[syzbot] [f2fs?] INFO: task hung in f2fs_balance_fs

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0988a0ea7919 Merge tag 'for-v6.3-part2' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1666fbb0c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=cab35c936731a347
dashboard link: https://syzkaller.appspot.com/bug?extid=8b85865808c8908a0d8c
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c3d3396c296c/disk-0988a0ea.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/16cef168e621/vmlinux-0988a0ea.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4324b131ded6/bzImage-0988a0ea.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8b8586...@syzkaller.appspotmail.com

INFO: task kworker/u4:11:5360 blocked for more than 143 seconds.
Not tainted 6.2.0-syzkaller-13467-g0988a0ea7919 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:11 state:D stack:25896 pid:5360 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:5)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5304 [inline]
__schedule+0xcce/0x5b20 kernel/sched/core.c:6622
schedule+0xde/0x1a0 kernel/sched/core.c:6698
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6757
rwsem_down_write_slowpath+0x3e2/0x1220 kernel/locking/rwsem.c:1178
__down_write_common kernel/locking/rwsem.c:1306 [inline]
__down_write kernel/locking/rwsem.c:1315 [inline]
down_write+0x1d2/0x200 kernel/locking/rwsem.c:1574
f2fs_down_write fs/f2fs/f2fs.h:2207 [inline]
f2fs_balance_fs+0x54e/0x6c0 fs/f2fs/segment.c:427
f2fs_write_inode+0x582/0xe00 fs/f2fs/inode.c:760
write_inode fs/fs-writeback.c:1453 [inline]
__writeback_single_inode+0xd38/0x14d0 fs/fs-writeback.c:1665
writeback_sb_inodes+0x54d/0xfa0 fs/fs-writeback.c:1891
__writeback_inodes_wb+0xc6/0x280 fs/fs-writeback.c:1962
wb_writeback+0x8d6/0xdd0 fs/fs-writeback.c:2067
wb_check_old_data_flush fs/fs-writeback.c:2167 [inline]
wb_do_writeback fs/fs-writeback.c:2220 [inline]
wb_workfn+0x88a/0x1340 fs/fs-writeback.c:2248
process_one_work+0x9bf/0x1820 kernel/workqueue.c:2390
worker_thread+0x669/0x1090 kernel/workqueue.c:2537
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8c794e30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:510
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8c794b30 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:510
1 lock held by khungtaskd/28:
#0: ffffffff8c795980 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x340 kernel/locking/lockdep.c:6495
2 locks held by getty/4752:
#0: ffff88814a459098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x26/0x80 drivers/tty/tty_ldisc.c:244
#1: ffffc900015a02f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef4/0x13e0 drivers/tty/n_tty.c:2177
4 locks held by kworker/u4:11/5360:
#0: ffff888144ade138 ((wq_completion)writeback){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff888144ade138 ((wq_completion)writeback){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
#0: ffff888144ade138 ((wq_completion)writeback){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
#0: ffff888144ade138 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:639 [inline]
#0: ffff888144ade138 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:666 [inline]
#0: ffff888144ade138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x86d/0x1820 kernel/workqueue.c:2361
#1: ffffc900053dfda8 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x8a1/0x1820 kernel/workqueue.c:2365
#2: ffff8880205a80e0 (&type->s_umount_key#76){++++}-{3:3}, at: trylock_super+0x21/0x110 fs/super.c:414
#3: ffff8880813012a8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2207 [inline]
#3: ffff8880813012a8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x54e/0x6c0 fs/f2fs/segment.c:427
2 locks held by syz-executor.5/13735:
1 lock held by syz-executor.4/13932:

