From 6d3e133532cd49fa925fe5c2a949c5900afd601c Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Thu, 28 Aug 2014 19:35:28 +0100 Subject: [PATCH] mm: shmem: avoid atomic operation during shmem_getpage_gfp commit 07a427884348d38a6fd56fa4d78249c407196650 upstream. shmem_getpage_gfp uses an atomic operation to set the SwapBacked field before it's even added to the LRU or visible. This is unnecessary as what could it possible race against? Use an unlocked variant. Signed-off-by: Mel Gorman Acked-by: Johannes Weiner Acked-by: Rik van Riel Cc: Vlastimil Babka Cc: Jan Kara Cc: Michal Hocko Cc: Hugh Dickins Cc: Dave Hansen Cc: Theodore Ts'o Cc: "Paul E. McKenney" Cc: Oleg Nesterov Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Mel Gorman Signed-off-by: Jiri Slaby --- include/linux/page-flags.h | 1 + mm/shmem.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 67fc8a2..0d1b035 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -208,6 +208,7 @@ PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */ PAGEFLAG(SavePinned, savepinned); /* Xen */ PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked) + __SETPAGEFLAG(SwapBacked, swapbacked) __PAGEFLAG(SlobFree, slob_free) diff --git a/mm/shmem.c b/mm/shmem.c index 15e5527..8572e8e 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1142,7 +1142,7 @@ repeat: goto decused; } - SetPageSwapBacked(page); + __SetPageSwapBacked(page); __set_page_locked(page); error = mem_cgroup_cache_charge(page, current->mm, gfp & GFP_RECLAIM_MASK); -- 1.9.1