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Subject[PATCH v1] mm, hwpoison: enable error handling on shmem thp
Date
From: Naoya Horiguchi <naoya.horiguchi@nec.com>

Currently hwpoison code checks PageAnon() for thp and refuses to handle
errors on non-anonymous thps (just for historical reason). We now
support non-anonymou thp like shmem one, so this patch suggests to enable
to handle shmem thps. Fortunately, we already have can_split_huge_page()
to check if a give thp is splittable, so this patch relies on it.

Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/memory-failure.c | 34 +++++++++-------------------------
1 file changed, 9 insertions(+), 25 deletions(-)

diff --git v5.11-rc6/mm/memory-failure.c v5.11-rc6_patched/mm/memory-failure.c
index e9481632fcd1..8c1575de0507 100644
--- v5.11-rc6/mm/memory-failure.c
+++ v5.11-rc6_patched/mm/memory-failure.c
@@ -956,20 +956,6 @@ static int __get_hwpoison_page(struct page *page)
{
struct page *head = compound_head(page);

- if (!PageHuge(head) && PageTransHuge(head)) {
- /*
- * Non anonymous thp exists only in allocation/free time. We
- * can't handle such a case correctly, so let's give it up.
- * This should be better than triggering BUG_ON when kernel
- * tries to touch the "partially handled" page.
- */
- if (!PageAnon(head)) {
- pr_err("Memory failure: %#lx: non anonymous thp\n",
- page_to_pfn(page));
- return 0;
- }
- }
-
if (get_page_unless_zero(head)) {
if (head == compound_head(page))
return 1;
@@ -1197,21 +1183,19 @@ static int identify_page_state(unsigned long pfn, struct page *p,

static int try_to_split_thp_page(struct page *page, const char *msg)
{
- lock_page(page);
- if (!PageAnon(page) || unlikely(split_huge_page(page))) {
- unsigned long pfn = page_to_pfn(page);
+ struct page *head;

+ lock_page(page);
+ head = compound_head(page);
+ if (PageTransHuge(head) && can_split_huge_page(head, NULL) &&
+ !split_huge_page(page)) {
unlock_page(page);
- if (!PageAnon(page))
- pr_info("%s: %#lx: non anonymous thp\n", msg, pfn);
- else
- pr_info("%s: %#lx: thp split failed\n", msg, pfn);
- put_page(page);
- return -EBUSY;
+ return 0;
}
+ pr_info("%s: %#lx: thp split failed\n", msg, page_to_pfn(page));
unlock_page(page);
-
- return 0;
+ put_page(page);
+ return -EBUSY;
}

static int memory_failure_hugetlb(unsigned long pfn, int flags)
--
2.25.1
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