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.2.0-syzkaller-13467-g0988a0ea7919 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
nmi_cpu_backtrace+0x316/0x3e0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x33f/0x460 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
watchdog+0xe94/0x11e0 kernel/hung_task.c:379
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 13735 Comm: syz-executor.5 Not tainted 6.2.0-syzkaller-13467-g0988a0ea7919 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
RIP: 0010:__might_sleep+0x21/0x160 kernel/sched/core.c:9975
Code: 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 48 b8 00 00 00 00 00 fc ff df 41 54 41 89 f4 55 48 89 fd 53 65 48 8b 1c 25 80 b8 03 00 <48> 8d 7b 18 48 83 ec 10 48 89 fa 48 c1 ea 03 0f b6 04 02 84 c0 74
RSP: 0018:ffffc9001571e308 EFLAGS: 00000286
RAX: dffffc0000000000 RBX: ffff88803edcba80 RCX: 0000000000000000
RDX: ffff88803edcba80 RSI: 00000000000005ef RDI: ffffffff8a4c5ec0
RBP: ffffffff8a4c5ec0 R08: 0000000000000004 R09: 0000000000000200
R10: 0000000000000001 R11: 0000000000094001 R12: 00000000000005ef
R13: 0000000000000001 R14: dffffc0000000000 R15: 000000000000000b
FS: 00007f3f5dda8700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555556b08888 CR3: 0000000079d24000 CR4: 0000000000350ee0
Call Trace:
<TASK>
down_read+0x19/0x50 kernel/locking/rwsem.c:1519
check_valid_map fs/f2fs/gc.c:958 [inline]
gc_data_segment fs/f2fs/gc.c:1510 [inline]
do_garbage_collect+0x1b42/0x3e30 fs/f2fs/gc.c:1739
f2fs_gc+0x890/0x20e0 fs/f2fs/gc.c:1837
f2fs_balance_fs+0x55b/0x6c0 fs/f2fs/segment.c:428
f2fs_write_single_data_page+0x13f5/0x1930 fs/f2fs/data.c:2897
f2fs_write_cache_pages+0xce9/0x1ef0 fs/f2fs/data.c:3144
__f2fs_write_data_pages fs/f2fs/data.c:3295 [inline]
f2fs_write_data_pages+0x4c7/0x1270 fs/f2fs/data.c:3322
do_writepages+0x1a8/0x640 mm/page-writeback.c:2551
filemap_fdatawrite_wbc mm/filemap.c:390 [inline]
filemap_fdatawrite_wbc+0x147/0x1b0 mm/filemap.c:380
__filemap_fdatawrite_range+0xb8/0xf0 mm/filemap.c:423
file_write_and_wait_range+0xce/0x140 mm/filemap.c:781
f2fs_do_sync_file+0x3a4/0x2a60 fs/f2fs/file.c:273
f2fs_sync_file+0x13a/0x190 fs/f2fs/file.c:391
vfs_fsync_range+0x13e/0x230 fs/sync.c:188
generic_write_sync include/linux/fs.h:2452 [inline]
f2fs_file_write_iter+0x15d6/0x29a0 fs/f2fs/file.c:4727
__kernel_write_iter+0x262/0x7a0 fs/read_write.c:517
dump_emit_page fs/coredump.c:885 [inline]
dump_user_range+0x234/0x700 fs/coredump.c:912
elf_core_dump+0x277e/0x36e0 fs/binfmt_elf.c:2142
do_coredump+0x2d28/0x3cc0 fs/coredump.c:762
get_signal+0x1bff/0x25b0 kernel/signal.c:2845
arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203
irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:309
asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:564
RIP: 0033:0x7f3f5d08c101
Code: c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:00000000200002f0 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f3f5d1abf80 RCX: 00007f3f5d08c0f9
RDX: 0000000020000000 RSI: 00000000200002f0 RDI: 0000000000000000
RBP: 00007f3f5d0e7ae9 R08: 0000000020000300 R09: 0000000020000300
R10: 0000000020000180 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff58642dbf R14: 00007f3f5dda8300 R15: 0000000000022000
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 4bdec23f971b Merge tag 'hwmon-for-v6.3-rc4' of git://git.k..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=177bdf41c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ea09b0836073ee4

dashboard link: https://syzkaller.appspot.com/bug?extid=8b85865808c8908a0d8c
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1320ef41c80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=100b561ec80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d61c34161317/disk-4bdec23f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6f84b5727488/vmlinux-4bdec23f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1279076a5b70/bzImage-4bdec23f.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c38a9411ccc2/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8b8586...@syzkaller.appspotmail.com

INFO: task kworker/u4:4:56 blocked for more than 143 seconds.
Not tainted 6.3.0-rc3-syzkaller-00322-g4bdec23f971b #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:kworker/u4:4 state:D stack:26464 pid:56 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:0)

Call Trace:
<TASK>
context_switch kernel/sched/core.c:5304 [inline]

__schedule+0xc91/0x5770 kernel/sched/core.c:6622

schedule+0xde/0x1a0 kernel/sched/core.c:6698
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6757
rwsem_down_write_slowpath+0x3e2/0x1220 kernel/locking/rwsem.c:1178
__down_write_common kernel/locking/rwsem.c:1306 [inline]
__down_write kernel/locking/rwsem.c:1315 [inline]
down_write+0x1d2/0x200 kernel/locking/rwsem.c:1574
f2fs_down_write fs/f2fs/f2fs.h:2207 [inline]
f2fs_balance_fs+0x54e/0x6c0 fs/f2fs/segment.c:427
f2fs_write_inode+0x582/0xe00 fs/f2fs/inode.c:760
write_inode fs/fs-writeback.c:1453 [inline]

