Re: [PATCH -mm] memcg: mem_cgroup_charge_statistics needs preempt_disable

[Johannes Weiner]

On Fri, Jun 20, 2014 at 06:36:11PM +0200, Michal Hocko wrote:
> preempt_disable was previously disabled by lock_page_cgroup which has
> been removed by "mm: memcontrol: rewrite uncharge API".
> 
> This fixes the a flood of splats like this:
> [    3.149371] BUG: using __this_cpu_add() in preemptible [00000000] code: udevd/1271
> [    3.151458] caller is __this_cpu_preempt_check+0x13/0x15
> [    3.152927] CPU: 0 PID: 1271 Comm: udevd Not tainted 3.15.0-test1 #366
> [    3.154637] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> [    3.156788]  0000000000000000 ffff88000005fba8 ffffffff814efe3f 0000000000000000
> [    3.158810]  ffff88000005fbd8 ffffffff8125b969 ffff880007413448 0000000000000001
> [    3.160836]  ffffea00001e8c00 0000000000000001 ffff88000005fbe8 ffffffff8125b9a8
> [    3.162950] Call Trace:
> [    3.163598]  [<ffffffff814efe3f>] dump_stack+0x4e/0x7a
> [    3.164942]  [<ffffffff8125b969>] check_preemption_disabled+0xd2/0xe5
> [    3.166618]  [<ffffffff8125b9a8>] __this_cpu_preempt_check+0x13/0x15
> [    3.168267]  [<ffffffff8112b630>] mem_cgroup_charge_statistics.isra.36+0xb5/0xc6
> [    3.170169]  [<ffffffff8112d2c5>] commit_charge+0x23c/0x256
> [    3.171823]  [<ffffffff8113101b>] mem_cgroup_commit_charge+0xb8/0xd7
> [    3.173838]  [<ffffffff810f5dab>] shmem_getpage_gfp+0x399/0x605
> [    3.175363]  [<ffffffff810f7456>] shmem_write_begin+0x3d/0x58
> [    3.176854]  [<ffffffff810e1361>] generic_perform_write+0xbc/0x192
> [    3.178445]  [<ffffffff8114a086>] ? file_update_time+0x34/0xac
> [    3.179952]  [<ffffffff810e2ae4>] __generic_file_aio_write+0x2c0/0x300
> [    3.181655]  [<ffffffff810e2b76>] generic_file_aio_write+0x52/0xbd
> [    3.183234]  [<ffffffff81133944>] do_sync_write+0x59/0x78
> [    3.184630]  [<ffffffff81133ea8>] vfs_write+0xc4/0x181
> [    3.185957]  [<ffffffff81134801>] SyS_write+0x4a/0x91
> [    3.187258]  [<ffffffff814fd30e>] tracesys+0xd0/0xd5
> 
> Signed-off-by: Michal Hocko <mhocko@xxxxxxx>

Thanks, Michal.

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
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