[syzbot] [net?] possible deadlock in genl_rcv (4)
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syzbot
9:47 AM (10 hours ago) 9:47 AM
to da...@davemloft.net, edum...@google.com, ho...@kernel.org, ku...@kernel.org, linux-...@vger.kernel.org, net...@vger.kernel.org, pab...@redhat.com, syzkall...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: c1ecb239fa34 Add linux-next specific files for 20260522
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10e1bcec580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e0299bf0261ddd5
dashboard link: https://syzkaller.appspot.com/bug?extid=c4e9d077bcc86bee08dc
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b8845b668755/disk-c1ecb239.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/517b638d908a/vmlinux-c1ecb239.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd5e3b587fce/bzImage-c1ecb239.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c4e9d0...@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G L
------------------------------------------------------
syz.3.4345/21265 is trying to acquire lock:
ffffffff8f3f0600 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
but task is already holding lock:
ffff888037262058 (&pipe->mutex){+.+.}-{4:4}, at: splice_to_socket+0x15f/0x11f0 fs/splice.c:805
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (&pipe->mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
iter_file_splice_write+0x1f3/0x10f0 fs/splice.c:682
do_splice_from fs/splice.c:936 [inline]
do_splice+0xef8/0x1940 fs/splice.c:1349
__do_splice fs/splice.c:1431 [inline]
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice+0x353/0x490 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #6 (sb_writers#5){.+.+}-{0:0}:
percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_write include/linux/fs/super.h:125 [inline]
kiocb_start_write include/linux/fs.h:2767 [inline]
lo_rw_aio+0xb1b/0xf00 drivers/block/loop.c:401
do_req_filebacked drivers/block/loop.c:433 [inline]
loop_handle_cmd drivers/block/loop.c:1941 [inline]
loop_process_work+0x637/0x11b0 drivers/block/loop.c:1976
process_one_work+0x98b/0x1630 kernel/workqueue.c:3318
process_scheduled_works kernel/workqueue.c:3401 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #5 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x8d7/0x1630 kernel/workqueue.c:3294
process_scheduled_works kernel/workqueue.c:3401 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #4 ((wq_completion)loop0){+.+.}-{0:0}:
touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:4033
__flush_workqueue+0x14b/0x14f0 kernel/workqueue.c:4075
drain_workqueue+0xd3/0x390 kernel/workqueue.c:4239
__loop_clr_fd drivers/block/loop.c:1130 [inline]
lo_release+0x287/0x8f0 drivers/block/loop.c:1767
bdev_release+0x541/0x660 block/bdev.c:-1
blkdev_release+0x15/0x20 block/fops.c:705
__fput+0x461/0xa70 fs/file_table.c:510
fput_close_sync+0x11f/0x240 fs/file_table.c:615
__do_sys_close fs/open.c:1511 [inline]
__se_sys_close fs/open.c:1496 [inline]
__x64_sys_close+0x7e/0x110 fs/open.c:1496
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (&disk->open_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
__del_gendisk+0x127/0x980 block/genhd.c:710
del_gendisk+0xe7/0x160 block/genhd.c:823
loop_remove+0x42/0xc0 drivers/block/loop.c:2136
loop_control_remove drivers/block/loop.c:2195 [inline]
loop_control_ioctl+0x4ba/0x5b0 drivers/block/loop.c:2237
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&set->update_nr_hwq_lock){++++}-{4:4}:
down_write+0x3a/0x50 kernel/locking/rwsem.c:1625
blk_mq_update_nr_hw_queues+0xbf/0x1a80 block/blk-mq.c:5242
nbd_start_device+0x17f/0xb20 drivers/block/nbd.c:1489
nbd_genl_connect+0x1651/0x1c80 drivers/block/nbd.c:2239
genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2551
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x780/0x920 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895
sock_sendmsg_nosec+0x112/0x150 net/socket.c:797
__sock_sendmsg net/socket.c:812 [inline]
____sys_sendmsg+0x55c/0x870 net/socket.c:2716
___sys_sendmsg+0x2a5/0x360 net/socket.c:2770
__sys_sendmsg net/socket.c:2802 [inline]
__do_sys_sendmsg net/socket.c:2807 [inline]
__se_sys_sendmsg net/socket.c:2805 [inline]
__x64_sys_sendmsg+0x1c3/0x2a0 net/socket.c:2805
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (genl_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
genl_lock net/netlink/genetlink.c:35 [inline]
genl_lock_all net/netlink/genetlink.c:48 [inline]
genl_register_family+0x7b9/0x17b0 net/netlink/genetlink.c:784
vdpa_init+0x39/0x70 drivers/vdpa/vdpa.c:1565
do_one_initcall+0x250/0x870 init/main.c:1347
do_initcall_level+0x104/0x190 init/main.c:1409
do_initcalls+0x59/0xa0 init/main.c:1425
kernel_init_freeable+0x2a6/0x3e0 init/main.c:1658
kernel_init+0x1d/0x1d0 init/main.c:1548
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #0 (cb_lock){++++}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3167 [inline]
check_prevs_add kernel/locking/lockdep.c:3286 [inline]
validate_chain kernel/locking/lockdep.c:3910 [inline]
