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mm, sl[au]b: add __GFP_ATOMIC to the GFP reclaim mask
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Commit d0164ad ("mm, page_alloc: distinguish between being unable
to sleep, unwilling to sleep and avoiding waking kswapd") modified
__GFP_WAIT to explicitly identify the difference between atomic callers
and those that were unwilling to sleep.  Later the definition was
removed entirely.

The GFP_RECLAIM_MASK is the set of flags that affect watermark checking
and reclaim behaviour but __GFP_ATOMIC was never added.  Without it,
atomic users of the slab allocator strip the __GFP_ATOMIC flag and
cannot access the page allocator atomic reserves.  This patch addresses
the problem.

The user-visible impact depends on the workload but potentially atomic
allocations unnecessarily fail without this path.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Reported-by: Marcin Wojtas <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: <[email protected]>	[4.4+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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gormanm authored and torvalds committed Jun 25, 2016
1 parent 9b75a86 commit e838a45
Showing 1 changed file with 2 additions and 1 deletion.
3 changes: 2 additions & 1 deletion mm/internal.h
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,8 @@
*/
#define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\
__GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
__GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC)
__GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\
__GFP_ATOMIC)

/* The GFP flags allowed during early boot */
#define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS))
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