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@xxxxxxxxxx> --- include/linux/page-flags.h | 20 ++++++++++++++++++++ mm/memory-failure.c | 2 +- 2 files changed, 21 insertions(+), 1 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index e90a673..ca8b626 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -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 diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 56080ea..c22076f 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -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)) { -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>