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mm: memcontrol: rearrange charging fast path 

The charging path currently starts out with OOM condition checks when
OOM is the rarest possible case.

Rearrange this code to run OOM/task dying checks only after trying the
percpu charge and the res_counter charge and bail out before entering
reclaim.  Attempting a charge does not hurt an (oom-)killed task as much
as every charge attempt having to check OOM conditions.  Also, only
check __GFP_NOFAIL when the charge would actually fail.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Johannes Weiner 2014-08-06 16:05:44 -07:00 committed by Linus Torvalds
parent 6539cc0538
commit 06b078fc06
1 changed files with 17 additions and 16 deletions
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33
mm/memcontrol.c
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@ -2575,22 +2575,6 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
if (mem_cgroup_is_root(memcg))
goto done;
/*
* Unlike in global OOM situations, memcg is not in a physical
* memory shortage. Allow dying and OOM-killed tasks to
* bypass the last charges so that they can exit quickly and
* free their memory.
*/
if (unlikely(test_thread_flag(TIF_MEMDIE) ||
fatal_signal_pending(current) ||
current->flags & PF_EXITING))
goto bypass;
if (unlikely(task_in_memcg_oom(current)))
goto nomem;
if (gfp_mask & __GFP_NOFAIL)
oom = false;
retry:
if (consume_stock(memcg, nr_pages))
goto done;
@ -2612,6 +2596,20 @@ retry:
goto retry;
}
/*
* Unlike in global OOM situations, memcg is not in a physical
* memory shortage. Allow dying and OOM-killed tasks to
* bypass the last charges so that they can exit quickly and
* free their memory.
*/
if (unlikely(test_thread_flag(TIF_MEMDIE) ||
fatal_signal_pending(current) ||
current->flags & PF_EXITING))
goto bypass;
if (unlikely(task_in_memcg_oom(current)))
goto nomem;
if (!(gfp_mask & __GFP_WAIT))
goto nomem;
@ -2640,6 +2638,9 @@ retry:
if (mem_cgroup_wait_acct_move(mem_over_limit))
goto retry;
if (gfp_mask & __GFP_NOFAIL)
goto bypass;
if (fatal_signal_pending(current))
goto bypass;