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author | David Rientjes <rientjes@google.com> | 2015-04-14 15:46:55 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-14 16:49:03 -0700 |
commit | 4167e9b2cf10f8a4bcda0c713ddc8bb0a18e8187 (patch) | |
tree | 744caf92870f2afa4facca7cdfbb6315e71b6592 /mm/page_alloc.c | |
parent | b360edb43f8ed50aa7b8c9aae7d7557a1a6e32c8 (diff) | |
download | linux-4167e9b2cf10f8a4bcda0c713ddc8bb0a18e8187.tar.gz |
mm: remove GFP_THISNODE
NOTE: this is not about __GFP_THISNODE, this is only about GFP_THISNODE. GFP_THISNODE is a secret combination of gfp bits that have different behavior than expected. It is a combination of __GFP_THISNODE, __GFP_NORETRY, and __GFP_NOWARN and is special-cased in the page allocator slowpath to fail without trying reclaim even though it may be used in combination with __GFP_WAIT. An example of the problem this creates: commit e97ca8e5b864 ("mm: fix GFP_THISNODE callers and clarify") fixed up many users of GFP_THISNODE that really just wanted __GFP_THISNODE. The problem doesn't end there, however, because even it was a no-op for alloc_misplaced_dst_page(), which also sets __GFP_NORETRY and __GFP_NOWARN, and migrate_misplaced_transhuge_page(), where __GFP_NORETRY and __GFP_NOWAIT is set in GFP_TRANSHUGE. Converting GFP_THISNODE to __GFP_THISNODE is a no-op in these cases since the page allocator special-cases __GFP_THISNODE && __GFP_NORETRY && __GFP_NOWARN. It's time to just remove GFP_THISNODE entirely. We leave __GFP_THISNODE to restrict an allocation to a local node, but remove GFP_THISNODE and its obscurity. Instead, we require that a caller clear __GFP_WAIT if it wants to avoid reclaim. This allows the aforementioned functions to actually reclaim as they should. It also enables any future callers that want to do __GFP_THISNODE but also __GFP_NORETRY && __GFP_NOWARN to reclaim. The rule is simple: if you don't want to reclaim, then don't set __GFP_WAIT. Aside: ovs_flow_stats_update() really wants to avoid reclaim as well, so it is unchanged. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Acked-by: Pekka Enberg <penberg@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Pravin Shelar <pshelar@nicira.com> Cc: Jarno Rajahalme <jrajahalme@nicira.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Greg Thelen <gthelen@google.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r-- | mm/page_alloc.c | 22 |
1 files changed, 6 insertions, 16 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 84466a4b1b36..86af1a96a6dc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2412,13 +2412,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, *did_some_progress = 1; goto out; } - /* - * GFP_THISNODE contains __GFP_NORETRY and we never hit this. - * Sanity check for bare calls of __GFP_THISNODE, not real OOM. - * The caller should handle page allocation failure by itself if - * it specifies __GFP_THISNODE. - * Note: Hugepage uses it but will hit PAGE_ALLOC_COSTLY_ORDER. - */ + /* The OOM killer may not free memory on a specific node */ if (gfp_mask & __GFP_THISNODE) goto out; } @@ -2673,15 +2667,11 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, } /* - * GFP_THISNODE (meaning __GFP_THISNODE, __GFP_NORETRY and - * __GFP_NOWARN set) should not cause reclaim since the subsystem - * (f.e. slab) using GFP_THISNODE may choose to trigger reclaim - * using a larger set of nodes after it has established that the - * allowed per node queues are empty and that nodes are - * over allocated. + * If this allocation cannot block and it is for a specific node, then + * fail early. There's no need to wakeup kswapd or retry for a + * speculative node-specific allocation. */ - if (IS_ENABLED(CONFIG_NUMA) && - (gfp_mask & GFP_THISNODE) == GFP_THISNODE) + if (IS_ENABLED(CONFIG_NUMA) && (gfp_mask & __GFP_THISNODE) && !wait) goto nopage; retry: @@ -2874,7 +2864,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, /* * Check the zones suitable for the gfp_mask contain at least one * valid zone. It's possible to have an empty zonelist as a result - * of GFP_THISNODE and a memoryless node + * of __GFP_THISNODE and a memoryless node */ if (unlikely(!zonelist->_zonerefs->zone)) return NULL; |