__writeback_single_inode+0x9f8/0xdc0 fs/fs-writeback.c:1665
writeback_sb_inodes+0x54d/0xe70 fs/fs-writeback.c:1891
__writeback_inodes_wb+0xc6/0x280 fs/fs-writeback.c:1962
wb_writeback+0x7e9/0xa50 fs/fs-writeback.c:2067

wb_check_old_data_flush fs/fs-writeback.c:2167 [inline]
wb_do_writeback fs/fs-writeback.c:2220 [inline]

wb_workfn+0x765/0xfc0 fs/fs-writeback.c:2248
process_one_work+0x991/0x15c0 kernel/workqueue.c:2390

worker_thread+0x669/0x1090 kernel/workqueue.c:2537
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:

#0: ffffffff8c794b70 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:510

1 lock held by rcu_tasks_trace/13:

#0: ffffffff8c794870 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:510

1 lock held by khungtaskd/28:

#0: ffffffff8c7956c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x340 kernel/locking/lockdep.c:6495
4 locks held by kworker/u4:4/56:
#0: ffff88801750f138 ((wq_completion)writeback){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff88801750f138 ((wq_completion)writeback){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
#0: ffff88801750f138 ((wq_completion)writeback){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
#0: ffff88801750f138 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:639 [inline]
#0: ffff88801750f138 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:666 [inline]
#0: ffff88801750f138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x87a/0x15c0 kernel/workqueue.c:2361
#1: ffffc90001577da8 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x15c0 kernel/workqueue.c:2365
#2: ffff8880244ae0e0 (&type->s_umount_key#44){.+.+}-{3:3}, at: trylock_super+0x21/0x110 fs/super.c:414
#3: ffff8880200f12a8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2207 [inline]
#3: ffff8880200f12a8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x54e/0x6c0 fs/f2fs/segment.c:427
2 locks held by getty/4755:
#0: ffff88802be78098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x26/0x80 drivers/tty/tty_ldisc.c:244

#1: ffffc900015a02f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef4/0x13e0 drivers/tty/n_tty.c:2177

3 locks held by syz-executor470/5084:
1 lock held by syz-executor470/5814:

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.3.0-rc3-syzkaller-00322-g4bdec23f971b #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106

nmi_cpu_backtrace+0x29c/0x350 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x2a4/0x300 lib/nmi_backtrace.c:62

trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]

watchdog+0xe16/0x1090 kernel/hung_task.c:379

kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>

Sending NMI from CPU 1 to CPUs 0:

NMI backtrace for cpu 0

CPU: 0 PID: 5814 Comm: syz-executor470 Not tainted 6.3.0-rc3-syzkaller-00322-g4bdec23f971b #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023

RIP: 0010:__sanitizer_cov_trace_pc+0x3b/0x70 kernel/kcov.c:207
Code: 81 e1 00 01 00 00 65 48 8b 14 25 80 b8 03 00 a9 00 01 ff 00 74 0e 85 c9 74 35 8b 82 74 15 00 00 85 c0 74 2b 8b 82 50 15 00 00 <83> f8 02 75 20 48 8b 8a 58 15 00 00 8b 92 54 15 00 00 48 8b 01 48
RSP: 0018:ffffc9000444f8b8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff88802bb0af58 RCX: 0000000000000000
RDX: ffff888026079d40 RSI: ffffffff81b30401 RDI: 0000000000000001
RBP: ffffea0001b5f3c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffc9000444fa48 R15: 0000000000000001
FS: 00007ff4d3fdc700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007ff4cfbbb000 CR3: 00000000294d8000 CR4: 0000000000350ef0
Call Trace:
<TASK>
truncate_inode_folio+0x51/0x70 mm/truncate.c:197
shmem_undo_range+0x33e/0x1340 mm/shmem.c:942
shmem_truncate_range mm/shmem.c:1041 [inline]
shmem_evict_inode+0x32f/0xb60 mm/shmem.c:1156
evict+0x2ed/0x6b0 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput.part.0+0x50a/0x740 fs/inode.c:1774
iput+0x5c/0x80 fs/inode.c:1764
dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:401
__dentry_kill+0x3c0/0x640 fs/dcache.c:607
dentry_kill fs/dcache.c:733 [inline]
dput+0x865/0xe10 fs/dcache.c:913
__fput+0x3cc/0xa90 fs/file_table.c:329
task_work_run+0x16f/0x270 kernel/task_work.c:179
ptrace_notify+0x118/0x140 kernel/signal.c:2354
ptrace_report_syscall include/linux/ptrace.h:411 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:473 [inline]
syscall_exit_work kernel/entry/common.c:251 [inline]
syscall_exit_to_user_mode_prepare+0x129/0x220 kernel/entry/common.c:278
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0xd/0x50 kernel/entry/common.c:296
do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7ff4d3feca4b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 03 fd ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 41 fd ff ff 8b 44
RSP: 002b:00007ff4d3fdc160 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007ff4d3feca4b
RDX: 0000000000000010 RSI: 0000000000004c00 RDI: 0000000000000003
RBP: 0000000000000004 R08: 0000000000000000 R09: 00000000000105f8
R10: 0000000000000000 R11: 0000000000000293 R12: 00007ff4d3fdc6b8
R13: 00007ff4d3fdc190 R14: 00007ff4d3fdc1d0 R15: 0000000000000010
</TASK>