__lock_acquire+0x15a5/0x2d10 kernel/locking/lockdep.c:5239
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
down_read+0x97/0x200 kernel/locking/rwsem.c:1568
genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x780/0x920 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895
sock_sendmsg_nosec+0x112/0x150 net/socket.c:797
__sock_sendmsg net/socket.c:812 [inline]
sock_sendmsg+0x1ca/0x2d0 net/socket.c:835
splice_to_socket+0xae5/0x11f0 fs/splice.c:884
do_splice_from fs/splice.c:936 [inline]
do_splice+0xef8/0x1940 fs/splice.c:1349
__do_splice fs/splice.c:1431 [inline]
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice+0x353/0x490 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 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:
cb_lock --> sb_writers#5 --> &pipe->mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&pipe->mutex);
lock(sb_writers#5);
lock(&pipe->mutex);
rlock(cb_lock);
*** DEADLOCK ***
1 lock held by syz.3.4345/21265:
#0: ffff888037262058 (&pipe->mutex){+.+.}-{4:4}, at: splice_to_socket+0x15f/0x11f0 fs/splice.c:805
stack backtrace:
CPU: 1 UID: 0 PID: 21265 Comm: syz.3.4345 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2045
check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3167 [inline]
check_prevs_add kernel/locking/lockdep.c:3286 [inline]
validate_chain kernel/locking/lockdep.c:3910 [inline]
__lock_acquire+0x15a5/0x2d10 kernel/locking/lockdep.c:5239
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
down_read+0x97/0x200 kernel/locking/rwsem.c:1568
genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x780/0x920 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895
sock_sendmsg_nosec+0x112/0x150 net/socket.c:797
__sock_sendmsg net/socket.c:812 [inline]
sock_sendmsg+0x1ca/0x2d0 net/socket.c:835
splice_to_socket+0xae5/0x11f0 fs/splice.c:884
do_splice_from fs/splice.c:936 [inline]
do_splice+0xef8/0x1940 fs/splice.c:1349
__do_splice fs/splice.c:1431 [inline]
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice+0x353/0x490 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f599bdfce59
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:00007f599a035028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f599c076090 RCX: 00007f599bdfce59
RDX: 0000000000000007 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f599be92d6f R08: 000000000004ffe2 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f599c076128 R14: 00007f599c076090 R15: 00007ffe56c36778
</TASK>
---
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syzbot found the following issue on:
HEAD commit: c1ecb239fa34 Add linux-next specific files for 20260522
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10e1bcec580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e0299bf0261ddd5
dashboard link: https://syzkaller.appspot.com/bug?extid=c4e9d077bcc86bee08dc
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b8845b668755/disk-c1ecb239.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/517b638d908a/vmlinux-c1ecb239.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd5e3b587fce/bzImage-c1ecb239.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c4e9d0...@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G L
------------------------------------------------------
syz.3.4345/21265 is trying to acquire lock:
ffffffff8f3f0600 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
but task is already holding lock:
ffff888037262058 (&pipe->mutex){+.+.}-{4:4}, at: splice_to_socket+0x15f/0x11f0 fs/splice.c:805
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (&pipe->mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
iter_file_splice_write+0x1f3/0x10f0 fs/splice.c:682
do_splice_from fs/splice.c:936 [inline]
do_splice+0xef8/0x1940 fs/splice.c:1349
__do_splice fs/splice.c:1431 [inline]
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice+0x353/0x490 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #6 (sb_writers#5){.+.+}-{0:0}:
percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_write include/linux/fs/super.h:125 [inline]
kiocb_start_write include/linux/fs.h:2767 [inline]
lo_rw_aio+0xb1b/0xf00 drivers/block/loop.c:401
do_req_filebacked drivers/block/loop.c:433 [inline]
loop_handle_cmd drivers/block/loop.c:1941 [inline]
loop_process_work+0x637/0x11b0 drivers/block/loop.c:1976
process_one_work+0x98b/0x1630 kernel/workqueue.c:3318
process_scheduled_works kernel/workqueue.c:3401 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #5 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x8d7/0x1630 kernel/workqueue.c:3294
process_scheduled_works kernel/workqueue.c:3401 [inline]
worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #4 ((wq_completion)loop0){+.+.}-{0:0}:
touch_wq_lockdep_map+0xcb/0x180 kernel/workqueue.c:4033
__flush_workqueue+0x14b/0x14f0 kernel/workqueue.c:4075
drain_workqueue+0xd3/0x390 kernel/workqueue.c:4239
__loop_clr_fd drivers/block/loop.c:1130 [inline]
lo_release+0x287/0x8f0 drivers/block/loop.c:1767
bdev_release+0x541/0x660 block/bdev.c:-1
blkdev_release+0x15/0x20 block/fops.c:705
__fput+0x461/0xa70 fs/file_table.c:510
fput_close_sync+0x11f/0x240 fs/file_table.c:615
__do_sys_close fs/open.c:1511 [inline]
__se_sys_close fs/open.c:1496 [inline]
__x64_sys_close+0x7e/0x110 fs/open.c:1496
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #3 (&disk->open_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
__del_gendisk+0x127/0x980 block/genhd.c:710
del_gendisk+0xe7/0x160 block/genhd.c:823
loop_remove+0x42/0xc0 drivers/block/loop.c:2136
loop_control_remove drivers/block/loop.c:2195 [inline]
loop_control_ioctl+0x4ba/0x5b0 drivers/block/loop.c:2237
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&set->update_nr_hwq_lock){++++}-{4:4}:
down_write+0x3a/0x50 kernel/locking/rwsem.c:1625
blk_mq_update_nr_hw_queues+0xbf/0x1a80 block/blk-mq.c:5242
nbd_start_device+0x17f/0xb20 drivers/block/nbd.c:1489
nbd_genl_connect+0x1651/0x1c80 drivers/block/nbd.c:2239
genl_family_rcv_msg_doit+0x22a/0x330 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x61c/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2551
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x780/0x920 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895
sock_sendmsg_nosec+0x112/0x150 net/socket.c:797
__sock_sendmsg net/socket.c:812 [inline]
____sys_sendmsg+0x55c/0x870 net/socket.c:2716
___sys_sendmsg+0x2a5/0x360 net/socket.c:2770
__sys_sendmsg net/socket.c:2802 [inline]
__do_sys_sendmsg net/socket.c:2807 [inline]
__se_sys_sendmsg net/socket.c:2805 [inline]
__x64_sys_sendmsg+0x1c3/0x2a0 net/socket.c:2805
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (genl_mutex){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline]
mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578
genl_lock net/netlink/genetlink.c:35 [inline]
genl_lock_all net/netlink/genetlink.c:48 [inline]
genl_register_family+0x7b9/0x17b0 net/netlink/genetlink.c:784
vdpa_init+0x39/0x70 drivers/vdpa/vdpa.c:1565
do_one_initcall+0x250/0x870 init/main.c:1347
do_initcall_level+0x104/0x190 init/main.c:1409
do_initcalls+0x59/0xa0 init/main.c:1425
kernel_init_freeable+0x2a6/0x3e0 init/main.c:1658
kernel_init+0x1d/0x1d0 init/main.c:1548
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #0 (cb_lock){++++}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3167 [inline]
check_prevs_add kernel/locking/lockdep.c:3286 [inline]
validate_chain kernel/locking/lockdep.c:3910 [inline]
__lock_acquire+0x15a5/0x2d10 kernel/locking/lockdep.c:5239
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
down_read+0x97/0x200 kernel/locking/rwsem.c:1568
genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x780/0x920 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895
sock_sendmsg_nosec+0x112/0x150 net/socket.c:797
__sock_sendmsg net/socket.c:812 [inline]
sock_sendmsg+0x1ca/0x2d0 net/socket.c:835
splice_to_socket+0xae5/0x11f0 fs/splice.c:884
do_splice_from fs/splice.c:936 [inline]
do_splice+0xef8/0x1940 fs/splice.c:1349
__do_splice fs/splice.c:1431 [inline]
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice+0x353/0x490 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 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:
cb_lock --> sb_writers#5 --> &pipe->mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&pipe->mutex);
lock(sb_writers#5);
lock(&pipe->mutex);
rlock(cb_lock);
*** DEADLOCK ***
1 lock held by syz.3.4345/21265:
#0: ffff888037262058 (&pipe->mutex){+.+.}-{4:4}, at: splice_to_socket+0x15f/0x11f0 fs/splice.c:805
stack backtrace:
CPU: 1 UID: 0 PID: 21265 Comm: syz.3.4345 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2045
check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3167 [inline]
check_prevs_add kernel/locking/lockdep.c:3286 [inline]
validate_chain kernel/locking/lockdep.c:3910 [inline]
__lock_acquire+0x15a5/0x2d10 kernel/locking/lockdep.c:5239
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5870
down_read+0x97/0x200 kernel/locking/rwsem.c:1568
genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x780/0x920 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1895
sock_sendmsg_nosec+0x112/0x150 net/socket.c:797
__sock_sendmsg net/socket.c:812 [inline]
sock_sendmsg+0x1ca/0x2d0 net/socket.c:835
splice_to_socket+0xae5/0x11f0 fs/splice.c:884
do_splice_from fs/splice.c:936 [inline]
do_splice+0xef8/0x1940 fs/splice.c:1349
__do_splice fs/splice.c:1431 [inline]
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice+0x353/0x490 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0x560 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f599bdfce59
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:00007f599a035028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f599c076090 RCX: 00007f599bdfce59
RDX: 0000000000000007 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f599be92d6f R08: 000000000004ffe2 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f599c076128 R14: 00007f599c076090 R15: 00007ffe56c36778
</TASK>
---
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