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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 16c3150f-5858-4d0b-f633-08d6f5c5f9e1 X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Jun 2019 21:26:37.3529 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: guro@fb.com X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR15MB2595 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-20_14:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906200152 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jun 20, 2019 at 08:48:00AM -0700, Shakeel Butt wrote: > On Wed, Jun 19, 2019 at 6:57 PM Roman Gushchin wrote: > > > > As a result of reparenting a kmem_cache might belong to the root > > memory cgroup. It happens when a top-level memory cgroup is removed, > > and all associated kmem_caches are reparented to the root memory > > cgroup. > > > > The root memory cgroup is special, and requires a special handling. > > Let's make sure that we don't try to charge or uncharge it, > > and we handle system-wide vmstats exactly as for root kmem_caches. > > > > Note, that we still need to alter the kmem_cache reference counter, > > so that the kmem_cache can be released properly. > > > > The issue was discovered by running CRIU tests; the following warning > > did appear: > > > > [ 381.345960] WARNING: CPU: 0 PID: 11655 at mm/page_counter.c:62 > > page_counter_cancel+0x26/0x30 > > [ 381.345992] Modules linked in: > > [ 381.345998] CPU: 0 PID: 11655 Comm: kworker/0:8 Not tainted > > 5.2.0-rc5-next-20190618+ #1 > > [ 381.346001] Hardware name: Google Google Compute Engine/Google > > Compute Engine, BIOS Google 01/01/2011 > > [ 381.346010] Workqueue: memcg_kmem_cache kmemcg_workfn > > [ 381.346013] RIP: 0010:page_counter_cancel+0x26/0x30 > > [ 381.346017] Code: 1f 44 00 00 0f 1f 44 00 00 48 89 f0 53 48 f7 d8 > > f0 48 0f c1 07 48 29 f0 48 89 c3 48 89 c6 e8 61 ff ff ff 48 85 db 78 > > 02 5b c3 <0f> 0b 5b c3 66 0f 1f 44 00 00 0f 1f 44 00 00 48 85 ff 74 41 > > 41 55 > > [ 381.346019] RSP: 0018:ffffb3b34319f990 EFLAGS: 00010086 > > [ 381.346022] RAX: fffffffffffffffc RBX: fffffffffffffffc RCX: 0000000= 000000004 > > [ 381.346024] RDX: 0000000000000000 RSI: fffffffffffffffc RDI: ffff9c2= cd7165270 > > [ 381.346026] RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000= 000000001 > > [ 381.346028] R10: 00000000000000c8 R11: ffff9c2cd684e660 R12: 0000000= 0fffffffc > > [ 381.346030] R13: 0000000000000002 R14: 0000000000000006 R15: ffff9c2= c8ce1f200 > > [ 381.346033] FS: 0000000000000000(0000) GS:ffff9c2cd8200000(0000) > > knlGS:0000000000000000 > > [ 381.346039] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 381.346041] CR2: 00000000007be000 CR3: 00000001cdbfc005 CR4: 0000000= 0001606f0 > > [ 381.346043] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000= 000000000 > > [ 381.346045] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000= 000000400 > > [ 381.346047] Call Trace: > > [ 381.346054] page_counter_uncharge+0x1d/0x30 > > [ 381.346065] __memcg_kmem_uncharge_memcg+0x39/0x60 > > [ 381.346071] __free_slab+0x34c/0x460 > > [ 381.346079] deactivate_slab.isra.80+0x57d/0x6d0 > > [ 381.346088] ? add_lock_to_list.isra.36+0x9c/0xf0 > > [ 381.346095] ? __lock_acquire+0x252/0x1410 > > [ 381.346106] ? cpumask_next_and+0x19/0x20 > > [ 381.346110] ? slub_cpu_dead+0xd0/0xd0 > > [ 381.346113] flush_cpu_slab+0x36/0x50 > > [ 381.346117] ? slub_cpu_dead+0xd0/0xd0 > > [ 381.346125] on_each_cpu_mask+0x51/0x70 > > [ 381.346131] ? ksm_migrate_page+0x60/0x60 > > [ 381.346134] on_each_cpu_cond_mask+0xab/0x100 > > [ 381.346143] __kmem_cache_shrink+0x56/0x320 > > [ 381.346150] ? ret_from_fork+0x3a/0x50 > > [ 381.346157] ? unwind_next_frame+0x73/0x480 > > [ 381.346176] ? __lock_acquire+0x252/0x1410 > > [ 381.346188] ? kmemcg_workfn+0x21/0x50 > > [ 381.346196] ? __mutex_lock+0x99/0x920 > > [ 381.346199] ? kmemcg_workfn+0x21/0x50 > > [ 381.346205] ? kmemcg_workfn+0x21/0x50 > > [ 381.346216] __kmemcg_cache_deactivate_after_rcu+0xe/0x40 > > [ 381.346220] kmemcg_cache_deactivate_after_rcu+0xe/0x20 > > [ 381.346223] kmemcg_workfn+0x31/0x50 > > [ 381.346230] process_one_work+0x23c/0x5e0 > > [ 381.346241] worker_thread+0x3c/0x390 > > [ 381.346248] ? process_one_work+0x5e0/0x5e0 > > [ 381.346252] kthread+0x11d/0x140 > > [ 381.346255] ? kthread_create_on_node+0x60/0x60 > > [ 381.346261] ret_from_fork+0x3a/0x50 > > [ 381.346275] irq event stamp: 10302 > > [ 381.346278] hardirqs last enabled at (10301): [] > > _raw_spin_unlock_irq+0x29/0x40 > > [ 381.346282] hardirqs last disabled at (10302): [] > > on_each_cpu_mask+0x49/0x70 > > [ 381.346287] softirqs last enabled at (10262): [] > > cgroup_idr_replace+0x3a/0x50 > > [ 381.346290] softirqs last disabled at (10260): [] > > cgroup_idr_replace+0x1d/0x50 > > [ 381.346293] ---[ end trace b324ba73eb3659f0 ]--- > > > > Reported-by: Andrei Vagin > > Signed-off-by: Roman Gushchin > > Cc: Christoph Lameter > > Cc: Johannes Weiner > > Cc: Michal Hocko > > Cc: Shakeel Butt > > Cc: Vladimir Davydov > > Cc: Waiman Long > > Cc: David Rientjes > > Cc: Joonsoo Kim > > Cc: Pekka Enberg > > --- > > mm/slab.h | 17 +++++++++++++---- > > 1 file changed, 13 insertions(+), 4 deletions(-) > > > > diff --git a/mm/slab.h b/mm/slab.h > > index a4c9b9d042de..c02e7f44268b 100644 > > --- a/mm/slab.h > > +++ b/mm/slab.h > > @@ -294,8 +294,12 @@ static __always_inline int memcg_charge_slab(struc= t page *page, > > memcg =3D parent_mem_cgroup(memcg); > > rcu_read_unlock(); > > > > - if (unlikely(!memcg)) > > + if (unlikely(!memcg || mem_cgroup_is_root(memcg))) { > > + mod_node_page_state(page_pgdat(page), cache_vmstat_idx(= s), > > + (1 << order)); > > + percpu_ref_get_many(&s->memcg_params.refcnt, 1 << order= ); > > return true; >=20 > Should the above be "return 0;" instead of true? Yeah... Good catch! Somehow I missed this previously... I'll send v2 with the fix. Thank you!