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SubjectRe: [patch 13/13] mm: memcontrol: rewrite uncharge API
On Fri, 20 Jun 2014 20:34:43 -0400 Sasha Levin <sasha.levin@oracle.com> wrote:

> I'm seeing the following when booting a VM, bisection pointed me to this
> patch.
>
> [ 32.830823] BUG: using __this_cpu_add() in preemptible [00000000] code: mkdir/8677

Thanks. This one was fixed earlier today.

From: Michal Hocko <mhocko@suse.cz>
Subject: memcg: mem_cgroup_charge_statistics needs preempt_disable

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@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/memcontrol.c | 3 +++
1 file changed, 3 insertions(+)

diff -puN mm/memcontrol.c~mm-memcontrol-rewrite-uncharge-api-fix-4 mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcontrol-rewrite-uncharge-api-fix-4
+++ a/mm/memcontrol.c
@@ -904,6 +904,8 @@ static void mem_cgroup_charge_statistics
struct page *page,
int nr_pages)
{
+ preempt_disable();
+
/*
* Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
* counted as CACHE even if it's on ANON LRU.
@@ -928,6 +930,7 @@ static void mem_cgroup_charge_statistics
}

__this_cpu_add(memcg->stat->nr_page_events, nr_pages);
+ preempt_enable();
}

unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list lru)
_


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