high_limit)
+ goto found_highest;
+
+ /* Check if rbtree root looks promising */
+ if (RB_EMPTY_ROOT(&mm->mm_rb))
+ return -ENOMEM;
+ vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
+ if (vma->rb_subtree_gap < length)
+ return -ENOMEM;
+
+ while (true) {
+ /* Visit right subtree if it looks promising */
+ gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
+ if (gap_start <= high_limit && vma->vm_rb.rb_right) {
+ struct vm_area_struct *right =
+ rb_entry(vma->vm_rb.rb_right,
+ struct vm_area_struct, vm_rb);
+ if (right->rb_subtree_gap >= length) {
+ vma = right;
+ continue;
+ }
+ }
+
+check_current:
+ /* Check if current node has a suitable gap */
+ gap_end = vm_start_gap(vma);
+ if (gap_end < low_limit)
+ return -ENOMEM;
+ if (gap_start <= high_limit &&
+ gap_end > gap_start && gap_end - gap_start >= length)
+ goto found;
+
+ /* Visit left subtree if it looks promising */
+ if (vma->vm_rb.rb_left) {
+ struct vm_area_struct *left =
+ rb_entry(vma->vm_rb.rb_left,
+ struct vm_area_struct, vm_rb);
+ if (left->rb_subtree_gap >= length) {
+ vma = left;
+ continue;
+ }
+ }
+
+ /* Go back up the rbtree to find next candidate node */
+ while (true) {
+ struct rb_node *prev = &vma->vm_rb;
+ if (!rb_parent(prev))
+ return -ENOMEM;
+ vma = rb_entry(rb_parent(prev),
+ struct vm_area_struct, vm_rb);
+ if (prev == vma->vm_rb.rb_right) {
+ gap_start = vma->vm_prev ?
+ vm_end_gap(vma->vm_prev) : 0;
+ goto check_current;
+ }
+ }
+ }
+
+found:
+ /* We found a suitable gap. Clip it with the original high_limit. */
+ if (gap_end > info->high_limit)
+ gap_end = info->high_limit;
+
+found_highest:
+ /* Compute highest gap address at the desired alignment */
+ gap_end -= info->length;
+ gap_end -= (gap_end - info->align_offset) & info->align_mask;
+
+ VM_BUG_ON(gap_end < info->low_limit);
+ VM_BUG_ON(gap_end < gap_start);
+ return gap_end;
+}
+
+/* Get an address range which is currently unmapped.
+ * For shmat() with addr=0.
+ *
+ * Ugly calling convention alert:
+ * Return value with the low bits set means error value,
+ * ie
+ * if (ret & ~PAGE_MASK)
+ * error = ret;
+ *
+ * This function "knows" that -ENOMEM has the bits set.
+ */
+#ifndef HAVE_ARCH_UNMAPPED_AREA
+unsigned long
+arch_get_unmapped_area(struct file *filp, unsigned long addr,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma, *prev;
+ struct vm_unmapped_area_info info;
+
+ if (len > TASK_SIZE - mmap_min_addr)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED)
+ return addr;
+
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma_prev(mm, addr, &prev);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
+ return addr;
+ }
+
+ info.flags = 0;
+ info.length = len;
+ info.low_limit = mm->mmap_base;
+ info.high_limit = TASK_SIZE;
+ info.align_mask = 0;
+ return vm_unmapped_area(&info);
+}
+#endif
+
+/*
+ * This mmap-allocator allocates new areas top-down from below the
+ * stack's low limit (the base):
+ */
+#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+ const unsigned long len, const unsigned long pgoff,
+ const unsigned long flags)
+{
+ struct vm_area_struct *vma, *prev;
+ struct mm_struct *mm = current->mm;
+ unsigned long addr = addr0;
+ struct vm_unmapped_area_info info;
+
+ /* requested length too big for entire address space */
+ if (len > TASK_SIZE - mmap_min_addr)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED)
+ return addr;
+
+ /* requesting a specific address */
+ if (addr) {
+ addr = PAGE_ALIGN(addr);
+ vma = find_vma_prev(mm, addr, &prev);
+ if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+ (!vma || addr + len <= vm_start_gap(vma)) &&
+ (!prev || addr >= vm_end_gap(prev)))
+ return addr;
+ }
+
+ info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+ info.length = len;
+ info.low_limit = max(PAGE_SIZE, mmap_min_addr);
+ info.high_limit = mm->mmap_base;
+ info.align_mask = 0;
+ addr = vm_unmapped_area(&info);
+
+ /*
+ * A failed mmap() very likely causes application failure,
+ * so fall back to the bottom-up function here. This scenario
+ * can happen with large stack limits and large mmap()
+ * allocations.
+ */
+ if (offset_in_page(addr)) {
+ VM_BUG_ON(addr != -ENOMEM);
+ info.flags = 0;
+ info.low_limit = TASK_UNMAPPED_BASE;
+ info.high_limit = TASK_SIZE;
+ addr = vm_unmapped_area(&info);
+ }
+
+ return addr;
+}
+#endif
+
+unsigned long
+get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
+ unsigned long pgoff, unsigned long flags)
+{
+ unsigned long (*get_area)(struct file *, unsigned long,
+ unsigned long, unsigned long, unsigned long);
+
+ unsigned long error = arch_mmap_check(addr, len, flags);
+ if (error)
+ return error;
+
+ /* Careful about overflows.. */
+ if (len > TASK_SIZE)
+ return -ENOMEM;
+
+ get_area = current->mm->get_unmapped_area;
+ if (file) {
+ if (file->f_op->get_unmapped_area)
+ get_area = file->f_op->get_unmapped_area;
+ } else if (flags & MAP_SHARED) {
+ /*
+ * mmap_region() will call shmem_zero_setup() to create a file,
+ * so use shmem's get_unmapped_area in case it can be huge.
+ * do_mmap_pgoff() will clear pgoff, so match alignment.
