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b=J3QpNxlK+VfRxOQBqJ3Un2Zp2XZu+SBFJoDzQKLY+1pcxm5h5JkuCmJePpKOi+bV4 FcmoPvyk+dtTe+rj/Sgm5BobMog+m8r01RYWJmkuIOv+y4gep+fqYziq43dFNUuz08 lLyDEkcWlpC6SlWuyKtQIEO8wMa0Bj15QBwbmJLBSleZ56WMyiWv9K9b4vJFYfwSJc ZsEXhYV9Hl9MkVd7PMqi9AWwi1zYmgK3uH6Yc3HURviDObyLSXClZp2D/pc8IZU6Uw cTlTiafXjZZVXG2b4SciG2SOTAWlJX6xnavIdMVZezkTWpn7jQ8fiMfbMCtI7hWExJ AErWQyHw/crHA== Message-ID: Date: Thu, 16 Jul 2026 15:58:19 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 05/12] mm/slab: abstract slabobj_ext.objcg access Content-Language: en-US To: Suren Baghdasaryan Cc: Harry Yoo , Hao Li , 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: <20260715-b4-objext_split-v1-0-9a49c4ccf4c3@kernel.org> <20260715-b4-objext_split-v1-5-9a49c4ccf4c3@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: 8bit X-Rspamd-Queue-Id: 928A240007 X-Stat-Signature: rbfdtui6371w6uzmc6ks4kno6hwsftoi X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1784210304-827576 X-HE-Meta: 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 OuCArImC agxereMejCtSmMPCcWgaTGeJuzUAaq7sCcYECpz6u5S1lAgS1kBB8UUgLU3ETH8zyUxfVGB1LzPUWHZfOQ+dODN54jt9GvQIp7kNqoCKGyINrpvEGmniUdc75tyeBiyzYCaYZV+/gCEkxcQdthRIzUjl09O9EFFUv5MkH1wxQcj+NCiksol9g0pUCTovVada0DM3NCD7HvF8Q9FExRFyeIFaUXuADanoSwG6DR9thRPvKTCsZxsnH0aPguV89FFAcKuS+GaaOAr4qGwMRXGb11bwSX2kCWsbn3ttznuqAtJA84B6tyJOm71hUsxLPR3QzMi+d2O2tz5RJHqruE61VPlnE+goilz7/g/r0 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/16/26 03:27, Suren Baghdasaryan wrote: > On Wed, Jul 15, 2026 at 3:11 AM Vlastimil Babka (SUSE) > wrote: >> --- a/mm/slab.h >> +++ b/mm/slab.h >> @@ -555,7 +555,7 @@ static inline bool need_kmalloc_no_objext(void) >> */ >> struct slabobj_ext { >> #ifdef CONFIG_MEMCG >> - struct obj_cgroup *objcg; >> + struct obj_cgroup *_objcg; >> #endif >> #ifdef CONFIG_MEM_ALLOC_PROFILING >> union codetag_ref ref; >> @@ -661,6 +661,13 @@ slab_obj_ext(struct kmem_cache *s, struct slab *slab, unsigned long obj_exts, >> return kasan_reset_tag(obj_ext); >> } >> >> +#ifdef CONFIG_MEMCG >> +static inline struct obj_cgroup **slab_obj_ext_objcgp(struct slabobj_ext *obj_ext) > > I understand why you need to return obj_cgroup** but maybe instead we > can have a separate setter function and just return a pointer here? Yeah I rewrote it now and it looks better. Thanks! It ended up like this due to some previous attempt I made. > That would also help catch cases when someone wants to set > obj_ext._objcg that was optimized away (for that the setter would need > an additional parameter to identify whether we allocated optimized > objext vector). It would need passing the slab parameter to assert slab_obj_ext_has_codetag() in debug mode. I don't think it's worth it given the get/set is only called from few specialized places. > >> +{ >> + return &obj_ext->_objcg; >> +} >> +#endif >> + >> int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, >> gfp_t gfp, unsigned int alloc_flags); >> >> diff --git a/mm/slub.c b/mm/slub.c >> index 5e3f53bcd0d3..48e10198a3ce 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -2523,7 +2523,7 @@ bool memcg_slab_post_charge(void *p, gfp_t flags) >> if (obj_exts) { >> get_slab_obj_exts(obj_exts); >> obj_ext = slab_obj_ext(s, slab, obj_exts, p); >> - if (unlikely(obj_ext->objcg)) { >> + if (unlikely(*slab_obj_ext_objcgp(obj_ext))) { >> put_slab_obj_exts(obj_exts); >> return true; >> } >> >> -- >> 2.55.0 >>