On Mon 01-08-11 14:41:18, Shaohua Li wrote:
> 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.
Ahh, yes. This got in with d1a05b69 (memcg: do not try to drain per-cpu
caches without pages) which started calling drain_local_stock directly
rather than from a kernel thread.
> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Thanks for catching this.
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 5f84d23..11d5671 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2169,13 +2169,7 @@ 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;
> @@ -2192,6 +2186,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync)
> schedule_work_on(cpu, &stock->work);
> }
> }
> + put_cpu();
>
> if (!sync)
> goto out;
>
>
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--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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