From 7951a52ed35d162063fa08b27894e302fd716ccd Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 24 Jun 2015 16:57:19 -0700 Subject: mm: oom_kill: simplify OOM killer locking The zonelist locking and the oom_sem are two overlapping locks that are used to serialize global OOM killing against different things. The historical zonelist locking serializes OOM kills from allocations with overlapping zonelists against each other to prevent killing more tasks than necessary in the same memory domain. Only when neither tasklists nor zonelists from two concurrent OOM kills overlap (tasks in separate memcgs bound to separate nodes) are OOM kills allowed to execute in parallel. The younger oom_sem is a read-write lock to serialize OOM killing against the PM code trying to disable the OOM killer altogether. However, the OOM killer is a fairly cold error path, there is really no reason to optimize for highly performant and concurrent OOM kills. And the oom_sem is just flat-out redundant. Replace both locking schemes with a single global mutex serializing OOM kills regardless of context. Change-Id: Ieb0b621bc3a391cc0a826a3ae53bf28ea4a8dbe5 Signed-off-by: Johannes Weiner Acked-by: Michal Hocko Acked-by: David Rientjes Cc: Tetsuo Handa Cc: Andrea Arcangeli Cc: Dave Chinner Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/oom.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/oom.h b/include/linux/oom.h index ea4b1b64e..acabe09da 100644 --- a/include/linux/oom.h +++ b/include/linux/oom.h @@ -32,6 +32,8 @@ enum oom_scan_t { /* Thread is the potential origin of an oom condition; kill first on oom */ #define OOM_FLAG_ORIGIN ((__force oom_flags_t)0x1) +extern struct mutex oom_lock; + static inline void set_current_oom_origin(void) { current->signal->oom_flags |= OOM_FLAG_ORIGIN; @@ -60,9 +62,6 @@ 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 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); -- cgit v1.2.3