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Wed, 10 Sep 2025 21:12:49 +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 srKPHNHpwWhMGQAAD6G6ig (envelope-from ); Wed, 10 Sep 2025 21:12:49 +0000 Message-ID: Date: Wed, 10 Sep 2025 23:12:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 03/22] slab: Remove dead code in check_slab() Content-Language: en-US To: Matthew Wilcox , Harry Yoo Cc: Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org References: <20250829154728.3397606-1-willy@infradead.org> <20250829154728.3397606-4-willy@infradead.org> 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-Rspamd-Action: no action X-Rspamd-Queue-Id: A0C4814000C X-Rspam-User: X-Rspamd-Server: rspam07 X-Stat-Signature: o4gakkcz587yyafhdm6a5hwgiienm3h6 X-HE-Tag: 1757538771-424965 X-HE-Meta: U2FsdGVkX1/4tfg06Z9wSmS5TfPEuSoO98EV9d3vIlzku+59L3nRRuR25K8KZZEDiVVgNv+v3PVdo7FeHKgOP4MvUKwqz03HibTP8uAz6dstOY7/MErmoyPOheXaXgSmPHFQ1/VYzr/1qnjJywcCSHJIPMSXSWMNa/VGGcywQ9Y4Q0qqk2JFCKjtft2b882BY33NWYHtsVfzxRHQ69izbG/F4N5TfNI1U4jucnu/4m50pJ1n1opL71RMPVUgwW/c3ruKKzOirv7Co6tvobXWk6mttd2WVBphe+Tfogu8fhhEX0MxEVa74CCRK/0z4MpCmCvakxcX/sol37puFJbRUoytikjvBsAVICY1ypV7HHhnOqtxwT2ubgMO23xYL/6EZt6kqqI6MIWkOVizr9QRn8iVA6YCyGvju88FwUlGHqdgkrnWUX8MtuYNZfys/QNiqnLZSIiPhE6gFA5aFfFqplXTBoNi6lss5ir8HcEBdQ5WYxJxJdLSBkuZx7a1efUvSNNRBfof7a2sLENdMk4h671jBSQqnvinmUsk+LEn9ChbChD1MJ5SI/nO9l2DGcsyZLAVylUfl8FhoqbJ1KoZYkbp6ESDPJf5aRdMz89OvY/F7axbaPuCvUKQJ3BR1dA6GhumwsGzKmOByLLUFl3pJYPT/5aImbHCGDlxfOvwpXBcsJylkob/RgIuGBqrrub6YRNhPT73N90j19t7iGMa2X96+YjUPGsh7578K4BirSy04ckPATy/o+r/rJa9wY/1SmRyYvucZ/rha68Jh5CIK55+nV0BInOBDEQmvFnmebLY8MQd7mVzG45441oNUzDX86ZS8lhvRwZh29sDTWqiMAARvrfjWQn24mvUZrvGdS3Y5u+gEsW5jVSoqognrv6ErTiq1RBuElfvNEktdvUEo0lUaA8yIImdmhDfvOjYWRNR8eK3Q8skn9Il8s/cnP7OKcRqcjB1pPoSTWPWzmJ Tbyk5cwq 7KRLrJ8EMEoOYWcIx7VQ+dPuRaAf/LugqMA7tPUISqFnMDv8PHnvgHIcpghn69Io57RM07536tR+jIZLrCpXFK/pSz3eA+R+I7cfdJIIaW/km2XsRh9DNJ61vqlY2B5Hmkjs2uQl1I3mkNr7nydWhtnm5zoPxZ1A4CZI4Ro/K0QX2t4W15q7fpxIIyoBZaWK6AziuL009n6Ssky5s9UBS0AtDKMkPKY+IX6XGoU9gqt94ikR1VtXRtYEts0ZpByIiMq59x4DhhGoA7nYUOltwTwZI2+ATGo9L4lqRmtBqhzgTo9g= 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 9/10/25 13:39, Matthew Wilcox wrote: > On Wed, Sep 10, 2025 at 08:21:18PM +0900, Harry Yoo wrote: >> Side question: if someone wants to (though I don't see much value in it) >> iterate over n->partial and check whether a slab is corrupted and no >> longer a slab, should they convert it from slab to page and then check >> PageSlab()? Your question sounds like a hypothetical scenario, but that's actually what writing to sysfs "validate" file of a cache does, no? One could say that in validate_slab() we don't "already know the slab passed in is a valid slab". > I don't think so. There are probably other objects allocated from the > corrupt slab, and they might get freed at some point. If they are, > we'll want to handle them gracefully (after all, the caller of kfree() > probably did nothing wrong) and not print a warning suggesting that > someone's calling kfree() on a non-slab pointer. In case of validate_slab() it wouldn't be triggered from a kfree(). However once struct slab stop overlaying struct page/folio then we simply can't have this validation via page/folio flag anymore, so it's fine to remove it. Maybe there will be a different way to reintroduce something similar in the memdesc world.