From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f79.google.com (mail-oo1-f79.google.com [209.85.161.79]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8763A372ED7 for ; Mon, 16 Mar 2026 10:33:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.79 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773657209; cv=none; b=cFvr9+54dC7g4JkWbTHKKyxNpr4pdPi4bzYqWs29Ekg/1vsvtwNNFnZGXuo7pVem8ILuZ7RDJi2teZiOKdrpSd+od59qMDRExEKgZrUyW8/yhc62Rf97GqNpS8Bxf5wP+ETZ3JsUa7BRr/KtvAduQtCci8AVw8PspIpDoer7s4o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773657209; c=relaxed/simple; bh=PCZPZ3Yf+Ki/Ei/bfPQrImByvPdz7ezwWX1QcI4TDCY=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=FV9owNazCDhd15n26WMk71r44x3j49PzEts4Z0YSdfc0ai/nMNsImC95P1/Sw3n1Oeo2in/VrLxGG9I3rL/I7vTVg4opO7HlY2pY/pB+EV0jQDbMTTPqrb6ldai+POURloECJtKFJ7wMepenluxSKIBKg52mewB3HIDz6VJu7s8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.161.79 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oo1-f79.google.com with SMTP id 006d021491bc7-67bd1b31789so38482630eaf.0 for ; Mon, 16 Mar 2026 03:33:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1773657206; x=1774262006; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=/uSFtZw3QSfsw1msVIIPfRGGPvw4aJjfI69zgTTRxxY=; b=Zt/jRwdDLD6in36mk8dwcf/q2W46RJCOAi1MiF0IjJ2FWKBD1v6wo3LtxaAbigTl5M /t/q20qf29itmYo4L+T1KGIbINMd5DAvt1+a9LH93lzQbrWqDBqP1ORe6J7jVZKqlR69 1Mn8MMfNIRC80PjXp4EF6ndz83OrPXEejiSxJqwRzkINjlPl+mfOOIpndjTDc4xH5spE YFDPJt/W4gHGCoD2s8HVQWLx/iSuKzXx5/v3pd80MSccnjl1BKiL6XXX+rvVBoUvrDbY KXCqS3i62JJ/cBaDmlDX304LYPx+TXmjoKhzRitYkEh11hHdGrF2+U+UozNhRRxdGMo4 EggA== X-Forwarded-Encrypted: i=1; AJvYcCURHD+jBCD6Z61tDiJ3PSDlJjIe2nq/m6emjZDeAPwnHiG1Kq8y55sQOj5zopA98yhBg/+fbQc=@vger.kernel.org X-Gm-Message-State: AOJu0YynJj0Ce6CZXMIfjlF5JUYqPVCHkKtmG/vM02Cf67vPjXxgrK0A kZFcHGqbh8PIFU5ZC9AqvC4BdfCm89NCJlhOA1f7f0AwlIu0ssT+UYNjitrQhx4Gk4twlWsgNhq SraUq2W9ORiR58MnV87RdqDHWgTX12xm2tU233HsHZMTcebUTBc0omTH5+C8= Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:210a:b0:67b:c4bd:2a89 with SMTP id 006d021491bc7-67bda9b7fd5mr8519298eaf.20.1773657206507; Mon, 16 Mar 2026 03:33:26 -0700 (PDT) Date: Mon, 16 Mar 2026 03:33:26 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69b7dc76.050a0220.248e02.0113.GAE@google.com> Subject: [syzbot] [net?] possible deadlock in __ipv6_dev_mc_inc From: syzbot To: davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 80234b5ab240 Merge tag 'rproc-v7.0-fixes' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10f4cd52580000 kernel config: https://syzkaller.appspot.com/x/.config?x=976ba5a93c4add9e dashboard link: https://syzkaller.appspot.com/bug?extid=afbcf622635e98bf40d2 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/2e6b301fd0a3/disk-80234b5a.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/b7beeadf358c/vmlinux-80234b5a.xz kernel image: https://storage.googleapis.com/syzbot-assets/0570bee580ee/bzImage-80234b5a.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+afbcf622635e98bf40d2@syzkaller.appspotmail.com netlink: 132 bytes leftover after parsing attributes in process `syz.2.4459'. ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.2.4459/20989 is trying to acquire lock: ffffffff8e9ab040 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:317 [inline] ffffffff8e9ab040 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:4493 [inline] ffffffff8e9ab040 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4846 [inline] ffffffff8e9ab040 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_cache_noprof+0x4b/0x6f0 mm/slub.c:5378 but task is already holding lock: ffff88803538d538 (&idev->mc_lock){+.+.}-{4:4}, at: __ipv6_dev_mc_inc+0x53/0xbc0 net/ipv6/mcast.c:943 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #7 (&idev->mc_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 __ipv6_dev_mc_inc+0x53/0xbc0 net/ipv6/mcast.c:943 __ipv6_sock_mc_join+0x5b8/0x8e0 net/ipv6/mcast.c:234 do_ipv6_mcast_group_source+0x21e/0x270 net/ipv6/ipv6_sockglue.c:173 do_ipv6_setsockopt+0x1fe3/0x4510 net/ipv6/ipv6_sockglue.c:919 ipv6_setsockopt+0xcb/0x170 net/ipv6/ipv6_sockglue.c:973 udpv6_setsockopt+0x7d/0xd0 net/ipv6/udp.c:1846 do_sock_setsockopt+0xf3/0x1d0 net/socket.c:2322 __sys_setsockopt+0x195/0x220 net/socket.c:2347 __do_sys_setsockopt net/socket.c:2353 [inline] __se_sys_setsockopt net/socket.c:2350 [inline] __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2350 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #6 (sk_lock-AF_INET6){+.+.}-{0:0}: lock_sock_nested+0x41/0xf0 net/core/sock.c:3780 lock_sock include/net/sock.h:1709 [inline] inet_shutdown+0x67/0x410 net/ipv4/af_inet.c:913 nbd_mark_nsock_dead+0xae/0x5c0 drivers/block/nbd.c:318 recv_work+0x5fb/0x8c0 drivers/block/nbd.c:1021 process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275 process_scheduled_works kernel/workqueue.c:3358 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3439 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #5 (&nsock->tx_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 nbd_handle_cmd drivers/block/nbd.c:1143 [inline] nbd_queue_rq+0x428/0x1080 drivers/block/nbd.c:1207 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148 __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+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753 submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821 submit_bh fs/buffer.c:2826 [inline] block_read_full_folio+0x264/0x8e0 fs/buffer.c:2444 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4101 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:723 adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694 blkdev_get_whole+0x187/0x290 block/bdev.c:764 bdev_open+0x2c7/0xe40 block/bdev.c:973 blkdev_open+0x34e/0x4f0 block/fops.c:697 do_dentry_open+0x6d8/0x1660 fs/open.c:949 vfs_open+0x82/0x3f0 fs/open.c:1081 do_open fs/namei.c:4671 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4830 do_file_open+0x20e/0x430 fs/namei.c:4859 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&cmd->lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 nbd_queue_rq+0xba/0x1080 drivers/block/nbd.c:1199 blk_mq_dispatch_rq_list+0x422/0x1e70 block/blk-mq.c:2148 __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+0xcea/0x1620 block/blk-mq-sched.c:307 blk_mq_sched_dispatch_requests+0xd7/0x1c0 block/blk-mq-sched.c:329 blk_mq_run_hw_queue+0x23c/0x670 block/blk-mq.c:2386 blk_mq_dispatch_list+0x51d/0x1360 block/blk-mq.c:2949 blk_mq_flush_plug_list block/blk-mq.c:2997 [inline] blk_mq_flush_plug_list+0x130/0x600 block/blk-mq.c:2969 __blk_flush_plug+0x2c4/0x4b0 block/blk-core.c:1230 blk_finish_plug block/blk-core.c:1257 [inline] __submit_bio+0x584/0x6c0 block/blk-core.c:649 __submit_bio_noacct_mq block/blk-core.c:722 [inline] submit_bio_noacct_nocheck+0x562/0xc10 block/blk-core.c:753 submit_bio_noacct+0xd17/0x2010 block/blk-core.c:884 blk_crypto_submit_bio include/linux/blk-crypto.h:203 [inline] submit_bh_wbc+0x59c/0x770 fs/buffer.c:2821 submit_bh fs/buffer.c:2826 [inline] block_read_full_folio+0x264/0x8e0 fs/buffer.c:2444 filemap_read_folio+0xfc/0x3b0 mm/filemap.c:2501 do_read_cache_folio+0x2d7/0x6b0 mm/filemap.c:4101 read_mapping_folio include/linux/pagemap.h:1028 [inline] read_part_sector+0xd1/0x370 block/partitions/core.c:723 adfspart_check_ICS+0x93/0x910 block/partitions/acorn.c:360 check_partition block/partitions/core.c:142 [inline] blk_add_partitions block/partitions/core.c:590 [inline] bdev_disk_changed+0x7f8/0xc80 block/partitions/core.c:694 blkdev_get_whole+0x187/0x290 block/bdev.c:764 bdev_open+0x2c7/0xe40 block/bdev.c:973 blkdev_open+0x34e/0x4f0 block/fops.c:697 do_dentry_open+0x6d8/0x1660 fs/open.c:949 vfs_open+0x82/0x3f0 fs/open.c:1081 do_open fs/namei.c:4671 [inline] path_openat+0x208c/0x31a0 fs/namei.c:4830 do_file_open+0x20e/0x430 fs/namei.c:4859 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1383 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (set->srcu){.+.+}-{0:0}: srcu_lock_sync include/linux/srcu.h:199 [inline] __synchronize_srcu+0xa1/0x2a0 kernel/rcu/srcutree.c:1505 blk_mq_wait_quiesce_done block/blk-mq.c:284 [inline] blk_mq_wait_quiesce_done block/blk-mq.c:281 [inline] blk_mq_quiesce_queue block/blk-mq.c:304 [inline] blk_mq_quiesce_queue+0x149/0x1c0 block/blk-mq.c:299 elevator_switch+0x17b/0x7e0 block/elevator.c:576 elevator_change+0x352/0x530 block/elevator.c:681 elevator_set_default+0x29e/0x360 block/elevator.c:754 blk_register_queue+0x412/0x590 block/blk-sysfs.c:946 __add_disk+0x73f/0xe40 block/genhd.c:528 add_disk_fwnode+0x118/0x5c0 block/genhd.c:597 add_disk include/linux/blkdev.h:785 [inline] nbd_dev_add+0x77a/0xb10 drivers/block/nbd.c:1984 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692 do_one_initcall+0x11d/0x760 init/main.c:1382 do_initcall_level init/main.c:1444 [inline] do_initcalls init/main.c:1460 [inline] do_basic_setup init/main.c:1479 [inline] kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692 kernel_init+0x1f/0x1e0 init/main.c:1582 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (&q->elevator_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 elevator_change+0x1bc/0x530 block/elevator.c:679 elevator_set_none+0x92/0xf0 block/elevator.c:769 blk_mq_elv_switch_none block/blk-mq.c:5110 [inline] __blk_mq_update_nr_hw_queues block/blk-mq.c:5155 [inline] blk_mq_update_nr_hw_queues+0x4c1/0x15f0 block/blk-mq.c:5220 nbd_start_device+0x1a6/0xbd0 drivers/block/nbd.c:1489 nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline] __nbd_ioctl drivers/block/nbd.c:1623 [inline] nbd_ioctl+0x4a6/0xd30 drivers/block/nbd.c:1663 blkdev_ioctl+0x5ad/0x6f0 block/ioctl.c:804 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&q->q_usage_counter(io)#53){++++}-{0:0}: blk_alloc_queue+0x610/0x790 block/blk-core.c:461 blk_mq_alloc_queue+0x174/0x290 block/blk-mq.c:4429 __blk_mq_alloc_disk+0x29/0x120 block/blk-mq.c:4476 nbd_dev_add+0x492/0xb10 drivers/block/nbd.c:1954 nbd_init+0x291/0x2b0 drivers/block/nbd.c:2692 do_one_initcall+0x11d/0x760 init/main.c:1382 do_initcall_level init/main.c:1444 [inline] do_initcalls init/main.c:1460 [inline] do_basic_setup init/main.c:1479 [inline] kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692 kernel_init+0x1f/0x1e0 init/main.c:1582 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (fs_reclaim){+.+.}-{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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4348 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4362 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4493 [inline] slab_alloc_node mm/slub.c:4846 [inline] __kmalloc_cache_noprof+0x4b/0x6f0 mm/slub.c:5378 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] mca_alloc net/ipv6/mcast.c:871 [inline] __ipv6_dev_mc_inc+0x2f1/0xbc0 net/ipv6/mcast.c:961 pndisc_constructor+0xf7/0x150 net/ipv6/ndisc.c:383 pneigh_create+0x2ae/0x4f0 net/core/neighbour.c:810 neigh_add+0x458/0x1210 net/core/neighbour.c:2088 rtnetlink_rcv_msg+0x3c9/0xe90 net/core/rtnetlink.c:6967 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2592 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2646 __sys_sendmsg+0x170/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: fs_reclaim --> sk_lock-AF_INET6 --> &idev->mc_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&idev->mc_lock); lock(sk_lock-AF_INET6); lock(&idev->mc_lock); lock(fs_reclaim); *** DEADLOCK *** 3 locks held by syz.2.4459/20989: #0: ffffffff90610828 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff90610828 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x371/0xe90 net/core/rtnetlink.c:6964 #1: ffffffff908161a0 (&tbl->phash_lock){+.+.}-{4:4}, at: pneigh_create+0x46/0x4f0 net/core/neighbour.c:792 #2: ffff88803538d538 (&idev->mc_lock){+.+.}-{4:4}, at: __ipv6_dev_mc_inc+0x53/0xbc0 net/ipv6/mcast.c:943 stack backtrace: CPU: 0 UID: 0 PID: 20989 Comm: syz.2.4459 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175 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+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1cf/0x380 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:4348 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4362 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4493 [inline] slab_alloc_node mm/slub.c:4846 [inline] __kmalloc_cache_noprof+0x4b/0x6f0 mm/slub.c:5378 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] mca_alloc net/ipv6/mcast.c:871 [inline] __ipv6_dev_mc_inc+0x2f1/0xbc0 net/ipv6/mcast.c:961 pndisc_constructor+0xf7/0x150 net/ipv6/ndisc.c:383 pneigh_create+0x2ae/0x4f0 net/core/neighbour.c:810 neigh_add+0x458/0x1210 net/core/neighbour.c:2088 rtnetlink_rcv_msg+0x3c9/0xe90 net/core/rtnetlink.c:6967 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5aa/0x870 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2592 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2646 __sys_sendmsg+0x170/0x220 net/socket.c:2678 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f26f559c799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f26f650a028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f26f5816090 RCX: 00007f26f559c799 RDX: 0000000000040094 RSI: 0000200000000100 RDI: 0000000000000005 RBP: 00007f26f5632c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f26f5816128 R14: 00007f26f5816090 R15: 00007fffe7ac39c8 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup