From e972a070e2d3296cd2e2cc2fd0561ce89a1d5ebf Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Wed, 6 Aug 2014 16:07:52 -0700 Subject: [PATCH] mm, oom: rename zonelist locking functions try_set_zonelist_oom() and clear_zonelist_oom() are not named properly to imply that they require locking semantics to avoid out_of_memory() being reordered. zone_scan_lock is required for both functions to ensure that there is proper locking synchronization. Rename try_set_zonelist_oom() to oom_zonelist_trylock() and rename clear_zonelist_oom() to oom_zonelist_unlock() to imply there is proper locking semantics. At the same time, convert oom_zonelist_trylock() to return bool instead of int since only success and failure are tested. Signed-off-by: David Rientjes Cc: "Kirill A. Shutemov" Cc: Johannes Weiner Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/oom.h | 4 ++-- mm/oom_kill.c | 30 +++++++++++++----------------- mm/page_alloc.c | 6 +++--- 3 files changed, 18 insertions(+), 22 deletions(-) diff --git a/include/linux/oom.h b/include/linux/oom.h index 4cd62677feb9..647395a1a550 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -55,8 +55,8 @@ extern void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, struct mem_cgroup *memcg, nodemask_t *nodemask, const char *message); -extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags); -extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags); +extern bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_flags); +extern void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_flags); extern void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask, int order, const nodemask_t *nodemask); diff --git a/mm/oom_kill.c b/mm/oom_kill.c index b0a1e1ff0353..d33aca1552ad 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -559,28 +559,25 @@ EXPORT_SYMBOL_GPL(unregister_oom_notifier); * if a parallel OOM killing is already taking place that includes a zone in * the zonelist. Otherwise, locks all zones in the zonelist and returns 1. */ -int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) +bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_mask) { struct zoneref *z; struct zone *zone; - int ret = 1; + bool ret = true; spin_lock(&zone_scan_lock); - for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { + for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) if (zone_is_oom_locked(zone)) { - ret = 0; + ret = false; goto out; } - } - for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { - /* - * Lock each zone in the zonelist under zone_scan_lock so a - * parallel invocation of try_set_zonelist_oom() doesn't succeed - * when it shouldn't. - */ + /* + * Lock each zone in the zonelist under zone_scan_lock so a parallel + * call to oom_zonelist_trylock() doesn't succeed when it shouldn't. + */ + for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) zone_set_flag(zone, ZONE_OOM_LOCKED); - } out: spin_unlock(&zone_scan_lock); @@ -592,15 +589,14 @@ out: * allocation attempts with zonelists containing them may now recall the OOM * killer, if necessary. */ -void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) +void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_mask) { struct zoneref *z; struct zone *zone; spin_lock(&zone_scan_lock); - for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) { + for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) zone_clear_flag(zone, ZONE_OOM_LOCKED); - } spin_unlock(&zone_scan_lock); } @@ -695,8 +691,8 @@ void pagefault_out_of_memory(void) return; zonelist = node_zonelist(first_memory_node, GFP_KERNEL); - if (try_set_zonelist_oom(zonelist, GFP_KERNEL)) { + if (oom_zonelist_trylock(zonelist, GFP_KERNEL)) { out_of_memory(NULL, 0, 0, NULL, false); - clear_zonelist_oom(zonelist, GFP_KERNEL); + oom_zonelist_unlock(zonelist, GFP_KERNEL); } } diff --git a/mm/page_alloc.c b/mm/page_alloc.c index fb9908148474..578236089ec1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2246,8 +2246,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, { struct page *page; - /* Acquire the OOM killer lock for the zones in zonelist */ - if (!try_set_zonelist_oom(zonelist, gfp_mask)) { + /* Acquire the per-zone oom lock for each zone */ + if (!oom_zonelist_trylock(zonelist, gfp_mask)) { schedule_timeout_uninterruptible(1); return NULL; } @@ -2285,7 +2285,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, out_of_memory(zonelist, gfp_mask, order, nodemask, false); out: - clear_zonelist_oom(zonelist, gfp_mask); + oom_zonelist_unlock(zonelist, gfp_mask); return page; }