There is a race between hwpoison page and unpoison page, memory_failure
set the page hwpoison and increase num_poisoned_pages without hold page
lock, and one page count will be accounted against thp for num_poisoned_pages.
However, unpoison can occur before memory_failure hold page lock and
split transparent hugepage, unpoison will decrease num_poisoned_pages
by 1 << compound_order since memory_failure has not yet split transparent
hugepage with page lock held. That means we account one page for hwpoison
and 1 << compound_order for unpoison. This patch fix it by decrease one
account for num_poisoned_pages against no hugetlbfs pages case.
Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5092e06..6bfd51e 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1350,7 +1350,7 @@ int unpoison_memory(unsigned long pfn)
return 0;
}
if (TestClearPageHWPoison(p))
- atomic_long_sub(nr_pages, &num_poisoned_pages);
+ atomic_long_dec(&num_poisoned_pages);
pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn);
return 0;
}
--
1.8.1.2
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