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thp: allow a hwpoisoned head page to be put back to LRU 

Andrea Arcangeli pointed out to me that a check in __memory_failure()
which was intended to prevent THP tail pages from being checked for the
absence of the PG_lru flag (something that is always the case), was also
preventing THP head pages from being checked.

A THP head page could actually benefit from the call to shake_page() by
ending up being put back to a LRU, provided it had been waiting in a
pagevec array.

Andrea suggested that the "!PageTransCompound(p)" in the if-statement
should be replaced by a "!PageTransTail(p)", thus allowing THP head pages
to be checked and possibly shaken.

Signed-off-by: Dean Nelson <dnelson@redhat.com>
Cc: Jin Dongming <jin.dongming@np.css.fujitsu.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dean Nelson 2012-03-21 16:34:05 -07:00 committed by Linus Torvalds
parent 6d9d88d07e
commit 385de35722
2 changed files with 21 additions and 1 deletions
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20
include/linux/page-flags.h
View File

@ -414,11 +414,26 @@ static inline int PageTransHuge(struct page *page)
return PageHead(page);
}
/*
* PageTransCompound returns true for both transparent huge pages
* and hugetlbfs pages, so it should only be called when it's known
* that hugetlbfs pages aren't involved.
*/
static inline int PageTransCompound(struct page *page)
{
return PageCompound(page);
}
/*
* PageTransTail returns true for both transparent huge pages
* and hugetlbfs pages, so it should only be called when it's known
* that hugetlbfs pages aren't involved.
*/
static inline int PageTransTail(struct page *page)
{
return PageTail(page);
}
#else
static inline int PageTransHuge(struct page *page)
@ -430,6 +445,11 @@ static inline int PageTransCompound(struct page *page)
{
return 0;
}
static inline int PageTransTail(struct page *page)
{
return 0;
}
#endif
#ifdef CONFIG_MMU

2
mm/memory-failure.c
View File

@ -1063,7 +1063,7 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
* The check (unnecessarily) ignores LRU pages being isolated and
* walked by the page reclaim code, however that's not a big loss.
*/
if (!PageHuge(p) && !PageTransCompound(p)) {
if (!PageHuge(p) && !PageTransTail(p)) {
if (!PageLRU(p))
shake_page(p, 0);
if (!PageLRU(p)) {