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Message-ID: <67c96915.050a0220.15b4b9.0031.GAE@google.com>
Date: Thu, 06 Mar 2025 01:21:25 -0800
From: syzbot <syzbot+6983c03a6a28616e362f@...kaller.appspotmail.com>
To: brauner@...nel.org, jack@...e.cz, kent.overstreet@...ux.dev,
linkinjeon@...nel.org, linux-bcachefs@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
sj1557.seo@...sung.com, syzkaller-bugs@...glegroups.com,
viro@...iv.linux.org.uk, yuezhang.mo@...y.com
Subject: Re: [syzbot] [bcachefs?] INFO: task hung in vfs_unlink (5)
syzbot has found a reproducer for the following issue on:
HEAD commit: bb2281fb05e5 Merge tag 'x86_microcode_for_v6.14_rc6' of gi..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=159144b7980000
kernel config: https://syzkaller.appspot.com/x/.config?x=523d3ff8e053340a
dashboard link: https://syzkaller.appspot.com/bug?extid=6983c03a6a28616e362f
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12cf7078580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10197da8580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7f163a5da7e8/disk-bb2281fb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6841e1105518/vmlinux-bb2281fb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3295ae6e86c0/bzImage-bb2281fb.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/8d22fecc87c0/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=17e97da8580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6983c03a6a28616e362f@...kaller.appspotmail.com
INFO: task syz-executor399:5826 blocked for more than 143 seconds.
Not tainted 6.14.0-rc5-syzkaller-00023-gbb2281fb05e5 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor399 state:D stack:27224 pid:5826 tgid:5823 ppid:5821 task_flags:0x400040 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5378 [inline]
__schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
__schedule_loop kernel/sched/core.c:6842 [inline]
schedule+0x14b/0x320 kernel/sched/core.c:6857
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914
rwsem_down_write_slowpath+0xeee/0x13b0 kernel/locking/rwsem.c:1176
__down_write_common kernel/locking/rwsem.c:1304 [inline]
__down_write kernel/locking/rwsem.c:1313 [inline]
down_write+0x1d7/0x220 kernel/locking/rwsem.c:1578
inode_lock include/linux/fs.h:877 [inline]
vfs_unlink+0xe4/0x650 fs/namei.c:4514
do_unlinkat+0x4ae/0x830 fs/namei.c:4589
__do_sys_unlink fs/namei.c:4637 [inline]
__se_sys_unlink fs/namei.c:4635 [inline]
__x64_sys_unlink+0x47/0x50 fs/namei.c:4635
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb1339de6f9
RSP: 002b:00007fb133974218 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007fb133a665f8 RCX: 00007fb1339de6f9
RDX: 00007fb1339b7dc6 RSI: 0000000000000000 RDI: 0000400000000100
RBP: 00007fb133a665f0 R08: 00007ffcb7766927 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0031656c69662f2e
R13: 0000400000000100 R14: 0000400000000080 R15: 0000400000000240
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/30:
#0: ffffffff8eb392e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#0: ffffffff8eb392e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8eb392e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6746
2 locks held by getty/5580:
#0: ffff88814e4bb0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900033332f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x616/0x1770 drivers/tty/n_tty.c:2211
2 locks held by syz-executor399/5825:
3 locks held by syz-executor399/5826:
#0: ffff888076078420 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:547
#1: ffff888073c182a0 (&sb->s_type->i_mutex_key#14/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:912 [inline]
#1: ffff888073c182a0 (&sb->s_type->i_mutex_key#14/1){+.+.}-{4:4}, at: do_unlinkat+0x26a/0x830 fs/namei.c:4576
#2: ffff888073c18910 (&sb->s_type->i_mutex_key#14){++++}-{4:4}, at: inode_lock include/linux/fs.h:877 [inline]
#2: ffff888073c18910 (&sb->s_type->i_mutex_key#14){++++}-{4:4}, at: vfs_unlink+0xe4/0x650 fs/namei.c:4514
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.14.0-rc5-syzkaller-00023-gbb2281fb05e5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
watchdog+0x1058/0x10a0 kernel/hung_task.c:399
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5825 Comm: syz-executor399 Not tainted 6.14.0-rc5-syzkaller-00023-gbb2281fb05e5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:210
Code: 89 fb e8 23 00 00 00 48 8b 3d a4 04 92 0c 48 89 de 5b e9 23 5e 59 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0c 25 00 d5 03 00 65 8b 15 30 06
RSP: 0018:ffffc900040c78e8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888023a2ce00 RCX: ffffffff824af6cf
RDX: ffff8880330e5a00 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff824af6f1 R09: 1ffff1100f76b200
R10: dffffc0000000000 R11: ffffed100f76b201 R12: 0000000000000008
R13: ffff888023a2c500 R14: 0000000000000200 R15: ffff88807bb59000
FS: 00007fb1339956c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005592141bc600 CR3: 0000000035948000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
__bread_gfp+0xca/0x400 fs/buffer.c:1487
sb_bread include/linux/buffer_head.h:346 [inline]
__exfat_ent_get fs/exfat/fatent.c:48 [inline]
exfat_ent_get+0x14d/0x400 fs/exfat/fatent.c:97
exfat_find_last_cluster+0x15d/0x380 fs/exfat/fatent.c:263
exfat_cont_expand fs/exfat/file.c:40 [inline]
exfat_setattr+0xa8d/0x1a90 fs/exfat/file.c:295
notify_change+0xbca/0xe90 fs/attr.c:552
do_truncate+0x220/0x310 fs/open.c:65
vfs_truncate+0x492/0x530 fs/open.c:115
do_sys_truncate+0xdb/0x190 fs/open.c:138
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb1339de6f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 18 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb133995218 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007fb133a665e8 RCX: 00007fb1339de6f9
RDX: ffffffffffffffb0 RSI: 000000000000f000 RDI: 0000400000000080
RBP: 00007fb133a665e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0031656c69662f2e
R13: 0000400000000100 R14: 0000400000000080 R15: 0000400000000240
</TASK>
---
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.
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