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Mon, 22 Dec 2025 16:11:14 +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 I6J/AaJtSWnDFAAAD6G6ig (envelope-from ); Mon, 22 Dec 2025 16:11:14 +0000 Message-ID: <5a1721bc-e7e8-40e8-b2b9-c071d18a0112@suse.cz> Date: Mon, 22 Dec 2025 17:11:13 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [linus:master] [mm/vmalloc] a061578043: BUG:spinlock_trylock_failure_on_UP_on_CPU To: Matthew Wilcox , kernel test robot Cc: Vishal Moola , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Andrew Morton , Uladzislau Rezki , linux-mm@kvack.org, Mel Gorman References: <202512101320.e2f2dd6f-lkp@intel.com> 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: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 9wnj9cxk33i6btrron3ocejzjf9fzq7h X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1B7178000C X-Rspam-User: X-HE-Tag: 1766419876-346745 X-HE-Meta: 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 XbTTG6Ji JQ6Dz5SVgk9Ud6DGbGG/9MPFBii3iQ5if0XbQ8PHov+OXV+mKsIfubAQ+Pt3uKkJgehuPJjB1hvH+pu4/R0UMHcuF3XJb0V11iASqtCIbT4ANy13H2HALUrkqsfoGpqjhn9kFKCpkUHB7kgtMym1ApPPrbFKUcDrbVkMFVTl7+FZ5zHcAAOTPkY07e9w2WL1IbQYXfpx83U+tuWC6oqxtFE6uaPE8eOAWyvraLROk02vkl3m/YomfyJacWF1iLMDjnimU6XipP7xJlb/TwsN3Jbc5T6427CMOZJL3CdlNa6J13qzLaamxBRctbGUHvu29PlA4YVkiPFpyoqyNUyiMnUKu1DGOvriYoa3V5x/NMi75EvsVTqJ+anLvT1PK73ohs1AAgxl2cuOBznL91bmBE7FnoA== 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 12/20/25 00:37, Matthew Wilcox wrote: > On Fri, Dec 19, 2025 at 08:26:14PM +0000, Matthew Wilcox wrote: >> Now, as I recall, we are very much doing this on purpose. We decided >> not to disable interrupts at this point for improved interrupt >> latency, accepting the possibility that we'd occasionally fail >> the trylock. Except on UP that's now an assertion failure. IIRC the primary motivation wasn't irq latency, it was to avoid IPIs for remote drains. So the drain_pages_zone() can be in fact locking pcp of another cpu, and any local operations on that cpu are then supposed to fail their trylock (should be relatively rare). Disabling irqs would then make no sense for protecting other cpu. > This is stupid and wrong. If we have CONFIG_SMP=n and > CONFIG_DEBUG_SPINLOCK=n, then trylock always succeeds. And we'll end > up corrupting the data structure protected by the lock. So the warning > is real, and we need to fix this. That seems to be true and we should probably be doing spin_lock_irqsave() on UP instead of spin_lock() in drain_pages_zone() and several other places. Ideally via some wrappers like we have for the trylock operations that also do some UP-specific stuff - pcp_spin_trylock() and pcp_spin_trylock(). > With my distro hat on, I do not give two hoots. We don't ship a nosmp > kernel. I suspect all other distros (except maybe something targetting > m68k?) are in the same boat. Yeah seems the problem was introduced at 6.2 with commit 574907741599 ("mm/page_alloc: leave IRQs enabled for per-cpu page allocations") or something around that. I'm off until Jan 5th so won't be developing a fix until then, but agree it doesn't seem that urgent now.