+ */
+ pgoff = 0;
+ get_area = shmem_get_unmapped_area;
+ }
+
+ addr = get_area(file, addr, len, pgoff, flags);
+ if (IS_ERR_VALUE(addr))
+ return addr;
+
+ if (addr > TASK_SIZE - len)
+ return -ENOMEM;
+ if (offset_in_page(addr))
+ return -EINVAL;
+
+ error = security_mmap_addr(addr);
+ return error ? error : addr;
+}
+
+EXPORT_SYMBOL(get_unmapped_area);
+
+/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
+struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+{
+ struct rb_node *rb_node;
+ struct vm_area_struct *vma;
+
+ /* Check the cache first. */
+ vma = vmacache_find(mm, addr);
+ if (likely(vma))
+ return vma;
+
+ rb_node = mm->mm_rb.rb_node;
+
+ while (rb_node) {
+ struct vm_area_struct *tmp;
+
+ tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
+
+ if (tmp->vm_end > addr) {
+ vma = tmp;
+ if (tmp->vm_start <= addr)
+ break;
+ rb_node = rb_node->rb_left;
+ } else
+ rb_node = rb_node->rb_right;
+ }
+
+ if (vma)
+ vmacache_update(addr, vma);
+ return vma;
+}
+
+EXPORT_SYMBOL(find_vma);
+
+/*
+ * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
+ */
+struct vm_area_struct *
+find_vma_prev(struct mm_struct *mm, unsigned long addr,
+ struct vm_area_struct **pprev)
+{
+ struct vm_area_struct *vma;
+
+ vma = find_vma(mm, addr);
+ if (vma) {
+ *pprev = vma->vm_prev;
+ } else {
+ struct rb_node *rb_node = mm->mm_rb.rb_node;
+ *pprev = NULL;
+ while (rb_node) {
+ *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
+ rb_node = rb_node->rb_right;
+ }
+ }
+ return vma;
+}
+
+/*
+ * Verify that the stack growth is acceptable and
+ * update accounting. This is shared with both the
+ * grow-up and grow-down cases.
+ */
+static int acct_stack_growth(struct vm_area_struct *vma,
+ unsigned long size, unsigned long grow)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long new_start;
+
+ /* address space limit tests */
+ if (!may_expand_vm(mm, vma->vm_flags, grow))
+ return -ENOMEM;
+
+ /* Stack limit test */
+ if (size > rlimit(RLIMIT_STACK))
+ return -ENOMEM;
+
+ /* mlock limit tests */
+ if (vma->vm_flags & VM_LOCKED) {
+ unsigned long locked;
+ unsigned long limit;
+ locked = mm->locked_vm + grow;
+ limit = rlimit(RLIMIT_MEMLOCK);
+ limit >>= PAGE_SHIFT;
+ if (locked > limit && !capable(CAP_IPC_LOCK))
+ return -ENOMEM;
+ }
+
+ /* Check to ensure the stack will not grow into a hugetlb-only region */
+ new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
+ vma->vm_end - size;
+ if (is_hugepage_only_range(vma->vm_mm, new_start, size))
+ return -EFAULT;
+
+ /*
+ * Overcommit.. This must be the final test, as it will
+ * update security statistics.
+ */
+ if (security_vm_enough_memory_mm(mm, grow))
+ return -ENOMEM;
+
+ return 0;
+}
+
+#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
+/*
+ * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
+ * vma is the last one with address > vma->vm_end. Have to extend vma.
+ */
+int expand_upwards(struct vm_area_struct *vma, unsigned long address)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *next;
+ unsigned long gap_addr;
+ int error = 0;
+
+ if (!(vma->vm_flags & VM_GROWSUP))
+ return -EFAULT;
+
+ /* Guard against exceeding limits of the address space. */
+ address &= PAGE_MASK;
+ if (address >= (TASK_SIZE & PAGE_MASK))
+ return -ENOMEM;
+ address += PAGE_SIZE;
+
+ /* Enforce stack_guard_gap */
+ gap_addr = address + stack_guard_gap;
+
+ /* Guard against overflow */
+ if (gap_addr < address || gap_addr > TASK_SIZE)
+ gap_addr = TASK_SIZE;
+
+ next = vma->vm_next;
+ if (next && next->vm_start < gap_addr &&
+ (next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
+ if (!(next->vm_flags & VM_GROWSUP))
+ return -ENOMEM;
+ /* Check that both stack segments have the same anon_vma? */
+ }
+
+ /* We must make sure the anon_vma is allocated. */
+ if (unlikely(anon_vma_prepare(vma)))
+ return -ENOMEM;
+
+ /*
+ * vma->vm_start/vm_end cannot change under us because the caller
+ * is required to hold the mmap_sem in read mode. We need the
+ * anon_vma lock to serialize against concurrent expand_stacks.
+ */
+ anon_vma_lock_write(vma->anon_vma);
+
+ /* Somebody else might have raced and expanded it already */
+ if (address > vma->vm_end) {
+ unsigned long size, grow;
+
+ size = address - vma->vm_start;
+ grow = (address - vma->vm_end) >> PAGE_SHIFT;
+
+ error = -ENOMEM;
+ if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
+ error = acct_stack_growth(vma, size, grow);
+ if (!error) {
+ /*
+ * vma_gap_update() doesn't support concurrent
+ * updates, but we only hold a shared mmap_sem
+ * lock here, so we need to protect against
+ * concurrent vma expansions.
+ * anon_vma_lock_write() doesn't help here, as
+ * we don't guarantee that all growable vmas
+ * in a mm share the same root anon vma.
+ * So, we reuse mm->page_table_lock to guard
+ * against concurrent vma expansions.
+ */
+ spin_lock(&mm->page_table_lock);
+ if (vma->vm_flags & VM_LOCKED)
+ mm->locked_vm += grow;
+ vm_stat_account(mm, vma->vm_flags, grow);
+ anon_vma_interval_tree_pre_update_vma(vma);
+ vma->vm_end = address;
+ anon_vma_interval_tree_post_update_vma(vma);
+ if (vma->vm_next)
+ vma_gap_update(vma->vm_next);
+ else
+ mm->highest_vm_end = vm_end_gap(vma);
+ spin_unlock(&mm->page_table_lock);
+
+ perf_event_mmap(vma);
+ }
+ }
+ }
+ anon_vma_unlock_write(vma->anon_vma);
+ khugepaged_enter_vma_merge(vma, vma->vm_flags);
+ validate_mm(mm);
+ return error;
+}
+#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
+
+/*
+ * vma is the first one with address < vma->vm_start. Have to extend vma.
