Update Linux to v5.10.109

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz

Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index ebb0551..c5b0236 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -43,6 +43,8 @@
 #include <linux/sched.h>
 #include <linux/cred.h>
 #include <linux/errno.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
 #include <linux/mm.h>
 #include <linux/memblock.h>
 #include <linux/pagemap.h>
@@ -56,10 +58,9 @@
 #include <linux/percpu-defs.h>
 #include <linux/slab.h>
 #include <linux/sysctl.h>
+#include <linux/moduleparam.h>
 
 #include <asm/page.h>
-#include <asm/pgalloc.h>
-#include <asm/pgtable.h>
 #include <asm/tlb.h>
 
 #include <asm/xen/hypervisor.h>
@@ -73,6 +74,12 @@
 #include <xen/page.h>
 #include <xen/mem-reservation.h>
 
+#undef MODULE_PARAM_PREFIX
+#define MODULE_PARAM_PREFIX "xen."
+
+static uint __read_mostly balloon_boot_timeout = 180;
+module_param(balloon_boot_timeout, uint, 0444);
+
 static int xen_hotplug_unpopulated;
 
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
@@ -117,7 +124,7 @@
 #define EXTENT_ORDER (fls(XEN_PFN_PER_PAGE) - 1)
 
 /*
- * balloon_process() state:
+ * balloon_thread() state:
  *
  * BP_DONE: done or nothing to do,
  * BP_WAIT: wait to be rescheduled,
@@ -125,13 +132,15 @@
  * BP_ECANCELED: error, balloon operation canceled.
  */
 
-enum bp_state {
+static enum bp_state {
 	BP_DONE,
 	BP_WAIT,
 	BP_EAGAIN,
 	BP_ECANCELED
-};
+} balloon_state = BP_DONE;
 
+/* Main waiting point for xen-balloon thread. */
+static DECLARE_WAIT_QUEUE_HEAD(balloon_thread_wq);
 
 static DEFINE_MUTEX(balloon_mutex);
 
@@ -146,10 +155,6 @@
 static LIST_HEAD(ballooned_pages);
 static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
 
-/* Main work function, always executed in process context. */
-static void balloon_process(struct work_struct *work);
-static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
-
 /* When ballooning out (allocating memory to return to Xen) we don't really
    want the kernel to try too hard since that can trigger the oom killer. */
 #define GFP_BALLOON \
@@ -201,18 +206,15 @@
 	return list_entry(next, struct page, lru);
 }
 
-static enum bp_state update_schedule(enum bp_state state)
+static void update_schedule(void)
 {
-	if (state == BP_WAIT)
-		return BP_WAIT;
+	if (balloon_state == BP_WAIT || balloon_state == BP_ECANCELED)
+		return;
 
-	if (state == BP_ECANCELED)
-		return BP_ECANCELED;
-
-	if (state == BP_DONE) {
+	if (balloon_state == BP_DONE) {
 		balloon_stats.schedule_delay = 1;
 		balloon_stats.retry_count = 1;
-		return BP_DONE;
+		return;
 	}
 
 	++balloon_stats.retry_count;
@@ -221,7 +223,8 @@
 			balloon_stats.retry_count > balloon_stats.max_retry_count) {
 		balloon_stats.schedule_delay = 1;
 		balloon_stats.retry_count = 1;
-		return BP_ECANCELED;
+		balloon_state = BP_ECANCELED;
+		return;
 	}
 
 	balloon_stats.schedule_delay <<= 1;
@@ -229,7 +232,7 @@
 	if (balloon_stats.schedule_delay > balloon_stats.max_schedule_delay)
 		balloon_stats.schedule_delay = balloon_stats.max_schedule_delay;
 
-	return BP_EAGAIN;
+	balloon_state = BP_EAGAIN;
 }
 
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
@@ -267,20 +270,6 @@
 		return NULL;
 	}
 
-#ifdef CONFIG_SPARSEMEM
-	{
-		unsigned long limit = 1UL << (MAX_PHYSMEM_BITS - PAGE_SHIFT);
-		unsigned long pfn = res->start >> PAGE_SHIFT;
-
-		if (pfn > limit) {
-			pr_err("New System RAM resource outside addressable RAM (%lu > %lu)\n",
-			       pfn, limit);
-			release_memory_resource(res);
-			return NULL;
-		}
-	}
-#endif
-
 	return res;
 }
 
@@ -347,7 +336,7 @@
 	mutex_unlock(&balloon_mutex);
 	/* add_memory_resource() requires the device_hotplug lock */
 	lock_device_hotplug();
-	rc = add_memory_resource(nid, resource);
+	rc = add_memory_resource(nid, resource, MEMHP_MERGE_RESOURCE);
 	unlock_device_hotplug();
 	mutex_lock(&balloon_mutex);
 
@@ -374,7 +363,6 @@
 	mutex_lock(&balloon_mutex);
 	for (i = 0; i < size; i++) {
 		p = pfn_to_page(start_pfn + i);
-		__online_page_set_limits(p);
 		balloon_append(p);
 	}
 	mutex_unlock(&balloon_mutex);
@@ -383,7 +371,7 @@
 static int xen_memory_notifier(struct notifier_block *nb, unsigned long val, void *v)
 {
 	if (val == MEM_ONLINE)
-		schedule_delayed_work(&balloon_worker, 0);
+		wake_up(&balloon_thread_wq);
 
 	return NOTIFY_OK;
 }
@@ -508,50 +496,79 @@
 }
 
 /*
- * As this is a work item it is guaranteed to run as a single instance only.
+ * Stop waiting if either state is BP_DONE and ballooning action is
+ * needed, or if the credit has changed while state is not BP_DONE.
+ */
+static bool balloon_thread_cond(long credit)
+{
+	if (balloon_state == BP_DONE)
+		credit = 0;
+
+	return current_credit() != credit || kthread_should_stop();
+}
+
+/*
+ * As this is a kthread it is guaranteed to run as a single instance only.
  * We may of course race updates of the target counts (which are protected
  * by the balloon lock), or with changes to the Xen hard limit, but we will
  * recover from these in time.
  */
-static void balloon_process(struct work_struct *work)
+static int balloon_thread(void *unused)
 {
-	enum bp_state state = BP_DONE;
 	long credit;
+	unsigned long timeout;
 
