Re: [syzbot] [block?] [trace?] INFO: task hung in blk_trace_startstop

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    635c467cc14e Add linux-next specific files for 20260213
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14d8ec02580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f09eec269f9f4746
dashboard link: https://syzkaller.appspot.com/bug?extid=774863666ef5b025c9d0
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12cc2ffa580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/24870d51cbd0/disk-635c467c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/49283c738806/vmlinux-635c467c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8c5f9d1da977/bzImage-635c467c.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b01c09978893/mount_0.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=163e915a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+774863666ef5b025c9d0@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: task syz.3.20:6102 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.20        state:D stack:28368 pid:6102  tgid:6087  ppid:5957   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1585/0x5340 kernel/sched/core.c:6907
 __schedule_loop kernel/sched/core.c:6989 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7004
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7061
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 blk_trace_startstop+0x8f/0x610 kernel/trace/blktrace.c:901
 blk_trace_ioctl+0x315/0x740 kernel/trace/blktrace.c:947
 blkdev_common_ioctl+0x13a7/0x3250 block/ioctl.c:724
 blkdev_ioctl+0x528/0x740 block/ioctl.c:798
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f530c39bf79
RSP: 002b:00007f530d2e4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f530c616180 RCX: 00007f530c39bf79
RDX: 0000000000000000 RSI: 0000000000001275 RDI: 0000000000000007
RBP: 00007f530c4327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f530c616218 R14: 00007f530c616180 R15: 00007ffdd027c568
 </TASK>
INFO: task syz.2.19:6109 blocked for more than 150 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.19        state:D stack:26720 pid:6109  tgid:6091  ppid:5955   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1585/0x5340 kernel/sched/core.c:6907
 __schedule_loop kernel/sched/core.c:6989 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7004
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7061
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0x7fe/0x1300 kernel/locking/mutex.c:776
 relay_open+0x3b8/0x920 kernel/relay.c:516
 blk_trace_setup_prepare+0x425/0x5a0 kernel/trace/blktrace.c:716
 blk_trace_setup+0x2c0/0x430 kernel/trace/blktrace.c:789
 blk_trace_ioctl+0x380/0x740 kernel/trace/blktrace.c:935


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.