[PATCH v3 13/15] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page

nao.horiguchi
2020-06-24T15:02:30Z

From: Oscar Salvador <osalvador@suse.de>

Merging soft_offline_huge_page and __soft_offline_page let us get rid of
quite some duplicated code, and makes the code much easier to follow.

Now, __soft_offline_page will handle both normal and hugetlb pages.

Note that move put_page() block to the beginning of page_handle_poison()
with drain_all_pages() in order to make sure that the target page is
freed and sent into free list to make take_page_off_buddy() work properly.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
ChangeLog v2 -> v3:
- use page_is_file_lru() instead of page_is_file_cache(),
- add description about put_page() and drain_all_pages().
- fix coding style warnings by checkpatch.pl
---
mm/memory-failure.c | 185 ++++++++++++++++++++------------------------
1 file changed, 86 insertions(+), 99 deletions(-)

diff --git v5.8-rc1-mmots-2020-06-20-21-44/mm/memory-failure.c v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/memory-failure.c
index f744eb90c15c..22c904f6d17a 100644
--- v5.8-rc1-mmots-2020-06-20-21-44/mm/memory-failure.c
+++ v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/memory-failure.c
@@ -78,14 +78,36 @@ EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
EXPORT_SYMBOL_GPL(hwpoison_filter_flags_value);

-static void page_handle_poison(struct page *page, bool release)
+static bool page_handle_poison(struct page *page, bool hugepage_or_freepage, bool release)
{
+ if (release) {
+ put_page(page);
+ drain_all_pages(page_zone(page));
+ }
+
+ if (hugepage_or_freepage) {
+ /*
+ * Doing this check for free pages is also fine since dissolve_free_huge_page
+ * returns 0 for non-hugetlb pages as well.
+ */
+ if (dissolve_free_huge_page(page) || !take_page_off_buddy(page))
+ /*
+ * The hugetlb page can end up being enqueued back into
+ * the freelists by means of:
+ * unmap_and_move_huge_page
+ * putback_active_hugepage
+ * put_page->free_huge_page
+ * enqueue_huge_page
+ * If this happens, we might lose the race against an allocation.
+ */
+ return false;
+ }

SetPageHWPoison(page);
- if (release)
- put_page(page);
page_ref_inc(page);
num_poisoned_pages_inc();
+
+ return true;
}

static int hwpoison_filter_dev(struct page *p)
@@ -1718,63 +1740,52 @@ static int get_any_page(struct page *page, unsigned long pfn)
return ret;
}

-static int soft_offline_huge_page(struct page *page)
+static bool isolate_page(struct page *page, struct list_head *pagelist)
{
- int ret;
- unsigned long pfn = page_to_pfn(page);
- struct page *hpage = compound_head(page);
- LIST_HEAD(pagelist);
+ bool isolated = false;
+ bool lru = PageLRU(page);
+
+ if (PageHuge(page)) {
+ isolated = isolate_huge_page(page, pagelist);
+ } else {
+ if (lru)
+ isolated = !isolate_lru_page(page);
+ else
+ isolated = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
+
+ if (isolated)
+ list_add(&page->lru, pagelist);

- /*
- * This double-check of PageHWPoison is to avoid the race with
- * memory_failure(). See also comment in __soft_offline_page().
- */
- lock_page(hpage);
- if (PageHWPoison(hpage)) {
- unlock_page(hpage);
- put_page(hpage);
- pr_info("soft offline: %#lx hugepage already poisoned\n", pfn);
- return -EBUSY;
}
- unlock_page(hpage);

- ret = isolate_huge_page(hpage, &pagelist);
+ if (isolated && lru)
+ inc_node_page_state(page, NR_ISOLATED_ANON +
+ page_is_file_lru(page));
+
/*
- * get_any_page() and isolate_huge_page() takes a refcount each,
- * so need to drop one here.
+ * If we succeed to isolate the page, we grabbed another refcount on
+ * the page, so we can safely drop the one we got from get_any_pages().
+ * If we failed to isolate the page, it means that we cannot go further
+ * and we will return an error, so drop the reference we got from
+ * get_any_pages() as well.
*/
- put_page(hpage);
- if (!ret) {
- pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn);
- return -EBUSY;
- }
-
- ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
- MIGRATE_SYNC, MR_MEMORY_FAILURE);
- if (ret) {
- pr_info("soft offline: %#lx: hugepage migration failed %d, type %lx (%pGp)\n",
- pfn, ret, page->flags, &page->flags);
- if (!list_empty(&pagelist))
- putback_movable_pages(&pagelist);
- if (ret > 0)
- ret = -EIO;
- } else {
- /*
- * We set PG_hwpoison only when we were able to take the page
- * off the buddy.
- */
- if (!dissolve_free_huge_page(page) && take_page_off_buddy(page))
- page_handle_poison(page, false);
- else
- ret = -EBUSY;
- }
- return ret;
+ put_page(page);
+ return isolated;
}