+ */
+int expand_downwards(struct vm_area_struct *vma,
+ unsigned long address)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *prev;
+ int error;
+
+ address &= PAGE_MASK;
+ error = security_mmap_addr(address);
+ if (error)
+ return error;
+
+ /* Enforce stack_guard_gap */
+ prev = vma->vm_prev;
+ /* Check that both stack segments have the same anon_vma? */
+ if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
+ (prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
+ if (address - prev->vm_end < stack_guard_gap)
+ return -ENOMEM;
+ }
+
+ /* We must make sure the anon_vma is allocated. */
+ if (unlikely(anon_vma_prepare(vma)))
+ return -ENOMEM;
+
+ /*
+ * vma->vm_start/vm_end cannot change under us because the caller
+ * is required to hold the mmap_sem in read mode. We need the
+ * anon_vma lock to serialize against concurrent expand_stacks.
+ */
+ anon_vma_lock_write(vma->anon_vma);
+
+ /* Somebody else might have raced and expanded it already */
+ if (address < vma->vm_start) {
+ unsigned long size, grow;
+
+ size = vma->vm_end - address;
+ grow = (vma->vm_start - address) >> PAGE_SHIFT;
+
+ error = -ENOMEM;
+ if (grow <= vma->vm_pgoff) {
+ error = acct_stack_growth(vma, size, grow);
+ if (!error) {
+ /*
+ * vma_gap_update() doesn't support concurrent
+ * updates, but we only hold a shared mmap_sem
+ * lock here, so we need to protect against
+ * concurrent vma expansions.
+ * anon_vma_lock_write() doesn't help here, as
+ * we don't guarantee that all growable vmas
+ * in a mm share the same root anon vma.
+ * So, we reuse mm->page_table_lock to guard
+ * against concurrent vma expansions.
+ */
+ spin_lock(&mm->page_table_lock);
+ if (vma->vm_flags & VM_LOCKED)
+ mm->locked_vm += grow;
+ vm_stat_account(mm, vma->vm_flags, grow);
+ anon_vma_interval_tree_pre_update_vma(vma);
+ vma->vm_start = address;
+ vma->vm_pgoff -= grow;
+ anon_vma_interval_tree_post_update_vma(vma);
+ vma_gap_update(vma);
+ spin_unlock(&mm->page_table_lock);
+
+ perf_event_mmap(vma);
+ }
+ }
+ }
+ anon_vma_unlock_write(vma->anon_vma);
+ khugepaged_enter_vma_merge(vma, vma->vm_flags);
+ validate_mm(mm);
+ return error;
+}
+
+/* enforced gap between the expanding stack and other mappings. */
+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
+
+static int __init cmdline_parse_stack_guard_gap(char *p)
+{
+ unsigned long val;
+ char *endptr;
+
+ val = simple_strtoul(p, &endptr, 10);
+ if (!*endptr)
+ stack_guard_gap = val << PAGE_SHIFT;
+
+ return 0;
+}
+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
+
+#ifdef CONFIG_STACK_GROWSUP
+int expand_stack(struct vm_area_struct *vma, unsigned long address)
+{
+ return expand_upwards(vma, address);
+}
+
+struct vm_area_struct *
+find_extend_vma(struct mm_struct *mm, unsigned long addr)
+{
+ struct vm_area_struct *vma, *prev;
+
+ addr &= PAGE_MASK;
+ vma = find_vma_prev(mm, addr, &prev);
+ if (vma && (vma->vm_start <= addr))
+ return vma;
+ if (!prev || expand_stack(prev, addr))
+ return NULL;
+ if (prev->vm_flags & VM_LOCKED)
+ populate_vma_page_range(prev, addr, prev->vm_end, NULL);
+ return prev;
+}
+#else
+int expand_stack(struct vm_area_struct *vma, unsigned long address)
+{
+ return expand_downwards(vma, address);
+}
+
+struct vm_area_struct *
+find_extend_vma(struct mm_struct *mm, unsigned long addr)
+{
+ struct vm_area_struct *vma;
+ unsigned long start;
+
+ addr &= PAGE_MASK;
+ vma = find_vma(mm, addr);
+ if (!vma)
+ return NULL;
+ if (vma->vm_start <= addr)
+ return vma;
+ if (!(vma->vm_flags & VM_GROWSDOWN))
+ return NULL;
+ start = vma->vm_start;
+ if (expand_stack(vma, addr))
+ return NULL;
+ if (vma->vm_flags & VM_LOCKED)
+ populate_vma_page_range(vma, addr, start, NULL);
+ return vma;
+}
+#endif
+
+EXPORT_SYMBOL_GPL(find_extend_vma);
+
+/*
+ * Ok - we have the memory areas we should free on the vma list,
+ * so release them, and do the vma updates.
+ *
+ * Called with the mm semaphore held.
+ */
+static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+ unsigned long nr_accounted = 0;
+
+ /* Update high watermark before we lower total_vm */
+ update_hiwater_vm(mm);
+ do {
+ long nrpages = vma_pages(vma);
+
+ if (vma->vm_flags & VM_ACCOUNT)
+ nr_accounted += nrpages;
+ vm_stat_account(mm, vma->vm_flags, -nrpages);
+ vma = remove_vma(vma);
+ } while (vma);
+ vm_unacct_memory(nr_accounted);
+ validate_mm(mm);
+}
+
+/*
+ * Get rid of page table information in the indicated region.
+ *
+ * Called with the mm semaphore held.
+ */
+static void unmap_region(struct mm_struct *mm,
+ struct vm_area_struct *vma, struct vm_area_struct *prev,
+ unsigned long start, unsigned long end)
+{
+ struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
+ struct mmu_gather tlb;
+
+ lru_add_drain();
+ tlb_gather_mmu(&tlb, mm, start, end);
+ update_hiwater_rss(mm);
+ unmap_vmas(&tlb, vma, start, end);
+ free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
+ next ? next->vm_start : USER_PGTABLES_CEILING);
+ tlb_finish_mmu(&tlb, start, end);
+}
+
+/*
+ * Create a list of vma's touched by the unmap, removing them from the mm's
+ * vma list as we go..
+ */
+static void
+detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
+ struct vm_area_struct *prev, unsigned long end)
+{
+ struct vm_area_struct **insertion_point;
+ struct vm_area_struct *tail_vma = NULL;
+
+ insertion_point = (prev ? &prev->vm_next : &mm->mmap);
+ vma->vm_prev = NULL;
+ do {
+ vma_rb_erase(vma, &mm->mm_rb);
+ mm->map_count--;
+ tail_vma = vma;
+ vma = vma->vm_next;
+ } while (vma && vma->vm_start < end);
+ *insertion_point = vma;
+ if (vma) {
+ vma->vm_prev = prev;
+ vma_gap_update(vma);
+ } else
+ mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
+ tail_vma->vm_next = NULL;
+
+ /* Kill the cache */
+ vmacache_invalidate(mm);
+}
+
+/*
+ * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
+ * has already been checked or doesn't make sense to fail.
