diff options
authorDavid Rientjes <rientjes@google.com>2014-07-30 16:08:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-07-30 17:16:13 -0700
commitb104a35d32025ca740539db2808aa3385d0f30eb (patch)
parentf6789593d5cea42a4ecb1cbeab6a23ade5ebbba7 (diff)
mm, thp: do not allow thp faults to avoid cpuset restrictions
The page allocator relies on __GFP_WAIT to determine if ALLOC_CPUSET should be set in allocflags. ALLOC_CPUSET controls if a page allocation should be restricted only to the set of allowed cpuset mems. Transparent hugepages clears __GFP_WAIT when defrag is disabled to prevent the fault path from using memory compaction or direct reclaim. Thus, it is unfairly able to allocate outside of its cpuset mems restriction as a side-effect. This patch ensures that ALLOC_CPUSET is only cleared when the gfp mask is truly GFP_ATOMIC by verifying it is also not a thp allocation. Signed-off-by: David Rientjes <rientjes@google.com> Reported-by: Alex Thorlton <athorlton@sgi.com> Tested-by: Alex Thorlton <athorlton@sgi.com> Cc: Bob Liu <lliubbo@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hedi Berriche <hedi@sgi.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 8 insertions, 8 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8bcfe3ae20cb..ef44ad736ca1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2447,7 +2447,7 @@ static inline int
gfp_to_alloc_flags(gfp_t gfp_mask)
int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
- const gfp_t wait = gfp_mask & __GFP_WAIT;
+ const bool atomic = !(gfp_mask & (__GFP_WAIT | __GFP_NO_KSWAPD));
/* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */
BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
@@ -2456,20 +2456,20 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
* The caller may dip into page reserves a bit more if the caller
* cannot run direct reclaim, or if the caller has realtime scheduling
* policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will
- * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
+ * set both ALLOC_HARDER (atomic == true) and ALLOC_HIGH (__GFP_HIGH).
alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH);
- if (!wait) {
+ if (atomic) {
- * Not worth trying to allocate harder for
- * __GFP_NOMEMALLOC even if it can't schedule.
+ * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
+ * if it can't schedule.
- if (!(gfp_mask & __GFP_NOMEMALLOC))
+ if (!(gfp_mask & __GFP_NOMEMALLOC))
alloc_flags |= ALLOC_HARDER;
- * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
- * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+ * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the
+ * comment for __cpuset_node_allowed_softwall().
alloc_flags &= ~ALLOC_CPUSET;
} else if (unlikely(rt_task(current)) && !in_interrupt())