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imf20.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=W6kuST3N; spf=pass (imf20.hostedemail.com: domain of vbabka@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=vbabka@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794402525; b=xGEicaABlhXvk89smMSmCUkx7e/ZdiK8cJRcj8vsUpIuGQIUOkhLCyrFuDBxQpEc5zhCkM QWiIpT9atNUtLwTXxabx8waFNDjxIID4DEF2ZhoXx4gN5zukUR6vBv+/suSBDhefHO8+5I 0Ne7cEJSEUj/5iIcu2NsqgSX+SpZpeQ= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3E9F640C04; Wed, 11 Nov 2026 13:08:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 536EF1F00A05; Wed, 11 Nov 2026 13:08:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794402524; bh=tpSt5JkGUaHCP8XlikkEOI4qJddO1S2MUXWY1pm1gq8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=W6kuST3NNP4zzA9PqmXm/bYJ6yoRhEgKl5fNUQn6dha9mMZiyvNhUUICtqwe3+ArG jrSjuVs6BfBQGx22OPJQDQ77+zIoHH2HjoU2ZvMA72U2kcHSkaIJPXdd7WX8Q6lU23 BvsgBMhjHnKrtcDHA0gHVEVcKkuv7cyNUTCCbadw4goRnxkbFWPRAj5QxKya1CySU1 vhoM+ye5tViT7u0sZFpSC8q3yi9BbrZSS0jKAptLmf2YYRwMsQ1ePzHf2uCedCXW4f /KreGp+leeCIRPhMfpge9Ms4JosjH+/kYUEU1/2xKHMyvkoAXWxY72zws1fLN5KnlT mk5wUibYF1QZg== Message-ID: Date: Wed, 11 Nov 2026 14:08:40 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/slab: don't set SLAB_MAY_ACCOUNT for KMALLOC_PARTITION_CACHES Content-Language: en-US To: Hao Li , harry@kernel.org, akpm@linux-foundation.org Cc: cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Suren Baghdasaryan References: <20261111125628.375624-1-hao.li@linux.dev> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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 BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <20261111125628.375624-1-hao.li@linux.dev> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: rrq37kuc9bx3o8d8eepfpz64ug9xp9b3 X-Rspamd-Server: rspam01 X-Rspam-User: X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: 455021C0007 X-HE-Tag: 1794402525-86416 X-HE-Meta: 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 5mh1K9hZ KL1lBhBtxxiT3KZHSbkEQC/R6X9BCvRhYZeK0zuZpiS3OxmWM9XMEEP6lfSAVZ6mSrb1H1oBoRzWOHr9wgTJwSIMe9wgh8qdR6c2ZTucwoYyJsQUklHCICjvD9/varkRVvhRUCEtZVnj51T0bM4NX1NlbVEhgwmCXQ6ZQ0KcxXyTdzw9Hn8YLRBU3xZ+BPtQ5b8EHzfSOuCpzgqdSc73qLRO1SU7J3mlgfQRGFKm7e3+kdGhdB8Ggz61H7AxpdmZxsBmHkxhsMZN8maFxdOIzw0pZL/p7RKRE+gLHhQqTzWHzJ7r7uQT31C1LYefneHMzp50/bqmLZ5+sdFs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/11/26 13:49, Hao Li wrote: > An allocation with __GFP_ACCOUNT set (without __GFP_DMA or > __GFP_RECLAIMABLE) is redirected to KMALLOC_CGROUP and will never hit > KMALLOC_NORMAL or KMALLOC_PARTITION_CACHES. Consequently, neither of > these caches requires objcg slots in obj_exts. > > While KMALLOC_NORMAL already skips setting SLAB_MAY_ACCOUNT, > KMALLOC_PARTITION_CACHES still carries it unnecessarily. > > Extend the check to skip KMALLOC_PARTITION_CACHES as well, saving > unnecessary objcg slots in obj_exts. > > Signed-off-by: Hao Li Reviewed-by: Vlastimil Babka (SUSE) > --- > This doesn't seem like a real bug to me, just a small waste of memory, so I > didn't add a Fixes tag. Hmm I'd add Fixes: 7def2e8549e5 ("mm/slab: add cache_ and slab_needs_objcg() helpers") The question is whether cc stable as well. 7.3 LTS will be used for Android and IIRC they have memory allocation profiling enabled. Not sure about kmalloc partitions. Cc'ing Suren. > --- > mm/slab_common.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 2befd24b4d09..f0ea1fa178e7 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -1000,16 +1000,18 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type) > #endif > > /* > - * If memcg_kmem is enabled and this is a KMALLOC_NORMAL cache and not > - * aliased with any other type, make sure it's never merged with any other > - * cache. > + * If memcg_kmem is enabled and this is a KMALLOC_NORMAL or > + * KMALLOC_PARTITION_CACHES cache and not aliased with any other type, > + * make sure it's never merged with any other cache. > * > * In other cases the kmalloc cache may end up being used for a > * __GFP_ACCOUNT allocation so mark it as such. The exception is a > * KMALLOC_NO_OBJ_EXT cache. > */ > if (!mem_cgroup_kmem_disabled()) { > - if (type == KMALLOC_NORMAL && KMALLOC_RECLAIM != KMALLOC_NORMAL) > + if (type >= KMALLOC_PARTITION_START && > + type <= KMALLOC_PARTITION_END && > + KMALLOC_RECLAIM != KMALLOC_NORMAL) > flags |= SLAB_NO_MERGE; > else if (!(flags & SLAB_NO_OBJ_EXT)) > flags |= SLAB_MAY_ACCOUNT;