+ */
+int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr, int new_below)
+{
+ struct vm_area_struct *new;
+ int err;
+
+ if (vma->vm_ops && vma->vm_ops->split) {
+ err = vma->vm_ops->split(vma, addr);
+ if (err)
+ return err;
+ }
+
+ new = vm_area_dup(vma);
+ if (!new)
+ return -ENOMEM;
+
+ if (new_below)
+ new->vm_end = addr;
+ else {
+ new->vm_start = addr;
+ new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
+ }
+
+ err = vma_dup_policy(vma, new);
+ if (err)
+ goto out_free_vma;
+
+ err = anon_vma_clone(new, vma);
+ if (err)
+ goto out_free_mpol;
+
+ if (new->vm_file)
+ get_file(new->vm_file);
+
+ if (new->vm_ops && new->vm_ops->open)
+ new->vm_ops->open(new);
+
+ if (new_below)
+ err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
+ ((addr - new->vm_start) >> PAGE_SHIFT), new);
+ else
+ err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
+
+ /* Success. */
+ if (!err)
+ return 0;
+
+ /* Clean everything up if vma_adjust failed. */
+ if (new->vm_ops && new->vm_ops->close)
+ new->vm_ops->close(new);
+ if (new->vm_file)
+ fput(new->vm_file);
+ unlink_anon_vmas(new);
+ out_free_mpol:
+ mpol_put(vma_policy(new));
+ out_free_vma:
+ vm_area_free(new);
+ return err;
+}
+
+/*
+ * Split a vma into two pieces at address 'addr', a new vma is allocated
+ * either for the first part or the tail.
+ */
+int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long addr, int new_below)
+{
+ if (mm->map_count >= sysctl_max_map_count)
+ return -ENOMEM;
+
+ return __split_vma(mm, vma, addr, new_below);
+}
+
+/* Munmap is split into 2 main parts -- this part which finds
+ * what needs doing, and the areas themselves, which do the
+ * work. This now handles partial unmappings.
+ * Jeremy Fitzhardinge <jeremy@goop.org>
+ */
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+ struct list_head *uf)
+{
+ unsigned long end;
+ struct vm_area_struct *vma, *prev, *last;
+
+ if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
+ return -EINVAL;
+
+ len = PAGE_ALIGN(len);
+ if (len == 0)
+ return -EINVAL;
+
+ /* Find the first overlapping VMA */
+ vma = find_vma(mm, start);
+ if (!vma)
+ return 0;
+ prev = vma->vm_prev;
+ /* we have start < vma->vm_end */
+
+ /* if it doesn't overlap, we have nothing.. */
+ end = start + len;
+ if (vma->vm_start >= end)
+ return 0;
+
+ /*
+ * If we need to split any vma, do it now to save pain later.
+ *
+ * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
+ * unmapped vm_area_struct will remain in use: so lower split_vma
+ * places tmp vma above, and higher split_vma places tmp vma below.
+ */
+ if (start > vma->vm_start) {
+ int error;
+
+ /*
+ * Make sure that map_count on return from munmap() will
+ * not exceed its limit; but let map_count go just above
+ * its limit temporarily, to help free resources as expected.
+ */
+ if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
+ return -ENOMEM;
+
+ error = __split_vma(mm, vma, start, 0);
+ if (error)
+ return error;
+ prev = vma;
+ }
+
+ /* Does it split the last one? */
+ last = find_vma(mm, end);
+ if (last && end > last->vm_start) {
+ int error = __split_vma(mm, last, end, 1);
+ if (error)
+ return error;
+ }
+ vma = prev ? prev->vm_next : mm->mmap;
+
+ if (unlikely(uf)) {
+ /*
+ * If userfaultfd_unmap_prep returns an error the vmas
+ * will remain splitted, but userland will get a
+ * highly unexpected error anyway. This is no
+ * different than the case where the first of the two
+ * __split_vma fails, but we don't undo the first
+ * split, despite we could. This is unlikely enough
+ * failure that it's not worth optimizing it for.
+ */
+ int error = userfaultfd_unmap_prep(vma, start, end, uf);
+ if (error)
+ return error;
+ }
+
+ /*
+ * unlock any mlock()ed ranges before detaching vmas
+ */
+ if (mm->locked_vm) {
+ struct vm_area_struct *tmp = vma;
+ while (tmp && tmp->vm_start < end) {
+ if (tmp->vm_flags & VM_LOCKED) {
+ mm->locked_vm -= vma_pages(tmp);
+ munlock_vma_pages_all(tmp);
+ }
+ tmp = tmp->vm_next;
+ }
+ }
+
+ /*
+ * Remove the vma's, and unmap the actual pages
+ */
+ detach_vmas_to_be_unmapped(mm, vma, prev, end);
+ unmap_region(mm, vma, prev, start, end);
+
+ arch_unmap(mm, vma, start, end);
+
+ /* Fix up all other VM information */
+ remove_vma_list(mm, vma);
+
+ return 0;
+}
+
+int vm_munmap(unsigned long start, size_t len)
+{
+ int ret;
+ struct mm_struct *mm = current->mm;
+ LIST_HEAD(uf);
+
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
+ ret = do_munmap(mm, start, len, &uf);
+ up_write(&mm->mmap_sem);
+ userfaultfd_unmap_complete(mm, &uf);
+ return ret;
+}
+EXPORT_SYMBOL(vm_munmap);
+
+SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
+{
+ profile_munmap(addr);
+ return vm_munmap(addr, len);
+}
+
+
+/*
+ * Emulation of deprecated remap_file_pages() syscall.
