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Mon, 9 Feb 2026 10:51:29 +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 9FilKzG8iWmPDgAAD6G6ig (envelope-from ); Mon, 09 Feb 2026 10:51:29 +0000 Message-ID: <577befda-7f41-40bf-8a44-095ae184a100@suse.cz> Date: Mon, 9 Feb 2026 11:51:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2] mm/page_alloc: skip debug_check_no_{obj,locks}_freed with FPI_TRYLOCK Content-Language: en-US To: Harry Yoo , Andrew Morton Cc: Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Alexei Starovoitov , Sebastian Andrzej Siewior , Shakeel Butt , linux-mm@kvack.org, stable@vger.kernel.org References: <20260209062639.16577-1-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: <20260209062639.16577-1-harry.yoo@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: D299D1C0009 X-Stat-Signature: f9qsuutt9nob6szubcmksac34nxt39jg X-Rspam-User: X-HE-Tag: 1770634292-93278 X-HE-Meta: U2FsdGVkX18IogfteF7S34IKqEkeHBodMrowfp9vOnrMDOId1KQAODHmFhAh3hUWRGIzCAcHhflKMIY0et6YW3u2am3EH5UpG79wurafd0PEB8vfE48TBM47liB0NVQ52c4baqluqO3SzfVkJpbA4g8fEeUPi6oKDvgm/O/AoMi1/V07+Dedg67daMMtEX0hZwQayOjqxT4e8NpZUuJnC2WIYKnfrPuKn3aSaBLQVEtrjfD4CDDMwWBiJNQ0aOw03BpIBE3Fhcl4MxPuCIF/+PF1gu+S8ov0tcy875xHmQmOBAzBVSswn/ywyNLg1rFzk52ons/Uvj4Gz2QBZTpEkdHS4FBTzRrJiBC3FOq+H3xMTz+Uy08DdNhFanzIiZjW1Nts4N9Daq+sxoujSjd2RnNqvqDVeegU9BgCPXStlELGtMLFmkYv1lzEcbq/6I7TlwGduvgkNcA+QLxmlFU+wcU3//1VuGXSw/VmN6M1zeN5LFjqH3Q3dnks/6BE956HON9TXKrsKt/Lg5z+XRSOwWbfEeXBbG0b7gzWHxAZ1HS07sVmTwr0A73a0oJD/aqk9szSBzlBiXAUQFP3XmZuUZizBKu3qrptu0JAZnUq5Wy8g2VyxTkcqAYr5MOJ3oxJyJOOGrsJta5b0c2qMXfKs+D5lUJ7ZXy4xBdnSv3+/tQ5eIEsINeZrrFD3Aye0Ru7fb4RpA2npObI8A738ukj0cF9t07HQK1BgVIH2KOKpDGuswIa949IU4yUOH3VyC1JkFydoVFofaguh+5g4sSPWyMBBqSmRiSs7SAvFPUoAunwEpRLppzD18ttqaw/dGId2a/AwjkKVrHlr+HHCrAqNmwtkwp63RWdpXHD9aSBVj+UstZ75nKzcZ5APqAbzMzOL06e1pViijSerhLg7rrooGVaQb+ALSbxKgsN64VNCMo9SfeIlJLLvWF1bOsiyRxhJxpryXKFIGGCwhz3txM /6oSRwcj VWSQqiYhmD8H0p9w9EXFE7HmyJDYzgG04iuf/9UC7MxNKUPLn8SH7Fkt9ib8KuUzGzHtc3dtANHP0HF/G2xOV2m+nB5HS19ctvWZfpn36zuUJ8zFQ5BLN85Ijj9jSmSkSINeuhEhIrBSQOVFBxsNdQA4twAbH8pzsj5bSG57HlgFVt570EhxXfMkwHJSfAu4jBVvqjJgNQjX3646wS57AR5W1f6XKJrTi7XXre+0gSWxYtZk/VREREo6LnVsU7r+xcXKA2CQJLhm88J4BMcX/1PT0XInu1LUW5W7PwF4wFIocj+FMZlidhBkicOcaY1frWm3grun34f5q+bD5Hz2KpUaj30CFmEeHLDYuKAOVFbH+Ess71I0i6J6al3E2KkzeWOKy 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 2/9/26 07:26, Harry Yoo wrote: > When CONFIG_DEBUG_OBJECTS_FREE is enabled, > debug_check_no_{obj,locks}_freed() functions are called. > > Since both of them spin on a lock, they are not safe to be called > if the FPI_TRYLOCK flag is specified. This leads to a lockdep splat: > > ================================ > WARNING: inconsistent lock state > 6.19.0-rc5-slab-for-next+ #326 Tainted: G N > -------------------------------- > inconsistent {INITIAL USE} -> {IN-NMI} usage. > kunit_try_catch/9046 [HC2[2]:SC0[0]:HE0:SE1] takes: > ffffffff84ed6bf8 (&obj_hash[i].lock){-.-.}-{2:2}, at: __debug_check_no_obj_freed+0xe0/0x300 > {INITIAL USE} state was registered at: > lock_acquire+0xd9/0x2f0 > _raw_spin_lock_irqsave+0x4c/0x80 > __debug_object_init+0x9d/0x1f0 > debug_object_init+0x34/0x50 > __init_work+0x28/0x40 > init_cgroup_housekeeping+0x151/0x210 > init_cgroup_root+0x3d/0x140 > cgroup_init_early+0x30/0x240 > start_kernel+0x3e/0xcd0 > x86_64_start_reservations+0x18/0x30 > x86_64_start_kernel+0xf3/0x140 > common_startup_64+0x13e/0x148 > irq event stamp: 2998 > hardirqs last enabled at (2997): [] exc_nmi+0x11a/0x240 > hardirqs last disabled at (2998): [] sysvec_irq_work+0x11/0x110 > softirqs last enabled at (1416): [] __irq_exit_rcu+0x132/0x1c0 > softirqs last disabled at (1303): [] __irq_exit_rcu+0x132/0x1c0 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(&obj_hash[i].lock); > > lock(&obj_hash[i].lock); > > *** DEADLOCK *** > > Rename free_pages_prepare() to __free_pages_prepare(), add an fpi_t > parameter, and skip those checks if FPI_TRYLOCK is set. To keep the > fpi_t definition in mm/page_alloc.c, add a wrapper function > free_pages_prepare() that always passes FPI_NONE and use it in > mm/compaction.c. > > Fixes: 8c57b687e833 ("mm, bpf: Introduce free_pages_nolock()") > Cc: > Signed-off-by: Harry Yoo Reviewed-by: Vlastimil Babka Thanks!