From: zhongjiang <zhongjiang@xxxxxxxxxx>
Subject: mm: hwpoison: fix thp split handing in soft_offline_in_use_page()
When soft_offline_in_use_page() runs on a thp tail page after pmd is
split, we trigger the following VM_BUG_ON_PAGE():
Memory failure: 0x3755ff: non anonymous thp
__get_any_page: 0x3755ff: unknown zero refcount page type 2fffff80000000
Soft offlining pfn 0x34d805 at process virtual address 0x20fff000
page:ffffea000d360140 count:0 mapcount:0 mapping:0000000000000000 index:0x1
flags: 0x2fffff80000000()
raw: 002fffff80000000 ffffea000d360108 ffffea000d360188 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0)
------------[ cut here ]------------
kernel BUG at ./include/linux/mm.h:519!
soft_offline_in_use_page() passed refcount and page lock from tail page to
head page, which is not needed because we can pass any subpage to
split_huge_page().
Naoya had fixed a similar issue in c3901e722b29 ("mm: hwpoison: fix thp
split handling in memory_failure()"). But he missed fixing soft offline.
Link: http://lkml.kernel.org/r/1551452476-24000-1-git-send-email-zhongjiang@xxxxxxxxxx
Fixes: 61f5d698cc97 ("mm: re-enable THP")
Signed-off-by: zhongjiang <zhongjiang@xxxxxxxxxx>
Acked-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.5+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
--- a/mm/memory-failure.c~mm-hwpoison-fix-thp-split-handing-in-soft_offline_in_use_page
+++ a/mm/memory-failure.c
@@ -1825,19 +1825,17 @@ static int soft_offline_in_use_page(stru
struct page *hpage = compound_head(page);
if (!PageHuge(page) && PageTransHuge(hpage)) {
- lock_page(hpage);
- if (!PageAnon(hpage) || unlikely(split_huge_page(hpage))) {
- unlock_page(hpage);
- if (!PageAnon(hpage))
+ lock_page(page);
+ if (!PageAnon(page) || unlikely(split_huge_page(page))) {
+ unlock_page(page);
+ if (!PageAnon(page))
pr_info("soft offline: %#lx: non anonymous thp\n", page_to_pfn(page));
else
pr_info("soft offline: %#lx: thp split failed\n", page_to_pfn(page));
- put_hwpoison_page(hpage);
+ put_hwpoison_page(page);
return -EBUSY;
}
- unlock_page(hpage);
- get_hwpoison_page(page);
- put_hwpoison_page(hpage);
+ unlock_page(page);
}
/*
_
