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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 37B26C000E X-Stat-Signature: 69o9odrxhqaw4ifme7e8mbgk48echyzt X-Rspam-User: X-HE-Tag: 1720698562-833564 X-HE-Meta: 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 TTkD0em7 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 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: List-Subscribe: List-Unsubscribe: On 7/11/24 4:11 PM, Vlastimil Babka wrote: > On 7/10/24 7:43 AM, alexs@kernel.org wrote: >> From: "Alex Shi (Tencent)" >> >> commit 21c690a349ba ("mm: introduce slabobj_ext to support slab object >> extensions") selected SLAB_OBJ_EXT on MEMCG just for SLAB_MATCH >> memcg_data, that included SLAB_OBJ_EXT for MEMCG. In fact, I didn't see >> the necessary to enable SLAB_OBJ_EXT for MEMCG. >> >> Let's decouple the SLAB_OBJ_EXT from MEMCG and move out >> alloc_slab_obj_exts() definition from SLAB_OBJ_EXT only. To alignment >> the alloc_slab_obj_exts() return 0 for good. change its return value to >> '-1' for always failed with !SLAB_OBJ_EXT. Now we could save unnecessary >> code from MEMCG but !SLAB_OBJ_EXT. >> >> Signed-off-by: Alex Shi (Tencent) > > This seems just wrong to me. The memcg hooks for slab do use obj_ext. You > made alloc_slab_obj_exts() return -1 and that will just fail all memcg > charging (unless alloc profiling selects obj_ext). The kernel will appear to > work, but memcg charging for slab won't happen at all. > > So no, it can't be decoupled for slab, only for pages/folios (patch 1). Hi Vlastimil, Thanks a lot for clarification! Yes, the patch isn't correct. Just forgive my stupidity, why the memcg needs SLAB_OBJ_EXT? And why we need to alloc_slab_obj_exts() at line 3019 with !slab_obj_exts? 3015 for (i = 0; i < size; i++) { 3016 slab = virt_to_slab(p[i]); 3017 3018 if (!slab_obj_exts(slab) && 3019 alloc_slab_obj_exts(slab, s, flags, false)) { 3020 obj_cgroup_uncharge(objcg, obj_full_size(s)); 3021 continue; 3022 } Thanks! Alex > > >> Cc: Randy Dunlap >> Cc: Yoann Congal >> Cc: Masahiro Yamada >> Cc: Petr Mladek >> --- >> init/Kconfig | 1 - >> mm/slab.h | 6 +++--- >> mm/slub.c | 6 +++--- >> 3 files changed, 6 insertions(+), 7 deletions(-) >> >> diff --git a/init/Kconfig b/init/Kconfig >> index 26bf8bb0a7ce..61e43ac9fe75 100644 >> --- a/init/Kconfig >> +++ b/init/Kconfig >> @@ -965,7 +965,6 @@ config MEMCG >> bool "Memory controller" >> select PAGE_COUNTER >> select EVENTFD >> - select SLAB_OBJ_EXT >> help >> Provides control over the memory footprint of tasks in a cgroup. >> >> diff --git a/mm/slab.h b/mm/slab.h >> index 8ffdd4f315f8..6c727ecc1068 100644 >> --- a/mm/slab.h >> +++ b/mm/slab.h >> @@ -559,9 +559,6 @@ static inline struct slabobj_ext *slab_obj_exts(struct slab *slab) >> return (struct slabobj_ext *)(obj_exts & ~OBJEXTS_FLAGS_MASK); >> } >> >> -int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, >> - gfp_t gfp, bool new_slab); >> - >> #else /* CONFIG_SLAB_OBJ_EXT */ >> >> static inline struct slabobj_ext *slab_obj_exts(struct slab *slab) >> @@ -571,6 +568,9 @@ static inline struct slabobj_ext *slab_obj_exts(struct slab *slab) >> >> #endif /* CONFIG_SLAB_OBJ_EXT */ >> >> +int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, >> + gfp_t gfp, bool new_slab); >> + >> static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s) >> { >> return (s->flags & SLAB_RECLAIM_ACCOUNT) ? >> diff --git a/mm/slub.c b/mm/slub.c >> index cc11f3869cc6..f531c2d67238 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -2075,10 +2075,10 @@ alloc_tagging_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, >> >> #else /* CONFIG_SLAB_OBJ_EXT */ >> >> -static int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, >> - gfp_t gfp, bool new_slab) >> +int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, >> + gfp_t gfp, bool new_slab) >> { >> - return 0; >> + return -1; >> } >> >> static inline void free_slab_obj_exts(struct slab *slab) >