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Mon, 9 Feb 2026 19:03:10 +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 WShULW4vimnsTQAAD6G6ig (envelope-from ); Mon, 09 Feb 2026 19:03:10 +0000 Message-ID: Date: Mon, 9 Feb 2026 20:03:10 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] mm/slab: fix lockdep warnings with kmalloc_nolock() Content-Language: en-US To: Harry Yoo , Andrew Morton Cc: Christoph Lameter , David Rientjes , Roman Gushchin , Alexei Starovoitov , Hao Li , linux-mm@kvack.org References: <20260206171348.35886-1-harry.yoo@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: rspam11 X-Stat-Signature: rmrrk8jx3xs1zbxuaskcmxkt3oq1tbgd X-Rspam-User: X-Rspamd-Queue-Id: 0BC83120006 X-HE-Tag: 1770663792-623870 X-HE-Meta: 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 Nk1JcJ5v ovsfO+oEBwyVxUTG9JaT3Bgwq8nBlDrjKTLNcjugyEmwKuM8mw23tC/naaf0+rC15XeUVsSvAy80uJWBZeZ7PrymfjnLxm9Vc45dwZgdH/hT+Py1Nt/fEhqUI3PaDiigjUE99zI5rj+fevD4uppSgjzWRIdRGleXhaKBXVUF4ip4Hqw0Zt+UvZLGK7Hkxxzo4bwTTE+n/IzrzTfJcu/5h1lP6dy2DyUxjAzhTrMo+S+LZsUYqOXjiqs66f5vtHfmZdljC/TpPSf7qerr+qdnk57ZlybtfcwHAg+HCgc29BgRHCkoCRTNSad8ymvu78UVXRkqRhCVeJr+N148= 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 2/6/26 18:37, Harry Yoo wrote: > On Sat, Feb 07, 2026 at 02:13:46AM +0900, Harry Yoo wrote: >> Hi, I've observed a tw lockdep warnings while testing >> kmalloc_nolock() in NMI: >> >> 1. Accessing current->mems_allowed_seq seqlock in NMI isn't safe >> and lockdep complains. >> >> 2. w/ CONFIG_SLAB_FREELIST_RANDOM, get_random_u32() acquires >> a local_lock, which isn't safe in NMI and could cause a deadlock. >> >> Let's fix them. > > I think we should probably add some sort of > kmalloc_nolock()/kfree_nolock() test cases in lib/tests/slub_kunit.c. That would be useful, yes! > These haven't been discovered by bots because (I guess) it is very > unlikely for bots to somehow trigger those APIs in NMI. > > Also, I forgot to mention that this is based on slab/for-next: > > commit bc33906024eb5955294e28128c3d0f492d2ded5e > Merge: ec15c383fcda 40fd0acc45d0 > Author: Vlastimil Babka > Date: Thu Jan 29 10:10:50 2026 +0100 > > Merge branch 'slab/for-7.0/sheaves' into slab/for-next > >> Harry Yoo (2): >> mm/slab: skip get_from_any_partial() if !allow_spin >> mm/slab: use prandom if !allow_spin >> >> mm/slub.c | 36 ++++++++++++++++++++++++++++++++---- >> 1 file changed, 32 insertions(+), 4 deletions(-) >> >> -- >> 2.43.0 >> >