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Thu, 11 Jul 2024 08:11:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id eszMF7qTj2YSHgAAD6G6ig (envelope-from ); Thu, 11 Jul 2024 08:11:38 +0000 Message-ID: Date: Thu, 11 Jul 2024 10:11:38 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REF PATCH v3 2/2] mm/slab: decouple the SLAB_OBJ_EXT from MEMCG Content-Language: en-US To: alexs@kernel.org, Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Randy Dunlap , Yoann Congal , Masahiro Yamada , Petr Mladek , Suren Baghdasaryan References: <20240710054336.190410-1-alexs@kernel.org> <20240710054336.190410-2-alexs@kernel.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20240710054336.190410-2-alexs@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spamd-Result: default: False [-2.79 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; XM_UA_NO_VERSION(0.01)[]; TAGGED_RCPT(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_TO(0.00)[kernel.org,linux-foundation.org,linux.com,google.com,lge.com,linux.dev,gmail.com,kvack.org,vger.kernel.org]; RCPT_COUNT_TWELVE(0.00)[15]; MID_RHS_MATCH_FROM(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email] X-Spam-Flag: NO X-Spam-Score: -2.79 X-Spam-Level: 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). > 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)