[v5.15] INFO: task hung in exfat_write_inode

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syzbot

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Apr 13, 2024, 3:03:33 PMApr 13
to syzkaller...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: fa3df276cd36 Linux 5.15.155
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1081afeb180000
kernel config: https://syzkaller.appspot.com/x/.config?x=f12ea3f162537c9c
dashboard link: https://syzkaller.appspot.com/bug?extid=f008b2efefe15842ea1e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/feaf3fb3f68f/disk-fa3df276.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/537c519f1dd0/vmlinux-fa3df276.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5396ec75d1be/bzImage-fa3df276.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f008b2...@syzkaller.appspotmail.com

INFO: task kworker/u4:7:3824 blocked for more than 143 seconds.
Not tainted 5.15.155-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:7 state:D stack:20416 pid: 3824 ppid: 2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:4)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5030 [inline]
__schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
schedule+0x11b/0x1f0 kernel/sched/core.c:6459
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518
__mutex_lock_common+0xe34/0x25a0 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
exfat_write_inode+0x65/0x110 fs/exfat/inode.c:87
write_inode fs/fs-writeback.c:1495 [inline]
__writeback_single_inode+0x644/0xe30 fs/fs-writeback.c:1705
writeback_sb_inodes+0xbce/0x1a40 fs/fs-writeback.c:1930
__writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:2001
wb_writeback+0x465/0xc50 fs/fs-writeback.c:2106
wb_check_background_flush fs/fs-writeback.c:2172 [inline]
wb_do_writeback fs/fs-writeback.c:2260 [inline]
wb_workfn+0xd07/0x1130 fs/fs-writeback.c:2288
process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
kthread+0x3f6/0x4f0 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c91fae0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3264:
#0: ffff888024787098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002bab2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158
3 locks held by syz-executor.4/3517:
4 locks held by kworker/u4:7/3824:
#0: ffff888142f9e938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
#1: ffffc90004a47d20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
#2: ffff8880781700e0 (&type->s_umount_key#86){++++}-{3:3}, at: trylock_super+0x1b/0xf0 fs/super.c:418
#3: ffff8880192120e0 (&sbi->s_lock#2){+.+.}-{3:3}, at: exfat_write_inode+0x65/0x110 fs/exfat/inode.c:87
3 locks held by kworker/u4:11/5753:

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.155-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0xe72/0xeb0 kernel/hung_task.c:295
kthread+0x3f6/0x4f0 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3675 Comm: kworker/u4:6 Not tainted 5.15.155-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: phy3 ieee80211_iface_work
RIP: 0010:ieee80211_ibss_process_chanswitch+0x14b/0xf70 net/mac80211/ibss.c:786
Code: 00 48 89 5c 24 38 4c 63 33 bf 08 00 00 00 44 89 f6 e8 69 26 d4 f7 49 83 fe 08 73 28 b8 c3 00 00 00 31 db 44 0f a3 f0 0f 92 c3 <31> ff 89 de e8 4c 25 d4 f7 84 db 75 1a e8 e3 22 d4 f7 41 bd 00 08
RSP: 0018:ffffc900010ef720 EFLAGS: 00000247
RAX: 00000000000000c3 RBX: 0000000000000001 RCX: ffff88807e6b0000
RDX: ffff88807e6b0000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: ffffc900010ef9b0 R08: ffffffff89ac39d7 R09: ffffc900010ef910
R10: 0000000000000000 R11: dffffc0000000001 R12: dffffc0000000000
R13: ffff88805eb1f8c8 R14: 0000000000000000 R15: 1ffff1100bd3fb64
FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0dbe3ce000 CR3: 0000000061d98000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
ieee80211_rx_bss_info net/mac80211/ibss.c:1151 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1614 [inline]
ieee80211_ibss_rx_queued_mgmt+0x1b47/0x2af0 net/mac80211/ibss.c:1643
ieee80211_iface_process_skb net/mac80211/iface.c:1441 [inline]
ieee80211_iface_work+0x78f/0xcc0 net/mac80211/iface.c:1495
process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
kthread+0x3f6/0x4f0 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
</TASK>


---
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syzbot

unread,
May 12, 2024, 2:07:36 PMMay 12
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:

HEAD commit: 284087d4f7d5 Linux 5.15.158
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16853f70980000
kernel config: https://syzkaller.appspot.com/x/.config?x=b0dd54e4b5171ebc
dashboard link: https://syzkaller.appspot.com/bug?extid=f008b2efefe15842ea1e
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=120afcd0980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1320d884980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c2e33c1db6bf/disk-284087d4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d9f77284af1d/vmlinux-284087d4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a600323dd149/bzImage-284087d4.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/8fbb9e732058/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f008b2...@syzkaller.appspotmail.com