+/*
+ * __soft_offline_page handles hugetlb-pages and non-hugetlb pages.
+ * If the page is a non-dirty unmapped page-cache page, it simply invalidates.
+ * If the page is mapped, it migrates the contents over.
+ */
static int __soft_offline_page(struct page *page)
{
- int ret;
+ int ret = 0;
unsigned long pfn = page_to_pfn(page);
+ struct page *hpage = compound_head(page);
+ const char *msg_page[] = {"page", "hugepage"};
+ bool huge = PageHuge(page);
+ LIST_HEAD(pagelist);

/*
* Check PageHWPoison again inside page lock because PageHWPoison
@@ -1783,98 +1794,74 @@ static int __soft_offline_page(struct page *page)
* so there's no race between soft_offline_page() and memory_failure().
*/
lock_page(page);
- wait_on_page_writeback(page);
+ if (!PageHuge(page))
+ wait_on_page_writeback(page);
if (PageHWPoison(page)) {
unlock_page(page);
put_page(page);
pr_info("soft offline: %#lx page already poisoned\n", pfn);
return -EBUSY;
}
- /*
- * Try to invalidate first. This should work for
- * non dirty unmapped page cache pages.
- */
- ret = invalidate_inode_page(page);
+
+ if (!PageHuge(page))
+ /*
+ * Try to invalidate first. This should work for
+ * non dirty unmapped page cache pages.
+ */
+ ret = invalidate_inode_page(page);
unlock_page(page);
+
/*
* RED-PEN would be better to keep it isolated here, but we
* would need to fix isolation locking first.
*/
- if (ret == 1) {
+ if (ret) {
pr_info("soft_offline: %#lx: invalidated\n", pfn);
- page_handle_poison(page, true);
+ page_handle_poison(page, false, true);
return 0;
}

- /*
- * Simple invalidation didn't work.
- * Try to migrate to a new page instead. migrate.c
- * handles a large number of cases for us.
- */
- if (PageLRU(page))
- ret = isolate_lru_page(page);
- else
- ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
- /*
- * Drop page reference which is came from get_any_page()
- * successful isolate_lru_page() already took another one.
- */
- put_page(page);
- if (!ret) {
- LIST_HEAD(pagelist);
- /*
- * After isolated lru page, the PageLRU will be cleared,
- * so use !__PageMovable instead for LRU page's mapping
- * cannot have PAGE_MAPPING_MOVABLE.
- */
- if (!__PageMovable(page))
- inc_node_page_state(page, NR_ISOLATED_ANON +
- page_is_file_lru(page));
- list_add(&page->lru, &pagelist);
+ if (isolate_page(hpage, &pagelist)) {
ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
MIGRATE_SYNC, MR_MEMORY_FAILURE);
if (!ret) {
- page_handle_poison(page, true);
+ bool release = !huge;
+
+ if (!page_handle_poison(page, true, release))
+ ret = -EBUSY;
} else {
if (!list_empty(&pagelist))
putback_movable_pages(&pagelist);

- pr_info("soft offline: %#lx: migration failed %d, type %lx (%pGp)\n",
- pfn, ret, page->flags, &page->flags);
+
+ pr_info("soft offline: %#lx: %s migration failed %d, type %lx (%pGp)\n",
+ pfn, msg_page[huge], ret, page->flags, &page->flags);
if (ret > 0)
ret = -EIO;
}
} else {
- pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx (%pGp)\n",
- pfn, ret, page_count(page), page->flags, &page->flags);
+ pr_info("soft offline: %#lx: %s isolation failed: %d, page count %d, type %lx (%pGp)\n",
+ pfn, msg_page[huge], ret, page_count(page), page->flags, &page->flags);
}
return ret;
}

static int soft_offline_in_use_page(struct page *page)
{
- int ret;
struct page *hpage = compound_head(page);

if (!PageHuge(page) && PageTransHuge(hpage))
if (try_to_split_thp_page(page, "soft offline") < 0)
return -EBUSY;
-
- if (PageHuge(page))
- ret = soft_offline_huge_page(page);
- else
- ret = __soft_offline_page(page);
- return ret;
+ return __soft_offline_page(page);
}

static int soft_offline_free_page(struct page *page)
{
- int rc = -EBUSY;
+ int rc = 0;

- if (!dissolve_free_huge_page(page) && take_page_off_buddy(page)) {
- page_handle_poison(page, false);
- rc = 0;
- }
+ if (!page_handle_poison(page, true, false))
+ rc = -EBUSY;

return rc;
}
--
2.17.1