+ */
+SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
+ unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
+{
+
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long populate = 0;
+ unsigned long ret = -EINVAL;
+ struct file *file;
+
+ pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
+ current->comm, current->pid);
+
+ if (prot)
+ return ret;
+ start = start & PAGE_MASK;
+ size = size & PAGE_MASK;
+
+ if (start + size <= start)
+ return ret;
+
+ /* Does pgoff wrap? */
+ if (pgoff + (size >> PAGE_SHIFT) < pgoff)
+ return ret;
+
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
+ vma = find_vma(mm, start);
+
+ if (!vma || !(vma->vm_flags & VM_SHARED))
+ goto out;
+
+ if (start < vma->vm_start)
+ goto out;
+
+ if (start + size > vma->vm_end) {
+ struct vm_area_struct *next;
+
+ for (next = vma->vm_next; next; next = next->vm_next) {
+ /* hole between vmas ? */
+ if (next->vm_start != next->vm_prev->vm_end)
+ goto out;
+
+ if (next->vm_file != vma->vm_file)
+ goto out;
+
+ if (next->vm_flags != vma->vm_flags)
+ goto out;
+
+ if (start + size <= next->vm_end)
+ break;
+ }
+
+ if (!next)
+ goto out;
+ }
+
+ prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
+ prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
+ prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
+
+ flags &= MAP_NONBLOCK;
+ flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
+ if (vma->vm_flags & VM_LOCKED) {
+ struct vm_area_struct *tmp;
+ flags |= MAP_LOCKED;
+
+ /* drop PG_Mlocked flag for over-mapped range */
+ for (tmp = vma; tmp->vm_start >= start + size;
+ tmp = tmp->vm_next) {
+ /*
+ * Split pmd and munlock page on the border
+ * of the range.
+ */
+ vma_adjust_trans_huge(tmp, start, start + size, 0);
+
+ munlock_vma_pages_range(tmp,
+ max(tmp->vm_start, start),
+ min(tmp->vm_end, start + size));
+ }
+ }
+
+ file = get_file(vma->vm_file);
+ ret = do_mmap_pgoff(vma->vm_file, start, size,
+ prot, flags, pgoff, &populate, NULL);
+ fput(file);
+out:
+ up_write(&mm->mmap_sem);
+ if (populate)
+ mm_populate(ret, populate);
+ if (!IS_ERR_VALUE(ret))
+ ret = 0;
+ return ret;
+}
+
+static inline void verify_mm_writelocked(struct mm_struct *mm)
+{
+#ifdef CONFIG_DEBUG_VM
+ if (unlikely(down_read_trylock(&mm->mmap_sem))) {
+ WARN_ON(1);
+ up_read(&mm->mmap_sem);
+ }
+#endif
+}
+
+/*
+ * this is really a simplified "do_mmap". it only handles
+ * anonymous maps. eventually we may be able to do some
+ * brk-specific accounting here.
+ */
+static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf)
+{
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma, *prev;
+ struct rb_node **rb_link, *rb_parent;
+ pgoff_t pgoff = addr >> PAGE_SHIFT;
+ int error;
+
+ /* Until we need other flags, refuse anything except VM_EXEC. */
+ if ((flags & (~VM_EXEC)) != 0)
+ return -EINVAL;
+ flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
+
+ error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
+ if (offset_in_page(error))
+ return error;
+
+ error = mlock_future_check(mm, mm->def_flags, len);
+ if (error)
+ return error;
+
+ /*
+ * mm->mmap_sem is required to protect against another thread
+ * changing the mappings in case we sleep.
+ */
+ verify_mm_writelocked(mm);
+
+ /*
+ * Clear old maps. this also does some error checking for us
+ */
+ while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
+ &rb_parent)) {
+ if (do_munmap(mm, addr, len, uf))
+ return -ENOMEM;
+ }
+
+ /* Check against address space limits *after* clearing old maps... */
+ if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
+ return -ENOMEM;
+
+ if (mm->map_count > sysctl_max_map_count)
+ return -ENOMEM;
+
+ if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
+ return -ENOMEM;
+
+ /* Can we just expand an old private anonymous mapping? */
+ vma = vma_merge(mm, prev, addr, addr + len, flags,
+ NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
+ if (vma)
+ goto out;
+
+ /*
+ * create a vma struct for an anonymous mapping
+ */
+ vma = vm_area_alloc(mm);
+ if (!vma) {
+ vm_unacct_memory(len >> PAGE_SHIFT);
+ return -ENOMEM;
+ }
+
+ vma_set_anonymous(vma);
+ vma->vm_start = addr;
+ vma->vm_end = addr + len;
+ vma->vm_pgoff = pgoff;
+ vma->vm_flags = flags;
+ vma->vm_page_prot = vm_get_page_prot(flags);
+ vma_link(mm, vma, prev, rb_link, rb_parent);
+out:
+ perf_event_mmap(vma);
+ mm->total_vm += len >> PAGE_SHIFT;
+ mm->data_vm += len >> PAGE_SHIFT;
+ if (flags & VM_LOCKED)
+ mm->locked_vm += (len >> PAGE_SHIFT);
+ vma->vm_flags |= VM_SOFTDIRTY;
+ return 0;
+}
+
+int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long len;
+ int ret;
+ bool populate;
+ LIST_HEAD(uf);
+
+ len = PAGE_ALIGN(request);
+ if (len < request)
+ return -ENOMEM;
+ if (!len)
+ return 0;
+
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
+ ret = do_brk_flags(addr, len, flags, &uf);
+ populate = ((mm->def_flags & VM_LOCKED) != 0);
+ up_write(&mm->mmap_sem);
+ userfaultfd_unmap_complete(mm, &uf);
+ if (populate && !ret)
+ mm_populate(addr, len);
+ return ret;
+}
+EXPORT_SYMBOL(vm_brk_flags);
+
+int vm_brk(unsigned long addr, unsigned long len)
+{
+ return vm_brk_flags(addr, len, 0);
+}
+EXPORT_SYMBOL(vm_brk);
+
+/* Release all mmaps. */
+void exit_mmap(struct mm_struct *mm)
+{
+ struct mmu_gather tlb;
+ struct vm_area_struct *vma;
+ unsigned long nr_accounted = 0;
+
+ /* mm's last user has gone, and its about to be pulled down */
+ mmu_notifier_release(mm);
+
+ if (unlikely(mm_is_oom_victim(mm))) {
+ /*
+ * Manually reap the mm to free as much memory as possible.
+ * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
+ * this mm from further consideration. Taking mm->mmap_sem for
+ * write after setting MMF_OOM_SKIP will guarantee that the oom
+ * reaper will not run on this mm again after mmap_sem is
+ * dropped.
+ *
+ * Nothing can be holding mm->mmap_sem here and the above call
+ * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
+ * __oom_reap_task_mm() will not block.
+ *
+ * This needs to be done before calling munlock_vma_pages_all(),
+ * which clears VM_LOCKED, otherwise the oom reaper cannot
+ * reliably test it.
