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Tue, 20 Jan 2026 12:55:09 +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 ge/DIC17b2kMAgAAD6G6ig (envelope-from ); Tue, 20 Jan 2026 12:55:09 +0000 Message-ID: <8bd3c3e8-9865-4467-86d5-17d891f6f21b@suse.cz> Date: Tue, 20 Jan 2026 13:55:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] slab: replace cache_from_obj() with inline checks Content-Language: en-US To: Hao Li Cc: Harry Yoo , Eric Dumazet , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev References: <20260120-b4-remove_cache_from_obj-v1-1-ace30c41eecf@suse.cz> 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+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: zpqz5fsoth49mr88gx7e41m5rmph7thu X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 5A50A1C0006 X-Rspam-User: X-HE-Tag: 1768913711-381665 X-HE-Meta: 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 wshRElkj a01va2iZCWLb7H8NmrM2fPZ6SiYgEMOcB7+4Htg8Zoaj7g5ZCf+sy2dcOwsq6WV3fUwJk/acH9pMg/OBnaS/0xgAwTPUwFSmHyZ7AbsI/9Itq60yu8x/Bl65axQ+FcT4LDpCW1Lc2lrmoCqLJSvYVwHgLtnofKfjR+U7JldsOQxIgbqsdjXCUEA8XyHgvCFGPbc2nsZuJUiSb6i4AdgP+Cvc2DjnXfCuNh+12C7B4ghJ4P3GoC/fdXpouhqX3jiF0QYHMgx6ZzAbeXXI1LVC7KLJgMloQjQpneNh1Ub6IOqqvs2w= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 1/20/26 12:57, Hao Li wrote: >> @@ -6774,11 +6770,21 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x) >> */ >> void kmem_cache_free(struct kmem_cache *s, void *x) >> { >> - s = cache_from_obj(s, x); >> - if (!s) >> - return; >> + struct slab *slab; >> + >> + slab = virt_to_slab(x); >> + >> + if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) || >> + kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) { >> + >> + if (unlikely(!slab || (slab->slab_cache != s))) { >> + warn_free_bad_obj(s, x); > > Just to make sure I'm understanding correctly, are we intentionally not > releasing the object x in this case? Thanks. Yes, it means something went wrong so it's better not to do anything. That was true before this patch as well. >> + return; >> + } >> + } >> + >> trace_kmem_cache_free(_RET_IP_, x, s); >> - slab_free(s, virt_to_slab(x), x, _RET_IP_); >> + slab_free(s, slab, x, _RET_IP_); >> } >> EXPORT_SYMBOL(kmem_cache_free); >> >> @@ -7305,7 +7311,7 @@ int build_detached_freelist(struct kmem_cache *s, size_t size, >> df->s = slab->slab_cache; >> } else { >> df->slab = slab; >> - df->s = cache_from_obj(s, object); /* Support for memcg */ >> + df->s = s; >> } >> >> /* Start new detached freelist */ >> >> --- >> base-commit: 0f61b1860cc3f52aef9036d7235ed1f017632193 >> change-id: 20260120-b4-remove_cache_from_obj-190fcaf16789 >> >> Best regards, >> -- >> Vlastimil Babka >>