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Tue, 24 Jun 2025 17:57:09 +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 K1NUNPXmWmj4NwAAD6G6ig (envelope-from ); Tue, 24 Jun 2025 17:57:09 +0000 Message-ID: <89491be7-a480-4692-a6cf-ec54e02eb684@suse.cz> Date: Tue, 24 Jun 2025 19:57:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 5/5] mm/madvise: eliminate very confusing manipulation of prev VMA Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: David Hildenbrand , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Jann Horn , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lance Yang , SeongJae Park , Suren Baghdasaryan References: <63d281c5df2e64225ab5b4bda398b45e22818701.1750433500.git.lorenzo.stoakes@oracle.com> 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-Server: rspam12 X-Rspamd-Queue-Id: 1063E120002 X-Stat-Signature: uqu6txznhczpon7wzx78y6hs1qbxitbz X-Rspam-User: X-HE-Tag: 1750787831-772988 X-HE-Meta: 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 tV5utEWC vgqz2iAMkKeaM3jwmojLnKulPhSM0IYiFUFKLUNWUZ0oVBVfH5UU4e2CqEVfI7N2uvWIG+bM8/N9m2IQdnub8AgHop77yMIg/bm0+HLbrpDVivqcghXhCcyMMUyNAySewM1//nDNUGzhmGvvZfXL8pr38qdUdSzvHNhfOa8VJfbLx2PG/GeeYjEw+XMqLyNPT/2X85191xfhYHsGmU/eKZTw1a82k1uy/oUBDYhkQ4PlRX+uKjSn6f+XhvS4tsatmzRzHnzIkMM8d7H3T84I1L7frOA== 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 6/24/25 15:16, Lorenzo Stoakes wrote: > Hi Andrew, > > stress-ng picked up a very subtle bug here. Please apply this fix-patch to > correct it! > > Cheers, Lorenzo > > ----8<---- > From a04de12e1deb50e708392b0e716612f26c6b386a Mon Sep 17 00:00:00 2001 > From: Lorenzo Stoakes > Date: Tue, 24 Jun 2025 14:14:19 +0100 > Subject: [PATCH] mm/madvise: fix very subtle bug > > With thanks to stress-ng --madvise :) > > vma may have been updated (in the modify call in madvise_update_vma()), so > we can't assign prev = vma, we must first reassign vma to > madv_behavior->vma to account for this, before setting prev = vma. So glad we eliminated very confusing manipulation of prev VMA :) sigh... LGTM (not worth much it seems...) > --- > mm/madvise.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 4491bf080f55..c467ee42596f 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1665,8 +1665,8 @@ int madvise_walk_vmas(struct madvise_behavior *madv_behavior) > vma = NULL; > madv_behavior->lock_dropped = false; > } else { > - prev = vma; > vma = madv_behavior->vma; > + prev = vma; > } > > if (vma && range->end < vma->vm_end) > -- > 2.50.0