+ */
+ (void)__oom_reap_task_mm(mm);
+
+ set_bit(MMF_OOM_SKIP, &mm->flags);
+ down_write(&mm->mmap_sem);
+ up_write(&mm->mmap_sem);
+ }
+
+ if (mm->locked_vm) {
+ vma = mm->mmap;
+ while (vma) {
+ if (vma->vm_flags & VM_LOCKED)
+ munlock_vma_pages_all(vma);
+ vma = vma->vm_next;
+ }
+ }
+
+ arch_exit_mmap(mm);
+
+ vma = mm->mmap;
+ if (!vma) /* Can happen if dup_mmap() received an OOM */
+ return;
+
+ lru_add_drain();
+ flush_cache_mm(mm);
+ tlb_gather_mmu(&tlb, mm, 0, -1);
+ /* update_hiwater_rss(mm) here? but nobody should be looking */
+ /* Use -1 here to ensure all VMAs in the mm are unmapped */
+ unmap_vmas(&tlb, vma, 0, -1);
+ free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
+ tlb_finish_mmu(&tlb, 0, -1);
+
+ /*
+ * Walk the list again, actually closing and freeing it,
+ * with preemption enabled, without holding any MM locks.
+ */
+ while (vma) {
+ if (vma->vm_flags & VM_ACCOUNT)
+ nr_accounted += vma_pages(vma);
+ vma = remove_vma(vma);
+ }
+ vm_unacct_memory(nr_accounted);
+}
+
+/* Insert vm structure into process list sorted by address
+ * and into the inode's i_mmap tree. If vm_file is non-NULL
+ * then i_mmap_rwsem is taken here.
+ */
+int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
+{
+ struct vm_area_struct *prev;
+ struct rb_node **rb_link, *rb_parent;
+
+ if (find_vma_links(mm, vma->vm_start, vma->vm_end,
+ &prev, &rb_link, &rb_parent))
+ return -ENOMEM;
+ if ((vma->vm_flags & VM_ACCOUNT) &&
+ security_vm_enough_memory_mm(mm, vma_pages(vma)))
+ return -ENOMEM;
+
+ /*
+ * The vm_pgoff of a purely anonymous vma should be irrelevant
+ * until its first write fault, when page's anon_vma and index
+ * are set. But now set the vm_pgoff it will almost certainly
+ * end up with (unless mremap moves it elsewhere before that
+ * first wfault), so /proc/pid/maps tells a consistent story.
+ *
+ * By setting it to reflect the virtual start address of the
+ * vma, merges and splits can happen in a seamless way, just
+ * using the existing file pgoff checks and manipulations.
+ * Similarly in do_mmap_pgoff and in do_brk.
+ */
+ if (vma_is_anonymous(vma)) {
+ BUG_ON(vma->anon_vma);
+ vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
+ }
+
+ vma_link(mm, vma, prev, rb_link, rb_parent);
+ return 0;
+}
+
+/*
+ * Copy the vma structure to a new location in the same mm,
+ * prior to moving page table entries, to effect an mremap move.
+ */
+struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
+ unsigned long addr, unsigned long len, pgoff_t pgoff,
+ bool *need_rmap_locks)
+{
+ struct vm_area_struct *vma = *vmap;
+ unsigned long vma_start = vma->vm_start;
+ struct mm_struct *mm = vma->vm_mm;
+ struct vm_area_struct *new_vma, *prev;
+ struct rb_node **rb_link, *rb_parent;
+ bool faulted_in_anon_vma = true;
+
+ /*
+ * If anonymous vma has not yet been faulted, update new pgoff
+ * to match new location, to increase its chance of merging.
+ */
+ if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
+ pgoff = addr >> PAGE_SHIFT;
+ faulted_in_anon_vma = false;
+ }
+
+ if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
+ return NULL; /* should never get here */
+ new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
+ vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+ vma->vm_userfaultfd_ctx);
+ if (new_vma) {
+ /*
+ * Source vma may have been merged into new_vma
+ */
+ if (unlikely(vma_start >= new_vma->vm_start &&
+ vma_start < new_vma->vm_end)) {
+ /*
+ * The only way we can get a vma_merge with
+ * self during an mremap is if the vma hasn't
+ * been faulted in yet and we were allowed to
+ * reset the dst vma->vm_pgoff to the
+ * destination address of the mremap to allow
+ * the merge to happen. mremap must change the
+ * vm_pgoff linearity between src and dst vmas
+ * (in turn preventing a vma_merge) to be
+ * safe. It is only safe to keep the vm_pgoff
+ * linear if there are no pages mapped yet.
+ */
+ VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
+ *vmap = vma = new_vma;
+ }
+ *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
+ } else {
+ new_vma = vm_area_dup(vma);
+ if (!new_vma)
+ goto out;
+ new_vma->vm_start = addr;
+ new_vma->vm_end = addr + len;
+ new_vma->vm_pgoff = pgoff;
+ if (vma_dup_policy(vma, new_vma))
+ goto out_free_vma;
+ if (anon_vma_clone(new_vma, vma))
+ goto out_free_mempol;
+ if (new_vma->vm_file)
+ get_file(new_vma->vm_file);
+ if (new_vma->vm_ops && new_vma->vm_ops->open)
+ new_vma->vm_ops->open(new_vma);
+ vma_link(mm, new_vma, prev, rb_link, rb_parent);
+ *need_rmap_locks = false;
+ }
+ return new_vma;
+
+out_free_mempol:
+ mpol_put(vma_policy(new_vma));
+out_free_vma:
+ vm_area_free(new_vma);
+out:
+ return NULL;
+}
+
+/*
+ * Return true if the calling process may expand its vm space by the passed
+ * number of pages
+ */
+bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
+{
+ if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
+ return false;
+
+ if (is_data_mapping(flags) &&
+ mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
+ /* Workaround for Valgrind */
+ if (rlimit(RLIMIT_DATA) == 0 &&
+ mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
+ return true;
+
+ pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
+ current->comm, current->pid,
+ (mm->data_vm + npages) << PAGE_SHIFT,
+ rlimit(RLIMIT_DATA),
+ ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
+
+ if (!ignore_rlimit_data)
+ return false;
+ }
+
+ return true;
+}
+
+void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
+{
+ mm->total_vm += npages;
+
+ if (is_exec_mapping(flags))
+ mm->exec_vm += npages;
+ else if (is_stack_mapping(flags))
+ mm->stack_vm += npages;
+ else if (is_data_mapping(flags))
+ mm->data_vm += npages;
+}
+
+static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
+
+/*
+ * Having a close hook prevents vma merging regardless of flags.