[Hillf Danton]

On 25 Mar 2023 22:17:44 -0700

> HEAD commit: 4bdec23f971b Merge tag 'hwmon-for-v6.3-rc4' of git://git.k..
> git tree: upstream

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=100b561ec80000

See if sit_i->sentry_lock is acquired with page locked.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4bdec23f971b

--- x/fs/f2fs/gc.c
+++ y/fs/f2fs/gc.c
@@ -955,7 +955,8 @@ static int check_valid_map(struct f2fs_s
struct seg_entry *sentry;
int ret;

- down_read(&sit_i->sentry_lock);
+ if (!down_read_trylock(&sit_i->sentry_lock))
+ return 0;
sentry = get_seg_entry(sbi, segno);
ret = f2fs_test_bit(offset, sentry->cur_valid_map);
up_read(&sit_i->sentry_lock);
--

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in f2fs_balance_fs

INFO: task kworker/u4:6:3759 blocked for more than 143 seconds.
Not tainted 6.3.0-rc3-syzkaller-00322-g4bdec23f971b-dirty #0

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:kworker/u4:6 state:D stack:22904 pid:3759 ppid:2 flags:0x00004000

3 locks held by kworker/u4:1/11:
#0: ffff8880b983c298 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2f/0x120 kernel/sched/core.c:539
#1: ffffc90000107da8 ((work_completion)(&(&kfence_timer)->work)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x15c0 kernel/workqueue.c:2365
#2: ffffffff8c6409f0 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_disable+0x12/0x20 kernel/jump_label.c:242

1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8c794b70 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:510
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8c794870 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:510

1 lock held by khungtaskd/27:

#0: ffffffff8c7956c0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x340 kernel/locking/lockdep.c:6495

4 locks held by kworker/u4:6/3759:
#0: ffff88801731c938 ((wq_completion)writeback){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff88801731c938 ((wq_completion)writeback){+.+.}-{0:0}, at: arch_atomic_long_set include/linux/atomic/atomic-long.h:41 [inline]
#0: ffff88801731c938 ((wq_completion)writeback){+.+.}-{0:0}, at: atomic_long_set include/linux/atomic/atomic-instrumented.h:1280 [inline]
#0: ffff88801731c938 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:639 [inline]
#0: ffff88801731c938 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:666 [inline]
#0: ffff88801731c938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x87a/0x15c0 kernel/workqueue.c:2361
#1: ffffc9000f017da8 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x15c0 kernel/workqueue.c:2365
#2: ffff8880758ec0e0 (&type->s_umount_key#50){.+.+}-{3:3}, at: trylock_super+0x21/0x110 fs/super.c:414
#3: ffff88801ddb52a8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2207 [inline]
#3: ffff88801ddb52a8 (&sbi->gc_lock){+.+.}-{3:3}, at: f2fs_balance_fs+0x54e/0x6c0 fs/f2fs/segment.c:427
1 lock held by syslogd/4423:

2 locks held by getty/4752:

#0: ffff88802be94098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x26/0x80 drivers/tty/tty_ldisc.c:244

#1: ffffc900015a02f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef4/0x13e0 drivers/tty/n_tty.c:2177

2 locks held by syz-executor.0/5646:
3 locks held by syz-executor.0/6726:

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

NMI backtrace for cpu 1

CPU: 1 PID: 27 Comm: khungtaskd Not tainted 6.3.0-rc3-syzkaller-00322-g4bdec23f971b-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
nmi_cpu_backtrace+0x29c/0x350 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x2a4/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
watchdog+0xe16/0x1090 kernel/hung_task.c:379
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0

CPU: 0 PID: 6728 Comm: syz-executor.0 Not tainted 6.3.0-rc3-syzkaller-00322-g4bdec23f971b-dirty #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023

RIP: 0033:0x7f29b98291cc
Code: 01 c2 49 3b 55 08 77 56 8d 55 ff 85 ed 74 35 0f 1f 80 00 00 00 00 48 39 c1 77 1c 49 8b 75 00 49 89 c1 49 29 c9 46 0f b6 0c 0e <45> 84 c9 74 08 44 88 0c 06 49 8b 45 10 48 83 c0 01 49 89 45 10 83
RSP: 002b:00007f29ba575600 EFLAGS: 00000216
RAX: 00000000026526b0 RBX: 00007f29ba575660 RCX: 0000000000000001
RDX: 00000000000000ed RSI: 00007f29b07ff000 RDI: 00007f29ba575700
RBP: 0000000000000102 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 00007f29ba575670 R12: 00007f29ba575670
R13: 00007f29ba575700 R14: 0000000000000001 R15: 0000000000000000
FS: 00007f29ba576700 GS: 0000000000000000


Tested on:

commit: 4bdec23f Merge tag 'hwmon-for-v6.3-rc4' of git://git.k..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=11af0adec80000

kernel config: https://syzkaller.appspot.com/x/.config?x=ea09b0836073ee4
dashboard link: https://syzkaller.appspot.com/bug?extid=8b85865808c8908a0d8c
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=107b0cd5c80000

[Hillf Danton]

On 25 Mar 2023 22:17:44 -0700

> HEAD commit: 4bdec23f971b Merge tag 'hwmon-for-v6.3-rc4' of git://git.k..
> git tree: upstream

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=100b561ec80000

See if sit_i->sentry_lock is acquired with page locked.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 4bdec23f971b

--- x/fs/f2fs/gc.c
+++ y/fs/f2fs/gc.c
@@ -955,7 +955,8 @@ static int check_valid_map(struct f2fs_s
struct seg_entry *sentry;
int ret;

- down_read(&sit_i->sentry_lock);
+ if (!down_read_trylock(&sit_i->sentry_lock))
+ return 0;
sentry = get_seg_entry(sbi, segno);
ret = f2fs_test_bit(offset, sentry->cur_valid_map);
up_read(&sit_i->sentry_lock);

@@ -1813,8 +1814,6 @@ gc_more:
if (ret)
goto stop;
}
- if (has_not_enough_free_secs(sbi, 0, 0))
- gc_type = FG_GC;
}

/* f2fs_balance_fs doesn't need to do BG_GC in critical path. */
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+8b8586...@syzkaller.appspotmail.com

Tested on:

commit: 4bdec23f Merge tag 'hwmon-for-v6.3-rc4' of git://git.k..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

console output: https://syzkaller.appspot.com/x/log.txt?x=1026f0c1c80000

kernel config: https://syzkaller.appspot.com/x/.config?x=ea09b0836073ee4
dashboard link: https://syzkaller.appspot.com/bug?extid=8b85865808c8908a0d8c
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

patch: https://syzkaller.appspot.com/x/patch.diff?x=1488a4b6c80000

Note: testing is done by a robot and is best-effort only.

[syzbot]

syzbot has bisected this issue to:

commit 10d0786b39b3b91c4fbf8c2926e97ab456a4eea1
Author: Jia Yang <jiay...@huawei.com>
Date: Wed Jul 14 07:46:06 2021 +0000

f2fs: Revert "f2fs: Fix indefinite loop in f2fs_gc() v1"

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13426789c80000
start commit: 4bdec23f971b Merge tag 'hwmon-for-v6.3-rc4' of git://git.k..
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=10c26789c80000
console output: https://syzkaller.appspot.com/x/log.txt?x=17426789c80000

kernel config: https://syzkaller.appspot.com/x/.config?x=ea09b0836073ee4
dashboard link: https://syzkaller.appspot.com/bug?extid=8b85865808c8908a0d8c

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1320ef41c80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=100b561ec80000

Reported-by: syzbot+8b8586...@syzkaller.appspotmail.com
Fixes: 10d0786b39b3 ("f2fs: Revert "f2fs: Fix indefinite loop in f2fs_gc() v1"")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection