[v5.15] possible deadlock in genl_rcv
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syzbot
May 29, 2026, 12:19:33 AM (6 days ago) May 29
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 241d66fa280c Linux 5.15.208
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10c229ec580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=28ffde87cd851ffc1c52
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/d3e9d10633a1/disk-241d66fa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/beca1f713e4b/vmlinux-241d66fa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/26a15a6e1c14/bzImage-241d66fa.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+28ffde...@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.5397/23098 is trying to acquire lock:
ffffffff8d49a5f0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
but task is already holding lock:
ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:596 [inline]
ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:746
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (&pipe->mutex/1){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
iter_file_splice_write+0x1b5/0xcc0 fs/splice.c:635
do_splice_from fs/splice.c:767 [inline]
do_splice+0xe5a/0x1640 fs/splice.c:1108
__do_splice fs/splice.c:1173 [inline]
__do_sys_splice fs/splice.c:1379 [inline]
__se_sys_splice+0x34d/0x440 fs/splice.c:1361
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #6 (sb_writers#3){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1811 [inline]
sb_start_write include/linux/fs.h:1881 [inline]
file_start_write include/linux/fs.h:3043 [inline]
lo_write_bvec+0x1a0/0x780 drivers/block/loop.c:315
lo_write_simple drivers/block/loop.c:338 [inline]
do_req_filebacked drivers/block/loop.c:656 [inline]
loop_handle_cmd drivers/block/loop.c:2235 [inline]
loop_process_work+0x1b46/0x24a0 drivers/block/loop.c:2275
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
-> #5 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x7bb/0x1010 kernel/workqueue.c:2286
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
-> #4 ((null)){+.+.}-{0:0}:
flush_workqueue+0x16c/0x13d0 kernel/workqueue.c:2830
drain_workqueue+0xcf/0x380 kernel/workqueue.c:2995
destroy_workqueue+0x7b/0xb20 kernel/workqueue.c:4439
__loop_clr_fd+0x234/0xb90 drivers/block/loop.c:1384
blkdev_put_whole block/bdev.c:692 [inline]
blkdev_put+0x53f/0x7d0 block/bdev.c:957
blkdev_close+0x76/0xa0 block/fops.c:478
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #3 (&lo->lo_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_killable_nested+0x17/0x20 kernel/locking/mutex.c:758
lo_open+0x6a/0x100 drivers/block/loop.c:2056
blkdev_get_whole+0x90/0x390 block/bdev.c:669
blkdev_get_by_dev+0x2d0/0xa60 block/bdev.c:827
blkdev_open+0x12d/0x2c0 block/fops.c:466
do_dentry_open+0x7ff/0xf80 fs/open.c:826
do_open fs/namei.c:3616 [inline]
path_openat+0x26f5/0x2fa0 fs/namei.c:3750
do_filp_open+0x1e2/0x410 fs/namei.c:3777
do_sys_openat2+0x150/0x4b0 fs/open.c:1255
do_sys_open fs/open.c:1271 [inline]
__do_sys_openat fs/open.c:1287 [inline]
__se_sys_openat fs/open.c:1282 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1282
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #2 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
bd_register_pending_holders+0x33/0x310 block/holder.c:161
device_add_disk+0x5a7/0xd40 block/genhd.c:486
add_disk include/linux/genhd.h:200 [inline]
nbd_dev_add+0x757/0xb20 drivers/block/nbd.c:1786
nbd_genl_connect+0x850/0x18a0 drivers/block/nbd.c:1927
genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
genl_rcv_msg+0xcea/0xf90 net/netlink/genetlink.c:792
netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
__sys_sendmsg net/socket.c:2528 [inline]
__do_sys_sendmsg net/socket.c:2537 [inline]
__se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #1 (genl_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
genl_lock net/netlink/genetlink.c:33 [inline]
genl_lock_all net/netlink/genetlink.c:46 [inline]
genl_register_family+0x3f0/0x10f0 net/netlink/genetlink.c:393
vdpa_init+0x35/0x70 drivers/vdpa/vdpa.c:903
do_one_initcall+0x272/0x730 init/main.c:1316
do_initcall_level+0x137/0x1f0 init/main.c:1389
do_initcalls+0x4b/0x90 init/main.c:1405
kernel_init_freeable+0x3e9/0x570 init/main.c:1629
kernel_init+0x19/0x1b0 init/main.c:1520
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
-> #0 (cb_lock){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
sock_sendmsg net/socket.c:741 [inline]
kernel_sendmsg+0x234/0x350 net/socket.c:765
sock_no_sendpage+0x12a/0x1a0 net/core/sock.c:3045
kernel_sendpage+0x2cb/0x380 net/socket.c:3548
sock_sendpage+0x7a/0xb0 net/socket.c:1027
pipe_to_sendpage+0x22f/0x320 fs/splice.c:364
splice_from_pipe_feed fs/splice.c:418 [inline]
__splice_from_pipe+0x302/0x820 fs/splice.c:562
splice_from_pipe fs/splice.c:597 [inline]
generic_splice_sendpage+0x111/0x180 fs/splice.c:746
do_splice_from fs/splice.c:767 [inline]
do_splice+0xe5a/0x1640 fs/splice.c:1108
__do_splice fs/splice.c:1173 [inline]
__do_sys_splice fs/splice.c:1379 [inline]
__se_sys_splice+0x34d/0x440 fs/splice.c:1361
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
other info that might help us debug this:
Chain exists of:
cb_lock --> sb_writers#3 --> &pipe->mutex/1
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&pipe->mutex/1);
lock(sb_writers#3);
lock(&pipe->mutex/1);
lock(cb_lock);
*** DEADLOCK ***
1 lock held by syz.6.5397/23098:
#0: ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:596 [inline]
#0: ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:746
stack backtrace:
CPU: 1 PID: 23098 Comm: syz.6.5397 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
sock_sendmsg net/socket.c:741 [inline]
kernel_sendmsg+0x234/0x350 net/socket.c:765
sock_no_sendpage+0x12a/0x1a0 net/core/sock.c:3045
kernel_sendpage+0x2cb/0x380 net/socket.c:3548
sock_sendpage+0x7a/0xb0 net/socket.c:1027
pipe_to_sendpage+0x22f/0x320 fs/splice.c:364
splice_from_pipe_feed fs/splice.c:418 [inline]
__splice_from_pipe+0x302/0x820 fs/splice.c:562
splice_from_pipe fs/splice.c:597 [inline]
generic_splice_sendpage+0x111/0x180 fs/splice.c:746
do_splice_from fs/splice.c:767 [inline]
do_splice+0xe5a/0x1640 fs/splice.c:1108
__do_splice fs/splice.c:1173 [inline]
__do_sys_splice fs/splice.c:1379 [inline]
__se_sys_splice+0x34d/0x440 fs/splice.c:1361
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f81af7ace59
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:00007f81ad9e5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f81afa26090 RCX: 00007f81af7ace59
RDX: 0000000000000007 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f81af842d6f R08: 000200000000622c R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f81afa26128 R14: 00007f81afa26090 R15: 00007ffd0d9e4588
</TASK>
---
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If you want to overwrite report's subsystems, reply with:
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
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syzbot found the following issue on:
HEAD commit: 241d66fa280c Linux 5.15.208
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10c229ec580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=28ffde87cd851ffc1c52
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/d3e9d10633a1/disk-241d66fa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/beca1f713e4b/vmlinux-241d66fa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/26a15a6e1c14/bzImage-241d66fa.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+28ffde...@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.5397/23098 is trying to acquire lock:
ffffffff8d49a5f0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
but task is already holding lock:
ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:596 [inline]
ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:746
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #7 (&pipe->mutex/1){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
iter_file_splice_write+0x1b5/0xcc0 fs/splice.c:635
do_splice_from fs/splice.c:767 [inline]
do_splice+0xe5a/0x1640 fs/splice.c:1108
__do_splice fs/splice.c:1173 [inline]
__do_sys_splice fs/splice.c:1379 [inline]
__se_sys_splice+0x34d/0x440 fs/splice.c:1361
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #6 (sb_writers#3){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1811 [inline]
sb_start_write include/linux/fs.h:1881 [inline]
file_start_write include/linux/fs.h:3043 [inline]
lo_write_bvec+0x1a0/0x780 drivers/block/loop.c:315
lo_write_simple drivers/block/loop.c:338 [inline]
do_req_filebacked drivers/block/loop.c:656 [inline]
loop_handle_cmd drivers/block/loop.c:2235 [inline]
loop_process_work+0x1b46/0x24a0 drivers/block/loop.c:2275
process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
-> #5 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
process_one_work+0x7bb/0x1010 kernel/workqueue.c:2286
worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
-> #4 ((null)){+.+.}-{0:0}:
flush_workqueue+0x16c/0x13d0 kernel/workqueue.c:2830
drain_workqueue+0xcf/0x380 kernel/workqueue.c:2995
destroy_workqueue+0x7b/0xb20 kernel/workqueue.c:4439
__loop_clr_fd+0x234/0xb90 drivers/block/loop.c:1384
blkdev_put_whole block/bdev.c:692 [inline]
blkdev_put+0x53f/0x7d0 block/bdev.c:957
blkdev_close+0x76/0xa0 block/fops.c:478
__fput+0x234/0x930 fs/file_table.c:311
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #3 (&lo->lo_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_killable_nested+0x17/0x20 kernel/locking/mutex.c:758
lo_open+0x6a/0x100 drivers/block/loop.c:2056
blkdev_get_whole+0x90/0x390 block/bdev.c:669
blkdev_get_by_dev+0x2d0/0xa60 block/bdev.c:827
blkdev_open+0x12d/0x2c0 block/fops.c:466
do_dentry_open+0x7ff/0xf80 fs/open.c:826
do_open fs/namei.c:3616 [inline]
path_openat+0x26f5/0x2fa0 fs/namei.c:3750
do_filp_open+0x1e2/0x410 fs/namei.c:3777
do_sys_openat2+0x150/0x4b0 fs/open.c:1255
do_sys_open fs/open.c:1271 [inline]
__do_sys_openat fs/open.c:1287 [inline]
__se_sys_openat fs/open.c:1282 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1282
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #2 (&disk->open_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
bd_register_pending_holders+0x33/0x310 block/holder.c:161
device_add_disk+0x5a7/0xd40 block/genhd.c:486
add_disk include/linux/genhd.h:200 [inline]
nbd_dev_add+0x757/0xb20 drivers/block/nbd.c:1786
nbd_genl_connect+0x850/0x18a0 drivers/block/nbd.c:1927
genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
genl_rcv_msg+0xcea/0xf90 net/netlink/genetlink.c:792
netlink_rcv_skb+0x1f5/0x440 net/netlink/af_netlink.c:2507
genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
__sys_sendmsg net/socket.c:2528 [inline]
__do_sys_sendmsg net/socket.c:2537 [inline]
__se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
-> #1 (genl_mutex){+.+.}-{3:3}:
__mutex_lock_common+0x1e3/0x2400 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
genl_lock net/netlink/genetlink.c:33 [inline]
genl_lock_all net/netlink/genetlink.c:46 [inline]
genl_register_family+0x3f0/0x10f0 net/netlink/genetlink.c:393
vdpa_init+0x35/0x70 drivers/vdpa/vdpa.c:903
do_one_initcall+0x272/0x730 init/main.c:1316
do_initcall_level+0x137/0x1f0 init/main.c:1389
do_initcalls+0x4b/0x90 init/main.c:1405
kernel_init_freeable+0x3e9/0x570 init/main.c:1629
kernel_init+0x19/0x1b0 init/main.c:1520
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
-> #0 (cb_lock){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
sock_sendmsg net/socket.c:741 [inline]
kernel_sendmsg+0x234/0x350 net/socket.c:765
sock_no_sendpage+0x12a/0x1a0 net/core/sock.c:3045
kernel_sendpage+0x2cb/0x380 net/socket.c:3548
sock_sendpage+0x7a/0xb0 net/socket.c:1027
pipe_to_sendpage+0x22f/0x320 fs/splice.c:364
splice_from_pipe_feed fs/splice.c:418 [inline]
__splice_from_pipe+0x302/0x820 fs/splice.c:562
splice_from_pipe fs/splice.c:597 [inline]
generic_splice_sendpage+0x111/0x180 fs/splice.c:746
do_splice_from fs/splice.c:767 [inline]
do_splice+0xe5a/0x1640 fs/splice.c:1108
__do_splice fs/splice.c:1173 [inline]
__do_sys_splice fs/splice.c:1379 [inline]
__se_sys_splice+0x34d/0x440 fs/splice.c:1361
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
other info that might help us debug this:
Chain exists of:
cb_lock --> sb_writers#3 --> &pipe->mutex/1
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&pipe->mutex/1);
lock(sb_writers#3);
lock(&pipe->mutex/1);
lock(cb_lock);
*** DEADLOCK ***
1 lock held by syz.6.5397/23098:
#0: ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:596 [inline]
#0: ffff88801ee97868 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:746
stack backtrace:
CPU: 1 PID: 23098 Comm: syz.6.5397 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain kernel/locking/lockdep.c:3788 [inline]
__lock_acquire+0x2c42/0x7d10 kernel/locking/lockdep.c:5012
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x774/0x920 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
sock_sendmsg net/socket.c:741 [inline]
kernel_sendmsg+0x234/0x350 net/socket.c:765
sock_no_sendpage+0x12a/0x1a0 net/core/sock.c:3045
kernel_sendpage+0x2cb/0x380 net/socket.c:3548
sock_sendpage+0x7a/0xb0 net/socket.c:1027
pipe_to_sendpage+0x22f/0x320 fs/splice.c:364
splice_from_pipe_feed fs/splice.c:418 [inline]
__splice_from_pipe+0x302/0x820 fs/splice.c:562
splice_from_pipe fs/splice.c:597 [inline]
generic_splice_sendpage+0x111/0x180 fs/splice.c:746
do_splice_from fs/splice.c:767 [inline]
do_splice+0xe5a/0x1640 fs/splice.c:1108
__do_splice fs/splice.c:1173 [inline]
__do_sys_splice fs/splice.c:1379 [inline]
__se_sys_splice+0x34d/0x440 fs/splice.c:1361
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f81af7ace59
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:00007f81ad9e5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f81afa26090 RCX: 00007f81af7ace59
RDX: 0000000000000007 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f81af842d6f R08: 000200000000622c R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f81afa26128 R14: 00007f81afa26090 R15: 00007ffd0d9e4588
</TASK>
---
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