+ */
+static void special_mapping_close(struct vm_area_struct *vma)
+{
+}
+
+static const char *special_mapping_name(struct vm_area_struct *vma)
+{
+ return ((struct vm_special_mapping *)vma->vm_private_data)->name;
+}
+
+static int special_mapping_mremap(struct vm_area_struct *new_vma)
+{
+ struct vm_special_mapping *sm = new_vma->vm_private_data;
+
+ if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
+ return -EFAULT;
+
+ if (sm->mremap)
+ return sm->mremap(sm, new_vma);
+
+ return 0;
+}
+
+static const struct vm_operations_struct special_mapping_vmops = {
+ .close = special_mapping_close,
+ .fault = special_mapping_fault,
+ .mremap = special_mapping_mremap,
+ .name = special_mapping_name,
+};
+
+static const struct vm_operations_struct legacy_special_mapping_vmops = {
+ .close = special_mapping_close,
+ .fault = special_mapping_fault,
+};
+
+static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ pgoff_t pgoff;
+ struct page **pages;
+
+ if (vma->vm_ops == &legacy_special_mapping_vmops) {
+ pages = vma->vm_private_data;
+ } else {
+ struct vm_special_mapping *sm = vma->vm_private_data;
+
+ if (sm->fault)
+ return sm->fault(sm, vmf->vma, vmf);
+
+ pages = sm->pages;
+ }
+
+ for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
+ pgoff--;
+
+ if (*pages) {
+ struct page *page = *pages;
+ get_page(page);
+ vmf->page = page;
+ return 0;
+ }
+
+ return VM_FAULT_SIGBUS;
+}
+
+static struct vm_area_struct *__install_special_mapping(
+ struct mm_struct *mm,
+ unsigned long addr, unsigned long len,
+ unsigned long vm_flags, void *priv,
+ const struct vm_operations_struct *ops)
+{
+ int ret;
+ struct vm_area_struct *vma;
+
+ vma = vm_area_alloc(mm);
+ if (unlikely(vma == NULL))
+ return ERR_PTR(-ENOMEM);
+
+ vma->vm_start = addr;
+ vma->vm_end = addr + len;
+
+ vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
+ vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+
+ vma->vm_ops = ops;
+ vma->vm_private_data = priv;
+
+ ret = insert_vm_struct(mm, vma);
+ if (ret)
+ goto out;
+
+ vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
+
+ perf_event_mmap(vma);
+
+ return vma;
+
+out:
+ vm_area_free(vma);
+ return ERR_PTR(ret);
+}
+
+bool vma_is_special_mapping(const struct vm_area_struct *vma,
+ const struct vm_special_mapping *sm)
+{
+ return vma->vm_private_data == sm &&
+ (vma->vm_ops == &special_mapping_vmops ||
+ vma->vm_ops == &legacy_special_mapping_vmops);
+}
+
+/*
+ * Called with mm->mmap_sem held for writing.
+ * Insert a new vma covering the given region, with the given flags.
+ * Its pages are supplied by the given array of struct page *.
+ * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
+ * The region past the last page supplied will always produce SIGBUS.
+ * The array pointer and the pages it points to are assumed to stay alive
+ * for as long as this mapping might exist.
+ */
+struct vm_area_struct *_install_special_mapping(
+ struct mm_struct *mm,
+ unsigned long addr, unsigned long len,
+ unsigned long vm_flags, const struct vm_special_mapping *spec)
+{
+ return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
+ &special_mapping_vmops);
+}
+
+int install_special_mapping(struct mm_struct *mm,
+ unsigned long addr, unsigned long len,
+ unsigned long vm_flags, struct page **pages)
+{
+ struct vm_area_struct *vma = __install_special_mapping(
+ mm, addr, len, vm_flags, (void *)pages,
+ &legacy_special_mapping_vmops);
+
+ return PTR_ERR_OR_ZERO(vma);
+}
+
+static DEFINE_MUTEX(mm_all_locks_mutex);
+
+static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
+{
+ if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
+ /*
+ * The LSB of head.next can't change from under us
+ * because we hold the mm_all_locks_mutex.
+ */
+ down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
+ /*
+ * We can safely modify head.next after taking the
+ * anon_vma->root->rwsem. If some other vma in this mm shares
+ * the same anon_vma we won't take it again.
+ *
+ * No need of atomic instructions here, head.next
+ * can't change from under us thanks to the
+ * anon_vma->root->rwsem.
+ */
+ if (__test_and_set_bit(0, (unsigned long *)
+ &anon_vma->root->rb_root.rb_root.rb_node))
+ BUG();
+ }
+}
+
+static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
+{
+ if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
+ /*
+ * AS_MM_ALL_LOCKS can't change from under us because
+ * we hold the mm_all_locks_mutex.
+ *
+ * Operations on ->flags have to be atomic because
+ * even if AS_MM_ALL_LOCKS is stable thanks to the
+ * mm_all_locks_mutex, there may be other cpus
+ * changing other bitflags in parallel to us.
+ */
+ if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
+ BUG();
+ down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
+ }
+}
+
+/*
+ * This operation locks against the VM for all pte/vma/mm related
+ * operations that could ever happen on a certain mm. This includes
+ * vmtruncate, try_to_unmap, and all page faults.
+ *
+ * The caller must take the mmap_sem in write mode before calling
+ * mm_take_all_locks(). The caller isn't allowed to release the
+ * mmap_sem until mm_drop_all_locks() returns.
+ *
+ * mmap_sem in write mode is required in order to block all operations
+ * that could modify pagetables and free pages without need of
+ * altering the vma layout. It's also needed in write mode to avoid new
+ * anon_vmas to be associated with existing vmas.
+ *
+ * A single task can't take more than one mm_take_all_locks() in a row
+ * or it would deadlock.
+ *
+ * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
+ * mapping->flags avoid to take the same lock twice, if more than one
+ * vma in this mm is backed by the same anon_vma or address_space.
+ *
+ * We take locks in following order, accordingly to comment at beginning
+ * of mm/rmap.c:
+ * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
+ * hugetlb mapping);
+ * - all i_mmap_rwsem locks;
+ * - all anon_vma->rwseml
+ *
+ * We can take all locks within these types randomly because the VM code
+ * doesn't nest them and we protected from parallel mm_take_all_locks() by
+ * mm_all_locks_mutex.
