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Tue, 10 Dec 2024 08:29:59 +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 vsy4NAf8V2d2HwAAD6G6ig (envelope-from ); Tue, 10 Dec 2024 08:29:59 +0000 Message-ID: <5a047afd-1e9f-4e68-8c8a-d5b0b5506bb3@suse.cz> Date: Tue, 10 Dec 2024 09:29:59 +0100 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: [PATCH] memcg: slub: fix SUnreclaim for post charged objects To: Shakeel Butt , Andrew Morton Cc: Yosry Ahmed , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Meta kernel team References: <20241210040657.3441287-1-shakeel.butt@linux.dev> From: Vlastimil Babka Content-Language: en-US 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: <20241210040657.3441287-1-shakeel.butt@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Level: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; ARC_NA(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; RCPT_COUNT_SEVEN(0.00)[7]; MID_RHS_MATCH_FROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.cz:mid] X-Spam-Score: -4.30 X-Spam-Flag: NO On 12/10/24 05:06, Shakeel Butt wrote: > Large kmalloc directly allocates from the page allocator and then use > lruvec_stat_mod_folio() to increment the unreclaimable slab stats for > global and memcg. However when post memcg charging of slab objects was > added in commit 9028cdeb38e1 ("memcg: add charging of already allocated > slab objects"), it missed to correctly handle the unreclaimable slab > stats for memcg. > > One user visisble effect of that bug is that the node level > unreclaimable slab stat will work correctly but the memcg level stat can > underflow as kernel correctly handles the free path but the charge path > missed to increment the memcg level unreclaimable slab stat. Let's fix > by correctly handle in the post charge code path. > > Fixes: 9028cdeb38e1 ("memcg: add charging of already allocated slab objects") That's a 6.12-rc1 commit so I'm adding cc stable. > Signed-off-by: Shakeel Butt Queued in slab/for-next-fixes, thanks! Vlastimil > --- > mm/slub.c | 21 ++++++++++++++++++--- > 1 file changed, 18 insertions(+), 3 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index f62c829b7b6b..88bf2bf51bd6 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2189,9 +2189,24 @@ bool memcg_slab_post_charge(void *p, gfp_t flags) > > folio = virt_to_folio(p); > if (!folio_test_slab(folio)) { > - return folio_memcg_kmem(folio) || > - (__memcg_kmem_charge_page(folio_page(folio, 0), flags, > - folio_order(folio)) == 0); > + int size; > + > + if (folio_memcg_kmem(folio)) > + return true; > + > + if (__memcg_kmem_charge_page(folio_page(folio, 0), flags, > + folio_order(folio))) > + return false; > + > + /* > + * This folio has already been accounted in the global stats but > + * not in the memcg stats. So, subtract from the global and use > + * the interface which adds to both global and memcg stats. > + */ > + size = folio_size(folio); > + node_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B, -size); > + lruvec_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B, size); > + return true; > } > > slab = folio_slab(folio);