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mm: shmem: avoid atomic operation during shmem_getpage_gfp 

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 <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2014-06-04 16:10:24 -07:00 committed by Linus Torvalds
parent b745bc85f2
commit 07a4278843
2 changed files with 2 additions and 1 deletions
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1
include/linux/page-flags.h
View File

@ -208,6 +208,7 @@ PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
PAGEFLAG(SavePinned, savepinned); /* Xen */ PAGEFLAG(SavePinned, savepinned); /* Xen */
PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked) PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
__SETPAGEFLAG(SwapBacked, swapbacked)
__PAGEFLAG(SlobFree, slob_free) __PAGEFLAG(SlobFree, slob_free)

2
mm/shmem.c
View File

@ -1132,7 +1132,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
goto decused; goto decused;
} }
SetPageSwapBacked(page); __SetPageSwapBacked(page);
__set_page_locked(page); __set_page_locked(page);
error = mem_cgroup_charge_file(page, current->mm, error = mem_cgroup_charge_file(page, current->mm,
gfp & GFP_RECLAIM_MASK); gfp & GFP_RECLAIM_MASK);