Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index ef858d5..26de020 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* mm/balloon_compaction.c
*
@@ -10,101 +11,183 @@
#include <linux/export.h>
#include <linux/balloon_compaction.h>
+static void balloon_page_enqueue_one(struct balloon_dev_info *b_dev_info,
+ struct page *page)
+{
+ /*
+ * Block others from accessing the 'page' when we get around to
+ * establishing additional references. We should be the only one
+ * holding a reference to the 'page' at this point. If we are not, then
+ * memory corruption is possible and we should stop execution.
+ */
+ BUG_ON(!trylock_page(page));
+ balloon_page_insert(b_dev_info, page);
+ unlock_page(page);
+ __count_vm_event(BALLOON_INFLATE);
+}
+
+/**
+ * balloon_page_list_enqueue() - inserts a list of pages into the balloon page
+ * list.
+ * @b_dev_info: balloon device descriptor where we will insert a new page to
+ * @pages: pages to enqueue - allocated using balloon_page_alloc.
+ *
+ * Driver must call this function to properly enqueue balloon pages before
+ * definitively removing them from the guest system.
+ *
+ * Return: number of pages that were enqueued.
+ */
+size_t balloon_page_list_enqueue(struct balloon_dev_info *b_dev_info,
+ struct list_head *pages)
+{
+ struct page *page, *tmp;
+ unsigned long flags;
+ size_t n_pages = 0;
+
+ spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+ list_for_each_entry_safe(page, tmp, pages, lru) {
+ list_del(&page->lru);
+ balloon_page_enqueue_one(b_dev_info, page);
+ n_pages++;
+ }
+ spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+ return n_pages;
+}
+EXPORT_SYMBOL_GPL(balloon_page_list_enqueue);
+
+/**
+ * balloon_page_list_dequeue() - removes pages from balloon's page list and
+ * returns a list of the pages.
+ * @b_dev_info: balloon device decriptor where we will grab a page from.
+ * @pages: pointer to the list of pages that would be returned to the caller.
+ * @n_req_pages: number of requested pages.
+ *
+ * Driver must call this function to properly de-allocate a previous enlisted
+ * balloon pages before definitively releasing it back to the guest system.
+ * This function tries to remove @n_req_pages from the ballooned pages and
+ * return them to the caller in the @pages list.
+ *
+ * Note that this function may fail to dequeue some pages even if the balloon
+ * isn't empty - since the page list can be temporarily empty due to compaction
+ * of isolated pages.
+ *
+ * Return: number of pages that were added to the @pages list.
+ */
+size_t balloon_page_list_dequeue(struct balloon_dev_info *b_dev_info,
+ struct list_head *pages, size_t n_req_pages)
+{
+ struct page *page, *tmp;
+ unsigned long flags;
+ size_t n_pages = 0;
+
+ spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+ list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) {
+ if (n_pages == n_req_pages)
+ break;
+
+ /*
+ * Block others from accessing the 'page' while we get around to
+ * establishing additional references and preparing the 'page'
+ * to be released by the balloon driver.
+ */
+ if (!trylock_page(page))
+ continue;
+
+ if (IS_ENABLED(CONFIG_BALLOON_COMPACTION) &&
+ PageIsolated(page)) {
+ /* raced with isolation */
+ unlock_page(page);
+ continue;
+ }
+ balloon_page_delete(page);
+ __count_vm_event(BALLOON_DEFLATE);
+ list_add(&page->lru, pages);
+ unlock_page(page);
+ n_pages++;
+ }
+ spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+
+ return n_pages;
+}
+EXPORT_SYMBOL_GPL(balloon_page_list_dequeue);
+
/*
* balloon_page_alloc - allocates a new page for insertion into the balloon
- * page list.
+ * page list.
*
- * Driver must call it to properly allocate a new enlisted balloon page.
- * Driver must call balloon_page_enqueue before definitively removing it from
- * the guest system. This function returns the page address for the recently
- * allocated page or NULL in the case we fail to allocate a new page this turn.
+ * Driver must call this function to properly allocate a new balloon page.
+ * Driver must call balloon_page_enqueue before definitively removing the page
+ * from the guest system.
+ *
+ * Return: struct page for the allocated page or NULL on allocation failure.
*/
struct page *balloon_page_alloc(void)
{
struct page *page = alloc_page(balloon_mapping_gfp_mask() |
- __GFP_NOMEMALLOC | __GFP_NORETRY);
+ __GFP_NOMEMALLOC | __GFP_NORETRY |
+ __GFP_NOWARN);
return page;
}
EXPORT_SYMBOL_GPL(balloon_page_alloc);
/*
- * balloon_page_enqueue - allocates a new page and inserts it into the balloon
- * page list.
- * @b_dev_info: balloon device descriptor where we will insert a new page to
+ * balloon_page_enqueue - inserts a new page into the balloon page list.
+ *
+ * @b_dev_info: balloon device descriptor where we will insert a new page
* @page: new page to enqueue - allocated using balloon_page_alloc.
*
- * Driver must call it to properly enqueue a new allocated balloon page
- * before definitively removing it from the guest system.
- * This function returns the page address for the recently enqueued page or
- * NULL in the case we fail to allocate a new page this turn.
+ * Drivers must call this function to properly enqueue a new allocated balloon
+ * page before definitively removing the page from the guest system.
+ *
+ * Drivers must not call balloon_page_enqueue on pages that have been pushed to
+ * a list with balloon_page_push before removing them with balloon_page_pop. To
+ * enqueue a list of pages, use balloon_page_list_enqueue instead.
*/
void balloon_page_enqueue(struct balloon_dev_info *b_dev_info,
struct page *page)
{
unsigned long flags;
- /*
- * Block others from accessing the 'page' when we get around to
- * establishing additional references. We should be the only one
- * holding a reference to the 'page' at this point.
- */
- BUG_ON(!trylock_page(page));
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
- balloon_page_insert(b_dev_info, page);
- __count_vm_event(BALLOON_INFLATE);
+ balloon_page_enqueue_one(b_dev_info, page);
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
- unlock_page(page);
}
EXPORT_SYMBOL_GPL(balloon_page_enqueue);
/*
* balloon_page_dequeue - removes a page from balloon's page list and returns
- * the its address to allow the driver release the page.
+ * its address to allow the driver to release the page.
* @b_dev_info: balloon device decriptor where we will grab a page from.
*
- * Driver must call it to properly de-allocate a previous enlisted balloon page
- * before definetively releasing it back to the guest system.
- * This function returns the page address for the recently dequeued page or
- * NULL in the case we find balloon's page list temporarily empty due to
- * compaction isolated pages.
+ * Driver must call this function to properly dequeue a previously enqueued page
+ * before definitively releasing it back to the guest system.
+ *
+ * Caller must perform its own accounting to ensure that this
+ * function is called only if some pages are actually enqueued.
+ *
+ * Note that this function may fail to dequeue some pages even if there are
+ * some enqueued pages - since the page list can be temporarily empty due to
+ * the compaction of isolated pages.
+ *
+ * TODO: remove the caller accounting requirements, and allow caller to wait
+ * until all pages can be dequeued.
+ *
+ * Return: struct page for the dequeued page, or NULL if no page was dequeued.
*/
struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
{
- struct page *page, *tmp;
unsigned long flags;
- bool dequeued_page;
+ LIST_HEAD(pages);
+ int n_pages;
- dequeued_page = false;
- spin_lock_irqsave(&b_dev_info->pages_lock, flags);
- list_for_each_entry_safe(page, tmp, &b_dev_info->pages, lru) {
- /*
- * Block others from accessing the 'page' while we get around
- * establishing additional references and preparing the 'page'
- * to be released by the balloon driver.
- */
- if (trylock_page(page)) {
-#ifdef CONFIG_BALLOON_COMPACTION
- if (PageIsolated(page)) {
- /* raced with isolation */
- unlock_page(page);
- continue;
- }
-#endif
- balloon_page_delete(page);
- __count_vm_event(BALLOON_DEFLATE);
- unlock_page(page);
- dequeued_page = true;
- break;
- }
- }
- spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+ n_pages = balloon_page_list_dequeue(b_dev_info, &pages, 1);
- if (!dequeued_page) {
+ if (n_pages != 1) {
/*
* If we are unable to dequeue a balloon page because the page
- * list is empty and there is no isolated pages, then something
+ * list is empty and there are no isolated pages, then something
* went out of track and some balloon pages are lost.
- * BUG() here, otherwise the balloon driver may get stuck into
+ * BUG() here, otherwise the balloon driver may get stuck in
* an infinite loop while attempting to release all its pages.
*/
spin_lock_irqsave(&b_dev_info->pages_lock, flags);
@@ -112,9 +195,9 @@
!b_dev_info->isolated_pages))
BUG();
spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
- page = NULL;
+ return NULL;
}
- return page;
+ return list_first_entry(&pages, struct page, lru);
}
EXPORT_SYMBOL_GPL(balloon_page_dequeue);
@@ -155,8 +238,8 @@
/*
* We can not easily support the no copy case here so ignore it as it
- * is unlikely to be use with ballon pages. See include/linux/hmm.h for
- * user of the MIGRATE_SYNC_NO_COPY mode.
+ * is unlikely to be used with balloon pages. See include/linux/hmm.h
+ * for a user of the MIGRATE_SYNC_NO_COPY mode.
*/
if (mode == MIGRATE_SYNC_NO_COPY)
return -EINVAL;