From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9CA6F2FA0F2; Fri, 14 Nov 2025 10:27:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763116069; cv=none; b=jJCfjPtlWeId2GJYxSGs+X3HJ/W0BVt6b+zu7rBjcola0ZZIvLe9XYLtarGCJyuEqyW6mxKR21FpMbBgCWJ3IrXt729InmnrOo0ZyW8xr5K1gG8Vy70DMptSIetYVqfhhNhsSWMxQGS8gFUdJjBfCUM1KhtnhSu1W3TYvcmJs3w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763116069; c=relaxed/simple; bh=RTmM7fTyjP3bs7vHWQ8OBVi7VJf0cvB7mMLlycA2/pA=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=jvpasJajKUllwPXZWKx7fxrcQPcGQqLuVRfRhmdxGTn51IegRZ10vaBIc26S2agmWJmacCVfZ5YghHhAppvkiNjoSoE8pCsqQjjlOfzLWK19QAsdN9DL9FrgFYwUCatj/PwaSlFmLD/GhR8bai9Q3DRNHHW+MfoY+sCzzs5DTuE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZGwDgGsH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZGwDgGsH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B66AC4CEF8; Fri, 14 Nov 2025 10:27:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763116068; bh=RTmM7fTyjP3bs7vHWQ8OBVi7VJf0cvB7mMLlycA2/pA=; h=Date:Subject:To:References:From:In-Reply-To:From; b=ZGwDgGsHjSkuEz1nSvpvShkL8AE0ZEuVF+riBw1wLWm+BTUftbAfQhaKvUTVqY6sQ 4qbhTuwazN+XxSd8OhDf5zVnM0TfHAWXOMXkOs1rdX5n3pcRWYOpcVwuMYbb8zHcJg aCPwHw0v8OcuEMOWneGU5A5zy1P6WkEeJZcqDL+Wn+oLk/5JgucaGuY7NQAk7c6RZP yJ+QEsmMN2aFReN3mgBoF/UtYyaQH+Nb4qW79WGt1nf4kCH21H3yGm0+OWCQDXqdyk innlrh/NIBZnhRbdDMTbMHHsIp+beYK/BMo8gFqsr36adnd+TCzoCvX2lL6ExcaVAh /HzWiEGSB9A0g== Message-ID: <8cda478a-c589-490f-8c34-38655a6c367d@kernel.org> Date: Fri, 14 Nov 2025 11:27:42 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [mptcp?] possible deadlock in mptcp_subflow_shutdown (2) Content-Language: en-GB, fr-BE To: Paolo Abeni , syzbot , davem@davemloft.net, edumazet@google.com, geliang@kernel.org, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, martineau@kernel.org, mptcp@lists.linux.dev, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com References: <69113ffc.a70a0220.22f260.00cd.GAE@google.com> <327bfa84-c39c-4f6c-aaed-d9054f5d9ae6@redhat.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 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Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== Organization: NGI0 Core In-Reply-To: <327bfa84-c39c-4f6c-aaed-d9054f5d9ae6@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hello, On 10/11/2025 09:41, Paolo Abeni wrote: > On 11/10/25 2:29 AM, syzbot wrote: >> syzbot found the following issue on: >> >> HEAD commit: dc77806cf3b4 Merge tag 'rust-fixes-6.18' of git://git.kern.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=17dd9bcd980000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=19d831c6d0386a9c >> dashboard link: https://syzkaller.appspot.com/bug?extid=7902f127c28c701e913f >> compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 >> >> Unfortunately, I don't have any reproducer for this issue yet. >> >> Downloadable assets: >> disk image: https://storage.googleapis.com/syzbot-assets/a1c9259ca92c/disk-dc77806c.raw.xz >> vmlinux: https://storage.googleapis.com/syzbot-assets/98d084f2ad8b/vmlinux-dc77806c.xz >> kernel image: https://storage.googleapis.com/syzbot-assets/c25e628e3491/bzImage-dc77806c.xz >> >> IMPORTANT: if you fix the issue, please add the following tag to the commit: >> Reported-by: syzbot+7902f127c28c701e913f@syzkaller.appspotmail.com >> >> ====================================================== >> WARNING: possible circular locking dependency detected >> syzkaller #0 Not tainted >> ------------------------------------------------------ >> syz.7.3695/23717 is trying to acquire lock: >> ffff888087316860 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1679 [inline] >> ffff888087316860 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_subflow_shutdown+0x24/0x380 net/mptcp/protocol.c:2918 >> >> but task is already holding lock: >> ffff888026899a60 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1679 [inline] >> ffff888026899a60 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_close+0x1d/0xe0 net/mptcp/protocol.c:3168 >> >> which lock already depends on the new lock. >> >> >> the existing dependency chain (in reverse order) is: >> >> -> #7 (sk_lock-AF_INET){+.