Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755538AbbB0WQ6 (ORCPT ); Fri, 27 Feb 2015 17:16:58 -0500 Received: from mail-ie0-f173.google.com ([209.85.223.173]:34826 "EHLO mail-ie0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754932AbbB0WQz (ORCPT ); Fri, 27 Feb 2015 17:16:55 -0500 Date: Fri, 27 Feb 2015 14:16:52 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Vlastimil Babka , Christoph Lameter , Pekka Enberg , Joonsoo Kim , Johannes Weiner , Mel Gorman , Pravin Shelar , Jarno Rajahalme , Li Zefan , Greg Thelen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, cgroups@vger.kernel.org, dev@openvswitch.org Subject: [patch v2 1/3] mm: remove GFP_THISNODE In-Reply-To: Message-ID: References: User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6987 Lines: 194 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 --- v2: fix typos in commit message per Vlastimil include/linux/gfp.h | 10 ---------- mm/page_alloc.c | 22 ++++++---------------- mm/slab.c | 22 ++++++++++++++++++---- net/openvswitch/flow.c | 4 +++- 4 files changed, 27 insertions(+), 31 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -117,16 +117,6 @@ struct vm_area_struct; __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN | \ __GFP_NO_KSWAPD) -/* - * GFP_THISNODE does not perform any reclaim, you most likely want to - * use __GFP_THISNODE to allocate from a given node without fallback! - */ -#ifdef CONFIG_NUMA -#define GFP_THISNODE (__GFP_THISNODE | __GFP_NOWARN | __GFP_NORETRY) -#else -#define GFP_THISNODE ((__force gfp_t)0) -#endif - /* This mask makes up all the page movable related flags */ #define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE) diff --git a/mm/page_alloc.c b/mm/page_alloc.c --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2355,13 +2355,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, /* The OOM killer does not compensate for light reclaim */ if (!(gfp_mask & __GFP_FS)) 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; } @@ -2615,15 +2609,11 @@ __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: @@ -2816,7 +2806,7 @@ __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; diff --git a/mm/slab.c b/mm/slab.c --- a/mm/slab.c +++ b/mm/slab.c @@ -857,6 +857,11 @@ static inline void *____cache_alloc_node(struct kmem_cache *cachep, return NULL; } +static inline gfp_t gfp_exact_node(gfp_t flags) +{ + return flags; +} + #else /* CONFIG_NUMA */ static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int); @@ -1023,6 +1028,15 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp) return __cache_free_alien(cachep, objp, node, page_node); } + +/* + * Construct gfp mask to allocate from a specific node but do not invoke reclaim + * or warn about failures. + */ +static inline gfp_t gfp_exact_node(gfp_t flags) +{ + return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~__GFP_WAIT; +} #endif /* @@ -2825,7 +2839,7 @@ alloc_done: if (unlikely(!ac->avail)) { int x; force_grow: - x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL); + x = cache_grow(cachep, gfp_exact_node(flags), node, NULL); /* cache_grow can reenable interrupts, then ac could change. */ ac = cpu_cache_get(cachep); @@ -3019,7 +3033,7 @@ retry: get_node(cache, nid) && get_node(cache, nid)->free_objects) { obj = ____cache_alloc_node(cache, - flags | GFP_THISNODE, nid); + gfp_exact_node(flags), nid); if (obj) break; } @@ -3047,7 +3061,7 @@ retry: nid = page_to_nid(page); if (cache_grow(cache, flags, nid, page)) { obj = ____cache_alloc_node(cache, - flags | GFP_THISNODE, nid); + gfp_exact_node(flags), nid); if (!obj) /* * Another processor may allocate the @@ -3118,7 +3132,7 @@ retry: must_grow: spin_unlock(&n->list_lock); - x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL); + x = cache_grow(cachep, gfp_exact_node(flags), nodeid, NULL); if (x) goto retry; diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c --- a/net/openvswitch/flow.c +++ b/net/openvswitch/flow.c @@ -100,7 +100,9 @@ void ovs_flow_stats_update(struct sw_flow *flow, __be16 tcp_flags, new_stats = kmem_cache_alloc_node(flow_stats_cache, - GFP_THISNODE | + GFP_NOWAIT | + __GFP_THISNODE | + __GFP_NOWARN | __GFP_NOMEMALLOC, node); if (likely(new_stats)) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/