INFO: task kworker/u4:0:9 blocked for more than 143 seconds.
Not tainted 5.15.158-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:0 state:D stack:24000 pid: 9 ppid: 2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5030 [inline]
__schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
schedule+0x11b/0x1f0 kernel/sched/core.c:6459
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518
__mutex_lock_common+0xe34/0x25a0 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
exfat_write_inode+0x65/0x110 fs/exfat/inode.c:87
write_inode fs/fs-writeback.c:1495 [inline]
__writeback_single_inode+0x644/0xe30 fs/fs-writeback.c:1705
writeback_sb_inodes+0xbce/0x1a40 fs/fs-writeback.c:1930
__writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:2001
wb_writeback+0x465/0xc50 fs/fs-writeback.c:2106
wb_check_background_flush fs/fs-writeback.c:2172 [inline]
wb_do_writeback fs/fs-writeback.c:2260 [inline]
wb_workfn+0xd07/0x1130 fs/fs-writeback.c:2288
process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
kthread+0x3f6/0x4f0 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
</TASK>

Showing all locks held in the system:
4 locks held by kworker/u4:0/9:
#0: ffff8881425c6938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
#1: ffffc90000ce7d20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
#2: ffff8880781100e0 (&type->s_umount_key#43){.+.+}-{3:3}, at: trylock_super+0x1b/0xf0 fs/super.c:418
#3: ffff8880151de0e0 (&sbi->s_lock){+.+.}-{3:3}, at: exfat_write_inode+0x65/0x110 fs/exfat/inode.c:87
1 lock held by khungtaskd/27:
#0: ffffffff8c91fae0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3258:
#0: ffff88814adc9098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc900024b32e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158
3 locks held by syz-executor299/3540:

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.15.158-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0xe72/0xeb0 kernel/hung_task.c:295
kthread+0x3f6/0x4f0 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3540 Comm: syz-executor299 Not tainted 5.15.158-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:kasan_check_range+0x5/0x290 mm/kasan/generic.c:188
Code: c7 e8 6f 3b 54 08 31 c0 c3 0f 0b b8 ea ff ff ff c3 0f 0b b8 ea ff ff ff c3 cc cc cc cc cc cc cc cc cc cc cc cc 55 41 57 41 56 <53> b0 01 48 85 f6 0f 84 9a 01 00 00 48 89 fd 48 01 f5 0f 82 59 02
RSP: 0018:ffffc90002db7408 EFLAGS: 00000246
RAX: ffffffff81ac52b2 RBX: 0000000000000000 RCX: ffffffff81ac52c2
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffea000158be40
RBP: ffffea000158be40 R08: ffffffff81ac529a R09: fffff940002b17c9
R10: 0000000000000000 R11: dffffc0000000001 R12: 00fff00000002032
R13: dffffc0000000000 R14: ffffea000158be48 R15: ffffea000158be40
FS: 0000555555a27380(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560ebb45d600 CR3: 00000000764af000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
instrument_atomic_read include/linux/instrumented.h:71 [inline]
test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
PageUnevictable include/linux/page-flags.h:424 [inline]
mark_page_accessed+0x282/0x1330 mm/swap.c:408
__find_get_block+0x2d7/0x1350 fs/buffer.c:1314
__getblk_gfp+0x2d/0xaf0 fs/buffer.c:1332
__bread_gfp+0x2a/0x390 fs/buffer.c:1381
sb_bread include/linux/buffer_head.h:337 [inline]
exfat_get_dentry+0x678/0x970 fs/exfat/dir.c:741
exfat_readdir fs/exfat/dir.c:122 [inline]
exfat_iterate+0xc09/0x34a0 fs/exfat/dir.c:258
iterate_dir+0x224/0x570
__do_sys_getdents64 fs/readdir.c:369 [inline]
__se_sys_getdents64+0x209/0x4f0 fs/readdir.c:354
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f10a0d1b0a3
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 82 48 fb ff 66 90 b8 ff ff ff 7f 48 39 c2 48 0f 47 d0 b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 c7 c2 b8 ff ff ff f7 d8
RSP: 002b:00007ffc22ca03a8 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0000555555a30730 RCX: 00007f10a0d1b0a3
RDX: 0000000000008000 RSI: 0000555555a30730 RDI: 0000000000000004
RBP: 0000555555a30704 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000293 R12: ffffffffffffffb8
R13: 0000000000000010 R14: 0000555555a30700 R15: 00007ffc22ca2620
</TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.111 msecs


---
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