+.}-{0:0}: >> lock_sock_nested+0x41/0xf0 net/core/sock.c:3720 >> lock_sock include/net/sock.h:1679 [inline] >> inet_shutdown+0x67/0x440 net/ipv4/af_inet.c:907 >> nbd_mark_nsock_dead+0xae/0x5d0 drivers/block/nbd.c:319 >> recv_work+0x671/0xa80 drivers/block/nbd.c:1024 >> process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263 >> process_scheduled_works kernel/workqueue.c:3346 [inline] >> worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427 >> kthread+0x3c5/0x780 kernel/kthread.c:463 >> ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 >> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 >> >> -> #6 (&nsock->tx_lock){+.+.}-{4:4}: >> __mutex_lock_common kernel/locking/mutex.c:598 [inline] >> __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 >> nbd_handle_cmd drivers/block/nbd.c:1146 [inline] >> nbd_queue_rq+0x423/0x12d0 drivers/block/nbd.c:1210 >> blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2129 >> __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] >> blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] >> __blk_mq_sched_dispatch_requests+0xcb7/0x15f0 block/blk-mq-sched.c:307 >> blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329 >> blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2367 >> blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2928 >> blk_mq_flush_plug_list block/blk-mq.c:2976 [inline] >> blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2948 >> __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225 >> blk_finish_plug block/blk-core.c:1252 [inline] >> blk_finish_plug block/blk-core.c:1249 [inline] >> __submit_bio+0x545/0x690 block/blk-core.c:651 >> __submit_bio_noacct_mq block/blk-core.c:724 [inline] >> submit_bio_noacct_nocheck+0x53d/0xc10 block/blk-core.c:755 >> submit_bio_noacct+0x5bd/0x1f60 block/blk-core.c:879 >> submit_bh fs/buffer.c:2829 [inline] >> block_read_full_folio+0x4db/0x850 fs/buffer.c:2461 >> filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2444 >> do_read_cache_folio+0x263/0x5c0 mm/filemap.c:4024 >> read_mapping_folio include/linux/pagemap.h:999 [inline] >> read_part_sector+0xd4/0x370 block/partitions/core.c:722 >> adfspart_check_ICS+0x93/0x940 block/partitions/acorn.c:360 >> check_partition block/partitions/core.c:141 [inline] >> blk_add_partitions block/partitions/core.c:589 [inline] >> bdev_disk_changed+0x723/0x1520 block/partitions/core.c:693 >> blkdev_get_whole+0x187/0x290 block/bdev.c:748 >> bdev_open+0x2c7/0xe40 block/bdev.c:957 >> blkdev_open+0x34e/0x4f0 block/fops.c:701 >> do_dentry_open+0x982/0x1530 fs/open.c:965 >> vfs_open+0x82/0x3f0 fs/open.c:1097 >> do_open fs/namei.c:3975 [inline] >> path_openat+0x1de4/0x2cb0 fs/namei.c:4134 >> do_filp_open+0x20b/0x470 fs/namei.c:4161 >> do_sys_openat2+0x11b/0x1d0 fs/open.c:1437 >> do_sys_open fs/open.c:1452 [inline] >> __do_sys_openat fs/open.c:1468 [inline] >> __se_sys_openat fs/open.c:1463 [inline] >> __x64_sys_openat+0x174/0x210 fs/open.c:1463 >> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] >> do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 >> entry_SYSCALL_64_after_hwframe+0x77/0x7f >> >> -> #5 (&cmd->lock){+.+.}-{4:4}: >> __mutex_lock_common kernel/locking/mutex.c:598 [inline] >> __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 >> nbd_queue_rq+0xbd/0x12d0 drivers/block/nbd.c:1202 >> blk_mq_dispatch_rq_list+0x416/0x1e20 block/blk-mq.c:2129 >> __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline] >> blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline] >> __blk_mq_sched_dispatch_requests+0xcb7/0x15f0 block/blk-mq-sched.c:307 >> blk_mq_sched_dispatch_requests+0xd8/0x1b0 block/blk-mq-sched.c:329 >> blk_mq_run_hw_queue+0x239/0x670 block/blk-mq.c:2367 >> blk_mq_dispatch_list+0x514/0x1310 block/blk-mq.c:2928 >> blk_mq_flush_plug_list block/blk-mq.c:2976 [inline] >> blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2948 >> __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1225 >> blk_finish_plug block/blk-core.c:1252 [inline] >> blk_finish_plug block/blk-core.c:1249 [inline] >> __submit_bio+0x545/0x690 block/blk-core.c:651 >> __submit_bio_noacct_mq block/blk-core.c:724 [inline] >> submit_bio_noacct_nocheck+0x53d/0xc10 block/blk-core.c:755 >> submit_bio_noacct+0x5bd/0x1f60 block/blk-core.c:879 >> submit_bh fs/buffer.c:2829 [inline] >> block_read_full_folio+0x4db/0x850 fs/buffer.c:2461 >> filemap_read_folio+0xc8/0x2a0 mm/filemap.c:2444 >> do_read_cache_folio+0x263/0x5c0 mm/filemap.c:4024 >> read_mapping_folio include/linux/pagemap.h:999 [inline] >> read_part_sector+0xd4/0x370 block/partitions/core.c:722 >> adfspart_check_ICS+0x93/0x940 block/partitions/acorn.c:360 >> check_partition block/partitions/core.c:141 [inline] >> blk_add_partitions block/partitions/core.c:589 [inline] >> bdev_disk_changed+0x723/0x1520 block/partitions/core.c:693 >> blkdev_get_whole+0x187/0x290 block/bdev.c:748 >> bdev_open+0x2c7/0xe40 block/bdev.c:957 >> blkdev_open+0x34e/0x4f0 block/fops.c:701 >> do_dentry_open+0x982/0x1530 fs/open.c:965 >> vfs_open+0x82/0x3f0 fs/open.c:1097 >> do_open fs/namei.c:3975 [inline] >> path_openat+0x1de4/0x2cb0 fs/namei.c:4134 >> do_filp_open+0x20b/0x470 fs/namei.c:4161 >> do_sys_openat2+0x11b/0x1d0 fs/open.c:1437 >> do_sys_open fs/open.c:1452 [inline] >> __do_sys_openat fs/open.c:1468 [inline] >> __se_sys_openat fs/open.c:1463 [inline] >> __x64_sys_openat+0x174/0x210 fs/open.c:1463 >> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] >> do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 >> entry_SYSCALL_64_after_hwframe+0x77/0x7f >> >> -> #4 (set->srcu){.+.+}-{0:0}: >> srcu_lock_sync include/linux/srcu.h:173 [inline] >> __synchronize_srcu+0xa1/0x290 kernel/rcu/srcutree.c:1439 >> blk_mq_wait_quiesce_done block/blk-mq.c:283 [inline] >> blk_mq_wait_quiesce_done block/blk-mq.c:280 [inline] >> blk_mq_quiesce_queue block/blk-mq.c:303 [inline] >> blk_mq_quiesce_queue+0x149/0x1b0 block/blk-mq.c:298 >> elevator_switch+0x17d/0x810 block/elevator.c:588 >> elevator_change+0x391/0x5d0 block/elevator.c:691 >> elevator_set_default+0x2e9/0x380 block/elevator.c:767 >> blk_register_queue+0x384/0x4e0 block/blk-sysfs.c:942 >> __add_disk+0x74a/0xf00 block/genhd.c:528 >> add_disk_fwnode+0x13f/0x5d0 block/genhd.c:597 >> add_disk include/linux/blkdev.h:775 [inline] >> nbd_dev_add+0x783/0xbb0 drivers/block/nbd.c:1987 >> nbd_init+0x1a2/0x3c0 drivers/block/nbd.c:2702 >> do_one_initcall+0x123/0x6e0 init/main.c:1283 >> do_initcall_level init/main.c:1345 [inline] >> do_initcalls init/main.c:1361 [inline] >> do_basic_setup init/main.c:1380 [inline] >> kernel_init_freeable+0x5c8/0x920 init/main.c:1593 >> kernel_init+0x1c/0x2b0 init/main.c:1483 >> ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 >> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 >> >> -> #3 (&q->elevator_lock){+.+.}-{4:4}: >> __mutex_lock_common kernel/locking/mutex.c:598 [inline] >> __mutex_lock+0x193/0x1060 kernel/locking/mutex.c:760 >> queue_requests_store+0x3a7/0x670 block/blk-sysfs.c:117 >> queue_attr_store+0x26b/0x310 block/blk-sysfs.c:869 >> sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 >> kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352 >> new_sync_write fs/read_write.c:593 [inline] >> vfs_write+0x7d3/0x11d0 fs/read_write.c:686 >> ksys_write+0x12a/0x250 fs/read_write.c:738 >> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] >> do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 >> entry_SYSCALL_64_after_hwframe+0x77/0x7f >> >> -> #2 (&q->q_usage_counter(io)#52){++++}-{0:0}: >> blk_alloc_queue+0x619/0x760 