syzbot
possible deadlock in mnt_want_write
Status:
upstream: reported on 2026/08/01 11:19
Reported-by: syzbot+23cd16f26e4e42571f8d@syzkaller.appspotmail.com
First crash: 5d06h, last: 18h55m
Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.4946/24451 is trying to acquire lock:
ffff88807d5b6418 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:412
but task is already holding lock:
ffff88801dbf8870 (&subsys->lock){+.+.}-{3:3}, at: nvmet_ns_enable+0x4d/0x8c0 drivers/nvme/target/core.c:561
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&subsys->lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
nvmet_ns_device_path_store+0x54/0x150 drivers/nvme/target/configfs.c:350
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x312/0x400 fs/configfs/file.c:229
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x474/0x9a0 fs/read_write.c:584
ksys_write+0x151/0x260 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #5 (&p->frag_sem){.+.+}-{3:3}:
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
fill_read_buffer fs/configfs/file.c:66 [inline]
configfs_read_iter+0x1a5/0x570 fs/configfs/file.c:88
__kernel_read+0x2e5/0x730 fs/read_write.c:428
integrity_kernel_read+0x8a/0xd0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xb1f/0x1960 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x4d4/0xa30 security/integrity/ima/ima_api.c:290
process_measurement+0x123a/0x1d50 security/integrity/ima/ima_main.c:370
ima_file_check+0xcc/0x110 security/integrity/ima/ima_main.c:568
do_open fs/namei.c:3685 [inline]
path_openat+0x2910/0x3270 fs/namei.c:3844
do_filp_open+0x1f2/0x430 fs/namei.c:3871
do_sys_openat2+0x134/0x1d0 fs/open.c:1422
do_sys_open fs/open.c:1437 [inline]
__do_sys_openat fs/open.c:1453 [inline]
__se_sys_openat fs/open.c:1448 [inline]
__x64_sys_openat+0x139/0x160 fs/open.c:1448
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #4 (&buffer->mutex){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
configfs_read_iter+0x72/0x570 fs/configfs/file.c:86
__kernel_read+0x2e5/0x730 fs/read_write.c:428
integrity_kernel_read+0x8a/0xd0 security/integrity/iint.c:221
ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
ima_calc_file_hash+0xb1f/0x1960 security/integrity/ima/ima_crypto.c:573
ima_collect_measurement+0x4d4/0xa30 security/integrity/ima/ima_api.c:290
process_measurement+0x123a/0x1d50 security/integrity/ima/ima_main.c:370
ima_file_check+0xcc/0x110 security/integrity/ima/ima_main.c:568
do_open fs/namei.c:3685 [inline]
path_openat+0x2910/0x3270 fs/namei.c:3844
do_filp_open+0x1f2/0x430 fs/namei.c:3871
do_sys_openat2+0x134/0x1d0 fs/open.c:1422
do_sys_open fs/open.c:1437 [inline]
__do_sys_openat fs/open.c:1453 [inline]
__se_sys_openat fs/open.c:1448 [inline]
__x64_sys_openat+0x139/0x160 fs/open.c:1448
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #3 (&iint_mutex_key[depth]){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
process_measurement+0x739/0x1d50 security/integrity/ima/ima_main.c:275
ima_file_check+0xcc/0x110 security/integrity/ima/ima_main.c:568
do_open fs/namei.c:3685 [inline]
path_openat+0x2910/0x3270 fs/namei.c:3844
do_file_open_root+0x2f3/0x5a0 fs/namei.c:3896
file_open_root+0x167/0x1c0 fs/open.c:1402
kernel_read_file_from_path_initns+0x151/0x230 fs/kernel_read_file.c:163
fw_get_filesystem_firmware drivers/base/firmware_loader/main.c:548 [inline]
_request_firmware+0xb43/0x1520 drivers/base/firmware_loader/main.c:911
request_firmware+0x36/0x50 drivers/base/firmware_loader/main.c:987
reg_reload_regdb+0x9a/0x490 net/wireless/reg.c:1078
genl_family_rcv_msg_doit+0x21a/0x310 net/netlink/genetlink.c:971
genl_family_rcv_msg net/netlink/genetlink.c:1051 [inline]
genl_rcv_msg+0x611/0x7a0 net/netlink/genetlink.c:1066
netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1075
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x61b/0x980 net/socket.c:2595
___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2687 [inline]
__se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #2 (cb_lock){++++}-{3:3}:
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074
netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_sendmsg+0x23b/0x3a0 net/socket.c:768
splice_to_socket+0xb92/0x1270 fs/splice.c:881
do_splice_from fs/splice.c:933 [inline]
do_splice+0xe45/0x1b20 fs/splice.c:1292
__do_splice fs/splice.c:1370 [inline]
__do_sys_splice fs/splice.c:1586 [inline]
__se_sys_splice+0x398/0x4a0 fs/splice.c:1568
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #1 (&pipe->mutex/1){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
iter_file_splice_write+0x1ba/0xcf0 fs/splice.c:683
do_splice_from fs/splice.c:933 [inline]
do_splice+0xe45/0x1b20 fs/splice.c:1292
__do_splice fs/splice.c:1370 [inline]
__do_sys_splice fs/splice.c:1586 [inline]
__se_sys_splice+0x398/0x4a0 fs/splice.c:1568
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #0 (sb_writers#5){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1633 [inline]
sb_start_write+0x4d/0x1c0 include/linux/fs.h:1708
mnt_want_write+0x41/0x90 fs/namespace.c:412
open_last_lookups fs/namei.c:3596 [inline]
path_openat+0x768/0x3270 fs/namei.c:3841
do_filp_open+0x1f2/0x430 fs/namei.c:3871
file_open_name fs/open.c:1367 [inline]
filp_open+0x180/0x1e0 fs/open.c:1387
nvmet_file_ns_enable+0x74/0x330 drivers/nvme/target/io-cmd-file.c:41
nvmet_ns_enable+0xf4/0x8c0 drivers/nvme/target/core.c:578
nvmet_ns_enable_store+0xd8/0x170 drivers/nvme/target/configfs.c:549
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x312/0x400 fs/configfs/file.c:229
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x474/0x9a0 fs/read_write.c:584
ksys_write+0x151/0x260 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
other info that might help us debug this:
Chain exists of:
sb_writers#5 --> &p->frag_sem --> &subsys->lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&subsys->lock);
lock(&p->frag_sem);
lock(&subsys->lock);
rlock(sb_writers#5);
*** DEADLOCK ***
6 locks held by syz.5.4946/24451:
#0: ffff88807d78ed48 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040
#1: ffff8880187b2418 (sb_writers#20){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580
#2: ffff888067ff3288 (&buffer->mutex){+.+.}-{3:3}, at: configfs_write_iter+0x81/0x400 fs/configfs/file.c:226
#3: ffff88802fa54878 (&p->frag_sem){.+.+}-{3:3}, at: flush_write_buffer fs/configfs/file.c:205 [inline]
#3: ffff88802fa54878 (&p->frag_sem){.+.+}-{3:3}, at: configfs_write_iter+0x215/0x400 fs/configfs/file.c:229
#4: ffffffff8daef0f0 (nvmet_config_sem){+.+.}-{3:3}, at: nvmet_ns_enable_store+0xc9/0x170 drivers/nvme/target/configfs.c:547
#5: ffff88801dbf8870 (&subsys->lock){+.+.}-{3:3}, at: nvmet_ns_enable+0x4d/0x8c0 drivers/nvme/target/core.c:561
stack backtrace:
CPU: 0 PID: 24451 Comm: syz.5.4946 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1633 [inline]
sb_start_write+0x4d/0x1c0 include/linux/fs.h:1708
mnt_want_write+0x41/0x90 fs/namespace.c:412
open_last_lookups fs/namei.c:3596 [inline]
path_openat+0x768/0x3270 fs/namei.c:3841
do_filp_open+0x1f2/0x430 fs/namei.c:3871
file_open_name fs/open.c:1367 [inline]
filp_open+0x180/0x1e0 fs/open.c:1387
nvmet_file_ns_enable+0x74/0x330 drivers/nvme/target/io-cmd-file.c:41
nvmet_ns_enable+0xf4/0x8c0 drivers/nvme/target/core.c:578
nvmet_ns_enable_store+0xd8/0x170 drivers/nvme/target/configfs.c:549
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x312/0x400 fs/configfs/file.c:229
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x474/0x9a0 fs/read_write.c:584
ksys_write+0x151/0x260 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3ffc19e0d9
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:00007f3ffd05a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f3ffc425fa0 RCX: 00007f3ffc19e0d9
RDX: 0000000000000001 RSI: 0000200000000300 RDI: 0000000000000007
RBP: 00007f3ffc235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3ffc426038 R14: 00007f3ffc425fa0 R15: 00007ffc5c31f3c8
</TASK>
nvmet: failed to open file ./fi: (-2)
Struck through repros no longer work on HEAD.