Re: [patch] memcg: pin execution to current cpu while draining stock
From: KAMEZAWA Hiroyuki <hidden>
Date: 2011-08-18 00:31:44
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On Wed, 17 Aug 2011 21:49:27 +0200 Johannes Weiner [off-list ref] wrote:
Commit d1a05b6 'memcg: do not try to drain per-cpu caches without pages' added a drain_local_stock() call to a preemptible section. The draining task looks up the cpu-local stock twice to set the draining-flag, then to drain the stock and clear the flag again. If the task is migrated to a different CPU in between, noone will clear the flag on the first stock and it will be forever undrainable. Its charge can not be recovered and the cgroup can not be deleted anymore. Properly pin the task to the executing CPU while draining stocks. Signed-off-by: Johannes Weiner <redacted> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com Cc: Michal Hocko <redacted>
Thanks. I think Shaoha Li reported this. Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com == http://www.spinics.net/lists/linux-mm/msg22635.html I get below warning: BUG: using smp_processor_id() in preemptible [00000000] code: bash/739 caller is drain_local_stock+0x1a/0x55 Pid: 739, comm: bash Tainted: G W 3.0.0+ #255 Call Trace: [<ffffffff813435c6>] debug_smp_processor_id+0xc2/0xdc [<ffffffff8114ae9b>] drain_local_stock+0x1a/0x55 [<ffffffff8114b076>] drain_all_stock+0x98/0x13a [<ffffffff8114f04c>] mem_cgroup_force_empty+0xa3/0x27a [<ffffffff8114ff1d>] ? sys_close+0x38/0x138 [<ffffffff811a7631>] ? environ_read+0x1d/0x159 [<ffffffff8114f253>] mem_cgroup_force_empty_write+0x17/0x19 [<ffffffff810c72fb>] cgroup_file_write+0xa8/0xba [<ffffffff811522ce>] vfs_write+0xb3/0x138 [<ffffffff81152416>] sys_write+0x4a/0x71 [<ffffffff8114ffd5>] ? sys_close+0xf0/0x138 [<ffffffff8176deab>] system_call_fastpath+0x16/0x1b drain_local_stock() should be run with preempt disabled. == Andrew, could you pull this one , too ? http://www.spinics.net/lists/linux-mm/msg22636.html Thanks, -Kame
quoted hunk ↗ jump to hunk
--- mm/memcontrol.c | 9 ++------- 1 files changed, 2 insertions(+), 7 deletions(-)diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 697a1d5..e9b1206 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c@@ -2085,13 +2085,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync) /* Notify other cpus that system-wide "drain" is running */ get_online_cpus(); - /* - * Get a hint for avoiding draining charges on the current cpu, - * which must be exhausted by our charging. It is not required that - * this be a precise check, so we use raw_smp_processor_id() instead of - * getcpu()/putcpu(). - */ - curcpu = raw_smp_processor_id(); + curcpu = get_cpu(); for_each_online_cpu(cpu) { struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); struct mem_cgroup *mem;@@ -2108,6 +2102,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync) schedule_work_on(cpu, &stock->work); } } + put_cpu(); if (!sync) goto out;-- 1.7.6 -- 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/
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