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charset="us-ascii" Content-ID: <5100D4FBDDC1884F9DF504E70C7535F7@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: c2cc57a6-2520-4323-da96-08d724f71f6e X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Aug 2019 22:46:50.0644 (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: BlbQ65gAUrBAiwo+wMjJVTMJaNcoLASkvIm1VDIgZBn6hkfdLybyipJvLoxdYQLf X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR15MB3529 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-19_04:,, 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=665 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908190226 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 19, 2019 at 03:27:44PM -0700, Andrew Morton wrote: > On Mon, 19 Aug 2019 13:23:37 -0700 Roman Gushchin wrote: >=20 > > I've noticed that the "slab" value in memory.stat is sometimes 0, > > even if some children memory cgroups have a non-zero "slab" value. > > The following investigation showed that this is the result > > of the kmem_cache reparenting in combination with the per-cpu > > batching of slab vmstats. > >=20 > > At the offlining some vmstat value may leave in the percpu cache, > > not being propagated upwards by the cgroup hierarchy. It means > > that stats on ancestor levels are lower than actual. Later when > > slab pages are released, the precise number of pages is substracted > > on the parent level, making the value negative. We don't show negative > > values, 0 is printed instead. > >=20 > > To fix this issue, let's flush percpu slab memcg and lruvec stats > > on memcg offlining. This guarantees that numbers on all ancestor > > levels are accurate and match the actual number of outstanding > > slab pages. > >=20 > > Fixes: fb2f2b0adb98 ("mm: memcg/slab: reparent memcg kmem_caches on cgr= oup removal") > > Signed-off-by: Roman Gushchin > > Cc: Johannes Weiner > > Cc: Michal Hocko > > Cc: Vladimir Davydov >=20 > [1/3] and [3/3] have cc:stable. [2/3] does not. However [3/3] does > not correctly apply without [2/3] having being applied. Right, [2/3] is required by slab kmem reparenting, which appeared in 5.3. I can rearrange [2/3] and [3/3] so that first two patches will have cc table and apply correctly. Let me do this, I'll send v3 shortly. Thanks!