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X-MS-Exchange-AntiSpam-MessageData: =?us-ascii?Q?O8/8Cs3iJ+x6TE4hT0KsOreOsotbgB+j5cGTA8h165sM3xqHaeAF5/avJ4a9?= =?us-ascii?Q?7QdnmvBlsF/isfv9YTsPlQ3Sgtrs0Ah+iE3sflTltyT5wKz2gYEBADss6BnD?= =?us-ascii?Q?VUwLCQ296rhXwG1F4Qz2BC7wB+UYCpeELmxKkoZeqWNFhwQtJYgchyWZ5Ff6?= =?us-ascii?Q?95gXuc6QEVy7jgEXAEIS661c5RJGQHovpQ6elYKSypCLsOgEdqRSFbA7vWuP?= =?us-ascii?Q?uRY+GiGJ7cpWGlByiqTUvAXZvFA+XuAB9qRezvaGDbgrAJDFI3W08BY9FU50?= =?us-ascii?Q?+fhAQHtyA7qgOlghQevZ0+sJ8PKt+vnI6r/4abNTjhTgj/07bcKYw32CS0PY?= =?us-ascii?Q?7mTnRkvQXL1u5njQCCUKt0rcTA5nYjp3bJGBUNFIViTr42KFrSzH3i7yXBK9?= =?us-ascii?Q?ld/ZvGM2eLrcpHOn7suoGVjzHNWYyaze+3YYI8YBjbO8IuVuJgSS46XHdW2z?= =?us-ascii?Q?joSHw+HHRlSEcxeSpk5oTkizu6ek7HsT9cRdhaUtNX6Wz3skoimJurhP8n2+?= =?us-ascii?Q?pMoo1UlaynMvTITQOf4b3DMI0tFaNqHre97i8VGygwWSq12+uwuFC+FLa/1E?= =?us-ascii?Q?TB/tk1daYJgdqBQXSbuvn13idSORky6u5i0dE3k8JF1qzV46nropjA6LfaCv?= =?us-ascii?Q?ZgDNqAV+96yUfyPrf7ZFi+ACMm+bsz/ZUaupFptY+2xjmzSI9Y4dNV3QeIjR?= =?us-ascii?Q?U/TkhK4Yu1Lw1+lMDvvovrMAQwiOHIuVgkyC0j7rDw0+fcyv2pJNF0TKdmRI?= =?us-ascii?Q?cWo30DDflEQxeMinKACy/RfNNxcn0W7Um1UdQ2jPbVBPe2fRW146UaCfVCiG?= =?us-ascii?Q?DVAxqXa4B218l4v+nsPbCT2OrPGQoyhSyQrj9AGK6SkdFpQ28rbT4El9DYk7?= =?us-ascii?Q?6dM+UQ5bQntV5cTjWCczOLZ8uUTZBedmSphR+GQ3yO7Cw8c3rgNoLfvs2WoX?= =?us-ascii?Q?AFv3JYCH/BCozNiPxTv9M79FBDp119cAKuTnYnWEDs84GtxzHcXDJLzwnDcw?= =?us-ascii?Q?ZLGS5/bgHh+WemWXLgelmNXfxcN9NwQsNTB9yjDBOxOU41pgKmMWhR597Bzy?= =?us-ascii?Q?YaQJT8tKmm4UBuwTXEn0y0LER/aM+4z0Y7C4HCKmfi7mnnYvzPXSXptYyMC9?= =?us-ascii?Q?i8tFoxNhPS6NRaVS07fuFClyeDi5DPgkXS0wSes9gO7rOHIF6Oa0lfZV1bb+?= =?us-ascii?Q?OWCNpksQjYbqhx6WA0TeOXxyPMytlqCFTCk8QLuVFQyBFtKrCmov5rFXiN5G?= =?us-ascii?Q?ncChFP6P8hM8HT6sds5DXeCCFozC475nC8QnTl8s45mbRZWYtkvI52rfHxED?= =?us-ascii?Q?avKXs0v1piKFNo+pHMIuWb0YE5B9f7ogscvhrOK3IOtr4w=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 1ab1d3ce-cc23-4119-2f88-08d91fa50a9c X-MS-Exchange-CrossTenant-AuthSource: BYAPR15MB4136.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 May 2021 17:46:35.9847 (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: f0p9MTM+1HRo4awQDeECd9amVM0bYI7F2W/h/Bmjb2VrWyltKb9PInSUEJHYp24l X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2344 X-OriginatorOrg: fb.com X-Proofpoint-GUID: uv1Oy2Y6OpXyM5xlQ4tjLZlU39bO52FN X-Proofpoint-ORIG-GUID: uv1Oy2Y6OpXyM5xlQ4tjLZlU39bO52FN X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-05-25_08:2021-05-25,2021-05-25 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 adultscore=0 mlxlogscore=923 phishscore=0 clxscore=1015 priorityscore=1501 mlxscore=0 spamscore=0 impostorscore=0 suspectscore=0 malwarescore=0 lowpriorityscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105250110 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 21, 2021 at 03:00:55PM +0800, Muchun Song wrote: > In the previous patch, we know how to make the lruvec lock safe when the > LRU pages reparented. We should do something like following. > > memcg_reparent_objcgs(memcg) > 1) lock > // lruvec belongs to memcg and lruvec_parent belongs to parent memcg. > spin_lock(&lruvec->lru_lock); > spin_lock(&lruvec_parent->lru_lock); > > 2) do reparent > // Move all the pages from the lruvec list to the parent lruvec list. > > 3) unlock > spin_unlock(&lruvec_parent->lru_lock); > spin_unlock(&lruvec->lru_lock); > > Apart from the page lruvec lock, the deferred split queue lock (THP only) > also needs to do something similar. So we extracted the necessary 3 steps > in the memcg_reparent_objcgs(). > > memcg_reparent_objcgs(memcg) > 1) lock > memcg_reparent_ops->lock(memcg, parent); > > 2) reparent > memcg_reparent_ops->reparent(memcg, reparent); > > 3) unlock > memcg_reparent_ops->unlock(memcg, reparent); > > Now there are two different locks (e.g. lruvec lock and deferred split > queue lock) need to use this infrastructure. In the next patch, we will > use those APIs to make those locks safe when the LRU pages reparented. > > Signed-off-by: Muchun Song > --- > include/linux/memcontrol.h | 11 +++++++++++ > mm/memcontrol.c | 49 ++++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 58 insertions(+), 2 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 228263f2c82b..b12847b0be09 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -355,6 +355,17 @@ struct mem_cgroup { > /* WARNING: nodeinfo must be the last member here */ > }; > > +struct memcg_reparent_ops { > + struct list_head list; > + > + /* Irq is disabled before calling those functions. */ > + void (*lock)(struct mem_cgroup *memcg, struct mem_cgroup *parent); > + void (*unlock)(struct mem_cgroup *memcg, struct mem_cgroup *parent); > + void (*reparent)(struct mem_cgroup *memcg, struct mem_cgroup *parent); > +}; > + > +void __init register_memcg_repatent(struct memcg_reparent_ops *ops); > + > /* > * size of first charge trial. "32" comes from vmscan.c's magic value. > * TODO: maybe necessary to use big numbers in big irons. > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index a48403e5999c..f88fe2f06f5b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -330,6 +330,41 @@ static struct obj_cgroup *obj_cgroup_alloc(void) > return objcg; > } > > +static LIST_HEAD(reparent_ops_head); Because this list is completely static, why not make a build-time initialized array instead? I guess it's a more canonical way of solving problems like this. The proposed API looks good to me.