On Wed, 17 Aug 2011 21:49:27 +0200 Johannes Weiner <jweiner@xxxxxxxxxx> 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 <jweiner@xxxxxxxxxx> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx > Cc: Michal Hocko <mhocko@xxxxxxx> Thanks. I think Shaoha Li reported this. Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx == 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 > --- > 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@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>