+ *
+ * mm_take_all_locks() and mm_drop_all_locks are expensive operations
+ * that may have to take thousand of locks.
+ *
+ * mm_take_all_locks() can fail if it's interrupted by signals.
+ */
+int mm_take_all_locks(struct mm_struct *mm)
+{
+ struct vm_area_struct *vma;
+ struct anon_vma_chain *avc;
+
+ BUG_ON(down_read_trylock(&mm->mmap_sem));
+
+ mutex_lock(&mm_all_locks_mutex);
+
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (signal_pending(current))
+ goto out_unlock;
+ if (vma->vm_file && vma->vm_file->f_mapping &&
+ is_vm_hugetlb_page(vma))
+ vm_lock_mapping(mm, vma->vm_file->f_mapping);
+ }
+
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (signal_pending(current))
+ goto out_unlock;
+ if (vma->vm_file && vma->vm_file->f_mapping &&
+ !is_vm_hugetlb_page(vma))
+ vm_lock_mapping(mm, vma->vm_file->f_mapping);
+ }
+
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (signal_pending(current))
+ goto out_unlock;
+ if (vma->anon_vma)
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ vm_lock_anon_vma(mm, avc->anon_vma);
+ }
+
+ return 0;
+
+out_unlock:
+ mm_drop_all_locks(mm);
+ return -EINTR;
+}
+
+static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
+{
+ if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
+ /*
+ * The LSB of head.next can't change to 0 from under
+ * us because we hold the mm_all_locks_mutex.
+ *
+ * We must however clear the bitflag before unlocking
+ * the vma so the users using the anon_vma->rb_root will
+ * never see our bitflag.
+ *
+ * No need of atomic instructions here, head.next
+ * can't change from under us until we release the
+ * anon_vma->root->rwsem.
+ */
+ if (!__test_and_clear_bit(0, (unsigned long *)
+ &anon_vma->root->rb_root.rb_root.rb_node))
+ BUG();
+ anon_vma_unlock_write(anon_vma);
+ }
+}
+
+static void vm_unlock_mapping(struct address_space *mapping)
+{
+ if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
+ /*
+ * AS_MM_ALL_LOCKS can't change to 0 from under us
+ * because we hold the mm_all_locks_mutex.
+ */
+ i_mmap_unlock_write(mapping);
+ if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
+ &mapping->flags))
+ BUG();
+ }
+}
+
+/*
+ * The mmap_sem cannot be released by the caller until
+ * mm_drop_all_locks() returns.
+ */
+void mm_drop_all_locks(struct mm_struct *mm)
+{
+ struct vm_area_struct *vma;
+ struct anon_vma_chain *avc;
+
+ BUG_ON(down_read_trylock(&mm->mmap_sem));
+ BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
+
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (vma->anon_vma)
+ list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
+ vm_unlock_anon_vma(avc->anon_vma);
+ if (vma->vm_file && vma->vm_file->f_mapping)
+ vm_unlock_mapping(vma->vm_file->f_mapping);
+ }
+
+ mutex_unlock(&mm_all_locks_mutex);
+}
+
+/*
+ * initialise the percpu counter for VM
+ */
+void __init mmap_init(void)
+{
+ int ret;
+
+ ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
+ VM_BUG_ON(ret);
+}
+
+/*
+ * Initialise sysctl_user_reserve_kbytes.
+ *
+ * This is intended to prevent a user from starting a single memory hogging
+ * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
+ * mode.
+ *
+ * The default value is min(3% of free memory, 128MB)
+ * 128MB is enough to recover with sshd/login, bash, and top/kill.
+ */
+static int init_user_reserve(void)
+{
+ unsigned long free_kbytes;
+
+ free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+ sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
+ return 0;
+}
+subsys_initcall(init_user_reserve);
+
+/*
+ * Initialise sysctl_admin_reserve_kbytes.
+ *
+ * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
+ * to log in and kill a memory hogging process.
+ *
+ * Systems with more than 256MB will reserve 8MB, enough to recover
+ * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
+ * only reserve 3% of free pages by default.
+ */
+static int init_admin_reserve(void)
+{
+ unsigned long free_kbytes;
+
+ free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+ sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
+ return 0;
+}
+subsys_initcall(init_admin_reserve);
+
+/*
+ * Reinititalise user and admin reserves if memory is added or removed.
+ *
+ * The default user reserve max is 128MB, and the default max for the
+ * admin reserve is 8MB. These are usually, but not always, enough to
+ * enable recovery from a memory hogging process using login/sshd, a shell,
+ * and tools like top. It may make sense to increase or even disable the
+ * reserve depending on the existence of swap or variations in the recovery
+ * tools. So, the admin may have changed them.
+ *
+ * If memory is added and the reserves have been eliminated or increased above
+ * the default max, then we'll trust the admin.
+ *
+ * If memory is removed and there isn't enough free memory, then we
+ * need to reset the reserves.
+ *
+ * Otherwise keep the reserve set by the admin.
+ */
+static int reserve_mem_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ unsigned long tmp, free_kbytes;
+
+ switch (action) {
+ case MEM_ONLINE:
+ /* Default max is 128MB. Leave alone if modified by operator. */
+ tmp = sysctl_user_reserve_kbytes;
+ if (0 < tmp && tmp < (1UL << 17))
+ init_user_reserve();
+
+ /* Default max is 8MB. Leave alone if modified by operator. */
+ tmp = sysctl_admin_reserve_kbytes;
+ if (0 < tmp && tmp < (1UL << 13))
+ init_admin_reserve();
+
+ break;
+ case MEM_OFFLINE:
+ free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
+
+ if (sysctl_user_reserve_kbytes > free_kbytes) {
+ init_user_reserve();
+ pr_info("vm.user_reserve_kbytes reset to %lu\n",
+ sysctl_user_reserve_kbytes);
+ }
+
+ if (sysctl_admin_reserve_kbytes > free_kbytes) {
+ init_admin_reserve();
+ pr_info("vm.admin_reserve_kbytes reset to %lu\n",
+ sysctl_admin_reserve_kbytes);
+ }
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block reserve_mem_nb = {
+ .notifier_call = reserve_mem_notifier,
+};
+
+static int __meminit init_reserve_notifier(void)
+{
+ if (register_hotmemory_notifier(&reserve_mem_nb))
+ pr_err("Failed registering memory add/remove notifier for admin reserve\n");
+
+ return 0;
+}
+subsys_initcall(init_reserve_notifier);