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charset="us-ascii" Content-ID: <54289716AAA5304A98D8988A365F07C7@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: f342b92d-bb98-4dfa-f87f-08d75985fde5 X-MS-Exchange-CrossTenant-originalarrivaltime: 25 Oct 2019 20:00:32.4482 (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: /VaoAQjvEz6SC6rbfYmLzsA00foy3TvdSZ8WIoKg+EO75AJrWjL8W5Ns3XbES5ea X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR15MB2578 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,1.0.8 definitions=2019-10-25_10:2019-10-25,2019-10-25 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 phishscore=0 adultscore=0 mlxlogscore=999 impostorscore=0 suspectscore=0 clxscore=1015 priorityscore=1501 bulkscore=0 malwarescore=0 mlxscore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1908290000 definitions=main-1910250182 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 25, 2019 at 03:41:18PM -0400, Johannes Weiner wrote: > On Thu, Oct 17, 2019 at 05:28:13PM -0700, Roman Gushchin wrote: > > +static inline struct kmem_cache *memcg_slab_pre_alloc_hook(struct kmem= _cache *s, > > + struct mem_cgroup **memcgp, > > + size_t size, gfp_t flags) > > +{ > > + struct kmem_cache *cachep; > > + > > + cachep =3D memcg_kmem_get_cache(s, memcgp); > > + if (is_root_cache(cachep)) > > + return s; > > + > > + if (__memcg_kmem_charge_subpage(*memcgp, size * s->size, flags)) { > > + mem_cgroup_put(*memcgp); > > + memcg_kmem_put_cache(cachep); > > + cachep =3D NULL; > > + } > > + > > + return cachep; > > +} > > + > > static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, > > struct mem_cgroup *memcg, > > size_t size, void **p) > > { > > struct mem_cgroup_ptr *memcg_ptr; > > + struct lruvec *lruvec; > > struct page *page; > > unsigned long off; > > size_t i; > > @@ -439,6 +393,11 @@ static inline void memcg_slab_post_alloc_hook(stru= ct kmem_cache *s, > > off =3D obj_to_index(s, page, p[i]); > > mem_cgroup_ptr_get(memcg_ptr); > > page->mem_cgroup_vec[off] =3D memcg_ptr; > > + lruvec =3D mem_cgroup_lruvec(page_pgdat(page), memcg); > > + mod_lruvec_memcg_state(lruvec, cache_vmstat_idx(s), > > + s->size); > > + } else { > > + __memcg_kmem_uncharge_subpage(memcg, s->size); > > } > > } > > mem_cgroup_ptr_put(memcg_ptr); >=20 > The memcg_ptr as a collection vessel for object references makes a lot > of sense. But this code showcases that it should be a first-class > memory tracking API that the allocator interacts with, rather than > having to deal with a combination of memcg_ptr and memcg. >=20 > In the two hunks here, on one hand we charge bytes to the memcg > object, and then handle all the refcounting through a different > bucketing object. To support that in the first place, we have to > overload the memcg API all the way down to try_charge() to support > bytes and pages. This is difficult to follow throughout all layers. >=20 > What would be better is for this to be an abstraction layer for a > subpage object tracker that sits on top of the memcg page tracker - > not unlike the page allocator and the slab allocators themselves. >=20 > And then the slab allocator would only interact with the subpage > object tracker, and the object tracker would deal with the memcg page > tracker under the hood. Yes, the idea makes total sense to me. I'm not sure I like the new naming (I have to spend some time with it first), but the idea of moving stocks and leftovers to the memcg_ptr/obj_cgroup level is really good. I'll include something based on your proposal into the next version of the patchset. Thank you!