block/blk-core.c:461 >> blk_mq_alloc_queue+0x172/0x280 block/blk-mq.c:4399 >> __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4446 >> nbd_dev_add+0x492/0xbb0 drivers/block/nbd.c:1957 >> nbd_init+0x1a2/0x3c0 drivers/block/nbd.c:2702 >> do_one_initcall+0x123/0x6e0 init/main.c:1283 >> do_initcall_level init/main.c:1345 [inline] >> do_initcalls init/main.c:1361 [inline] >> do_basic_setup init/main.c:1380 [inline] >> kernel_init_freeable+0x5c8/0x920 init/main.c:1593 >> kernel_init+0x1c/0x2b0 init/main.c:1483 >> ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 >> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 >> >> -> #1 (fs_reclaim){+.+.}-{0:0}: >> __fs_reclaim_acquire mm/page_alloc.c:4269 [inline] >> fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:4283 >> might_alloc include/linux/sched/mm.h:318 [inline] >> slab_pre_alloc_hook mm/slub.c:4921 [inline] >> slab_alloc_node mm/slub.c:5256 [inline] >> __kmalloc_cache_noprof+0x58/0x780 mm/slub.c:5758 >> kmalloc_noprof include/linux/slab.h:957 [inline] >> kzalloc_noprof include/linux/slab.h:1094 [inline] >> ref_tracker_alloc+0x18e/0x5b0 lib/ref_tracker.c:271 >> __netns_tracker_alloc include/net/net_namespace.h:362 [inline] >> netns_tracker_alloc include/net/net_namespace.h:371 [inline] >> get_net_track include/net/net_namespace.h:388 [inline] >> sk_net_refcnt_upgrade+0x141/0x1e0 net/core/sock.c:2384 >> rds_tcp_tune+0x23d/0x530 net/rds/tcp.c:507 >> rds_tcp_conn_path_connect+0x305/0x7f0 net/rds/tcp_connect.c:127 >> rds_connect_worker+0x1af/0x2c0 net/rds/threads.c:176 >> process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263 >> process_scheduled_works kernel/workqueue.c:3346 [inline] >> worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427 >> kthread+0x3c5/0x780 kernel/kthread.c:463 >> ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158 >> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 >> >> -> #0 (k-sk_lock-AF_INET){+.+.}-{0:0}: >> check_prev_add kernel/locking/lockdep.c:3165 [inline] >> check_prevs_add kernel/locking/lockdep.c:3284 [inline] >> validate_chain kernel/locking/lockdep.c:3908 [inline] >> __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5237 >> lock_acquire kernel/locking/lockdep.c:5868 [inline] >> lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 >> lock_sock_nested+0x41/0xf0 net/core/sock.c:3720 >> lock_sock include/net/sock.h:1679 [inline] >> mptcp_subflow_shutdown+0x24/0x380 net/mptcp/protocol.c:2918 >> mptcp_check_send_data_fin+0x248/0x440 net/mptcp/protocol.c:3022 >> __mptcp_close+0x90e/0xbe0 net/mptcp/protocol.c:3116 >> mptcp_close+0x28/0xe0 net/mptcp/protocol.c:3170 >> inet_release+0xed/0x200 net/ipv4/af_inet.c:437 >> __sock_release+0xb3/0x270 net/socket.c:662 >> sock_close+0x1c/0x30 net/socket.c:1455 >> __fput+0x402/0xb70 fs/file_table.c:468 >> task_work_run+0x150/0x240 kernel/task_work.c:227 >> resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] >> exit_to_user_mode_loop+0xec/0x130 kernel/entry/common.c:43 >> exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] >> syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] >> syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] >> do_syscall_64+0x426/0xfa0 arch/x86/entry/syscall_64.c:100 >> entry_SYSCALL_64_after_hwframe+0x77/0x7f >> >> other info that might help us debug this: >> >> Chain exists of: >> k-sk_lock-AF_INET --> &nsock->tx_lock --> sk_lock-AF_INET > > It looks like a false positive due to mptcp subflows and nbd connection > sockets getting the lockdep annotation. We should possibly/likely use a > specific lockdep key for mptcp subflows. As noted by Paolo offline, it looks like this issue is due to nbd introducing a lockdep dependency between reclaim and af_socket, and this is similar to a previous report: #syz dup: [syzbot] [mptcp?] possible deadlock in mptcp_subflow_create_socket (2) Cheers, Matt -- Sponsored by the NGI0 Core fund.