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b=QrnqwayXlJrmoiZ0u1sB6zSrdj3atfwQyJsUJxcCMfxbHkmnZnv8ZLcdb4R9RpHBB FvQwOsQEGHluLfqGsSA6HgV0J27MWpP15ojOdmv22bKAWAx05QwuPO0y9xnXVC/WHN q3//A/panHvy6AOi4VBdoAtal6baa6STqbmSVoAwf0h5OCPvHSeDFREThUCsE/ZvIo GRywI7kYLfR2dIpMW0D1bgFxqn8o/tRVNyHirXRzQqQW2WEZhSTSeo1ZzAFdsEB1M7 dWISBVl056PFk58nrAodqbCurGD+PmvhYzGuRKAY9SLP9i2Qas1pEnOC9/sI05LaIe zt6dFVgml2+Hg== Message-ID: Date: Thu, 23 Jul 2026 11:30:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 12/13] mm/slab: add cache_ and slab_needs_objcg() helpers Content-Language: en-US To: Hao Li Cc: Harry Yoo , Suren Baghdasaryan , Shakeel Butt , Alexander Potapenko , Marco Elver , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org References: <20260720-b4-objext_split-v2-0-2fa7c6f60dbe@kernel.org> <20260720-b4-objext_split-v2-12-2fa7c6f60dbe@kernel.org> 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 586A140005 X-Stat-Signature: 73ojb6bosyeqfzh7jg3cojsorepk5irj X-Rspam-User: X-HE-Tag: 1784799055-128754 X-HE-Meta: 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 exAahaZR F51C+WbAo+r25Ruuf7qtEIHEG1i3tiIDvlu81iwpZQWhp7s2rPqAH/HFtFk3ZQGnduJ76p19uvX8Po0Lxn+cYqHiMyLH63lq8CyraM9kaMpj7AGZz5X1srA9SADZmk4zG5AWWww21YrFwpey3gGAT6aXLOUznOuZEBS+2jclSEpe8WrYa6OM/ovzXLu5Pu8wm/1naBpUjOcukcWmqt65zoDV03NmCZto/VF9O8h0XT9GnTAH7fYPzLWosxW/hCAxpWj2hMDxyPNoj60eFZ42mUFur9S3KRqS24uHpsAjT51uVw8q3SkZStFTdjg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/23/26 11:25, Hao Li wrote: > On Mon, Jul 20, 2026 at 04:16:26PM +0200, Vlastimil Babka (SUSE) wrote: >> @@ -359,6 +359,13 @@ struct kmem_cache *__kmem_cache_create_args(const char *name, >> goto out_unlock; >> } >> >> + /* >> + * For now we assume any cache can be used with __GFP_ACCOUNT and thus >> + * may need to store objcg pointers for objects >> + */ >> + if (!mem_cgroup_kmem_disabled()) >> + flags |= SLAB_MAY_ACCOUNT; > > if memcg itself is disabled via `cgroup_disable`, mem_cgroup_kmem_disabled() > still return false, so maybe we can use: Aha, but then shouldn't rather mem_cgroup_kmem_disabled() take that into account on its own? > if (!mem_cgroup_disabled() && !mem_cgroup_kmem_disabled()) > flags |= SLAB_MAY_ACCOUNT; > >> + >> /* Fail closed on bad usersize of useroffset values. */ >> if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) || >> WARN_ON(!args->usersize && args->useroffset) || >> @@ -984,11 +991,19 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type) >> #endif >> >> /* >> - * If CONFIG_MEMCG is enabled, disable cache merging for >> - * KMALLOC_NORMAL caches. >> + * 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. >> + * >> + * In other cases the kmalloc cache may end up being used for a >> + * __GFP_ACCOUNT allocation so mark it as such >> */ >> - if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_NORMAL)) >> - flags |= SLAB_NO_MERGE; >> + if (!mem_cgroup_kmem_disabled()) { > > the same as above > > Others look good to me. > > Reviewed-by: Hao Li Thanks! > >> + if (type == KMALLOC_NORMAL && KMALLOC_RECLAIM != KMALLOC_NORMAL) >> + flags |= SLAB_NO_MERGE; >> + else >> + flags |= SLAB_MAY_ACCOUNT; >> + } >> >> if (minalign > ARCH_KMALLOC_MINALIGN) { >> aligned_size = ALIGN(aligned_size, minalign); >> diff --git a/mm/slub.c b/mm/slub.c >> index d78d3e50c877..30435e2509ea 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -2557,7 +2557,7 @@ bool memcg_slab_post_charge(void *p, gfp_t flags) >> * of slab_obj_exts being allocated from the same slab and thus the slab >> * becoming effectively unfreeable. >> */ >> - if (is_kmalloc_normal(s)) >> + if (!cache_needs_objcg(s)) >> return true; >> >> /* Ignore already charged objects. */ >> @@ -3435,6 +3435,10 @@ static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, >> >> slab->objects = oo_objects(oo); >> >> +#ifdef CONFIG_64BIT >> + if (cache_needs_objcg(s)) >> + slab->obj_exts_needs_objcg = 1; >> +#endif >> slab->slab_cache = s; >> >> kasan_poison_slab(slab); >> >> -- >> 2.55.0 >> >