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Fri, 14 Nov 2025 16:51:21 +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 o1H3CwleF2khBwAAD6G6ig (envelope-from ); Fri, 14 Nov 2025 16:51:21 +0000 Message-ID: <61d451f7-a54a-4c27-afab-9ae684b4bc6b@suse.cz> Date: Fri, 14 Nov 2025 17:51:20 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/mempool: fix poisoning order>0 pages with HIGHMEM To: Christoph Hellwig Cc: Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Jens Axboe , linux-block@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel test robot References: <20251113-mempool-poison-v1-1-233b3ef984c3@suse.cz> <20251114050410.GA26404@lst.de> Content-Language: en-US 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: <20251114050410.GA26404@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 277DCC0003 X-Stat-Signature: 9kn6sakbauhtj18fydp591p4f4f98fqq X-Rspam-User: X-HE-Tag: 1763139082-709930 X-HE-Meta: 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 xW9HQjsa bjlOvBsqR1fEzml3vC3vRAg0upLy5i+gx6egQNvxHSNfAV8rRH5O9+48LlRRrhSKf7nZDZVpS6MvDhQSsmcpXCA9L0nldW7mstA4rsE41cPe6tLdoybaxEhhQzgGjJ3+pXd4MAOqobEbKNa1YGagfW4r7wKyRrvG1G3ibH22o0Sp28ERpIpqKjAYwfVtFn3/mLSeZttyYd4fFvJJqP1QurMcwoywgrwAowzwezh868niGykv6uSXSgTmL+XHUuw5uMSRkasg+TmUGHTLWY4wK0xP4j7WE/mZt+lwb 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 11/14/25 06:04, Christoph Hellwig wrote: > On Thu, Nov 13, 2025 at 07:54:35PM +0100, Vlastimil Babka wrote: >> Christoph found out this is due to the poisoning code not dealing >> properly with CONFIG_HIGHMEM because only the first page is mapped but >> then the whole potentially high-order page is accessed. >> >> This went unnoticed for years probably because nobody has yet used a >> mempool for order>0 pages before the new block code in -next. > > I did a quick audit: and bcache, dm-integrity (config dependent) and the > KASAN unit tests create page based mempools with order > 0. It looks > like none of those ever got much testing on highmem systems. Thanks, KASAN unit tests sounds like something that would have been flagged by automated testing long ago, however the mempool-specific poisoning isn't compatible with it so poison_element() and check_element() both return immediately with kasan_enabled(). bcache and dm-integrity are perhaps too complex setups for the test robots. But I'll add cc: stable then. > The fix looks good: > > Reviewed-by: Christoph Hellwig