+	set_freezable();
+	for (;;) {
+		switch (balloon_state) {
+		case BP_DONE:
+		case BP_ECANCELED:
+			timeout = 3600 * HZ;
+			break;
+		case BP_EAGAIN:
+			timeout = balloon_stats.schedule_delay * HZ;
+			break;
+		case BP_WAIT:
+			timeout = HZ;
+			break;
+		}
 
-	do {
+		credit = current_credit();
+
+		wait_event_freezable_timeout(balloon_thread_wq,
+			balloon_thread_cond(credit), timeout);
+
+		if (kthread_should_stop())
+			return 0;
+
 		mutex_lock(&balloon_mutex);
 
 		credit = current_credit();
 
 		if (credit > 0) {
 			if (balloon_is_inflated())
-				state = increase_reservation(credit);
+				balloon_state = increase_reservation(credit);
 			else
-				state = reserve_additional_memory();
+				balloon_state = reserve_additional_memory();
 		}
 
 		if (credit < 0) {
 			long n_pages;
 
 			n_pages = min(-credit, si_mem_available());
-			state = decrease_reservation(n_pages, GFP_BALLOON);
-			if (state == BP_DONE && n_pages != -credit &&
+			balloon_state = decrease_reservation(n_pages,
+							     GFP_BALLOON);
+			if (balloon_state == BP_DONE && n_pages != -credit &&
 			    n_pages < totalreserve_pages)
-				state = BP_EAGAIN;
+				balloon_state = BP_EAGAIN;
 		}
 
-		state = update_schedule(state);
+		update_schedule();
 
 		mutex_unlock(&balloon_mutex);
 
 		cond_resched();
-
-	} while (credit && state == BP_DONE);
-
-	/* Schedule more work if there is some still to be done. */
-	if (state == BP_EAGAIN)
-		schedule_delayed_work(&balloon_worker, balloon_stats.schedule_delay * HZ);
+	}
 }
 
 /* Resets the Xen limit, sets new target, and kicks off processing. */
@@ -559,7 +576,7 @@
 {
 	/* No need for lock. Not read-modify-write updates. */
 	balloon_stats.target_pages = target;
-	schedule_delayed_work(&balloon_worker, 0);
+	wake_up(&balloon_thread_wq);
 }
 EXPORT_SYMBOL_GPL(balloon_set_new_target);
 
@@ -664,13 +681,13 @@
 
 	/* The balloon may be too large now. Shrink it if needed. */
 	if (current_credit())
-		schedule_delayed_work(&balloon_worker, 0);
+		wake_up(&balloon_thread_wq);
 
 	mutex_unlock(&balloon_mutex);
 }
 EXPORT_SYMBOL(free_xenballooned_pages);
 
-#ifdef CONFIG_XEN_PV
+#if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
 static void __init balloon_add_region(unsigned long start_pfn,
 				      unsigned long pages)
 {
@@ -696,6 +713,8 @@
 
 static int __init balloon_init(void)
 {
+	struct task_struct *task;
+
 	if (!xen_domain())
 		return -ENODEV;
 
@@ -724,7 +743,7 @@
 	register_sysctl_table(xen_root);
 #endif
 
-#ifdef CONFIG_XEN_PV
+#if defined(CONFIG_XEN_PV) && !defined(CONFIG_XEN_UNPOPULATED_ALLOC)
 	{
 		int i;
 
@@ -739,9 +758,50 @@
 	}
 #endif
 
+	task = kthread_run(balloon_thread, NULL, "xen-balloon");
+	if (IS_ERR(task)) {
+		pr_err("xen-balloon thread could not be started, ballooning will not work!\n");
+		return PTR_ERR(task);
+	}
+
 	/* Init the xen-balloon driver. */
 	xen_balloon_init();
 
 	return 0;
 }
 subsys_initcall(balloon_init);
+
+static int __init balloon_wait_finish(void)
+{
+	long credit, last_credit = 0;
+	unsigned long last_changed = 0;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	/* PV guests don't need to wait. */
+	if (xen_pv_domain() || !current_credit())
+		return 0;
+
+	pr_notice("Waiting for initial ballooning down having finished.\n");
+
+	while ((credit = current_credit()) < 0) {
+		if (credit != last_credit) {
+			last_changed = jiffies;
+			last_credit = credit;
+		}
+		if (balloon_state == BP_ECANCELED) {
+			pr_warn_once("Initial ballooning failed, %ld pages need to be freed.\n",
+				     -credit);
+			if (jiffies - last_changed >= HZ * balloon_boot_timeout)
+				panic("Initial ballooning failed!\n");
+		}
+
+		schedule_timeout_interruptible(HZ / 10);
+	}
+
+	pr_notice("Initial ballooning down finished.\n");
+
+	return 0;
+}
+late_initcall_sync(balloon_wait_finish);