syzbot

INFO: task syz-executor235:4161 blocked for more than 143 seconds.
      Not tainted 5.15.179-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor235 state:D stack:25176 pid: 4161 ppid:  4159 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5029 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6375
 schedule+0x11b/0x1f0 kernel/sched/core.c:6458
 wb_wait_for_completion+0x164/0x290 fs/fs-writeback.c:191
 __writeback_inodes_sb_nr+0x2ce/0x370 fs/fs-writeback.c:2684
 sync_filesystem+0xa0/0x220 fs/sync.c:54
 generic_shutdown_super+0x6b/0x310 fs/super.c:448
 kill_block_super+0x7a/0xe0 fs/super.c:1427
 kill_f2fs_super+0x2ff/0x3c0 fs/f2fs/super.c:4538
 deactivate_locked_super+0xa0/0x110 fs/super.c:335
 cleanup_mnt+0x44e/0x500 fs/namespace.c:1143
 task_work_run+0x129/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f4947b804c7
RSP: 002b:00007fff681a2578 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f4947b804c7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff681a2630
RBP: 00007fff681a2630 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000206 R12: 00007fff681a36a0
R13: 00005555790b56c0 R14: 431bde82d7b634db R15: 00007fff681a36c0
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8cb1f4e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
5 locks held by kworker/u4:4/1439:
2 locks held by getty/3929:
 #0: ffff88807ec19098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cd62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158
1 lock held by syz-executor235/4161:
 #0: ffff8880290620e0 (&type->s_umount_key#43){+.+.}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:365

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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:212 [inline]
 watchdog+0xe72/0xeb0 kernel/hung_task.c:369
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 1439 Comm: kworker/u4:4 Not tainted 5.15.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:0)
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:-1 [inline]
RIP: 0010:unwind_next_frame+0x143e/0x1fa0 arch/x86/kernel/unwind_orc.c:616
Code: 0f 85 78 02 00 00 c6 05 82 36 be 0c 01 48 c7 c7 e0 94 a8 8a e9 0e fa ff ff bf 01 00 00 00 e8 29 d2 1e 00 65 8b 0d 9a a2 c9 7e <b0> 01 85 c9 0f 85 a1 02 00 00 e8 63 bf c7 ff e9 97 02 00 00 80 3d
RSP: 0018:ffffc90005606248 EFLAGS: 00000297
RAX: 0000000080000001 RBX: ffffc90005606310 RCX: 0000000080000000
RDX: dffffc0000000000 RSI: ffffc900056079b0 RDI: 0000000000000001
RBP: ffffc900056079c0 R08: ffffc900056079b0 R09: ffffc90005606350
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffffffff1d1cefe
R13: 1ffffffff1d1cefe R14: ffffc90005600000 R15: ffffc90005606300
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe07b76d7c CR3: 000000002aff1000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 arch_stack_walk+0x10d/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x8e/0xc0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x53/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3220 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0xf3/0x280 mm/slub.c:3233
 mempool_alloc+0x17f/0x590 mm/mempool.c:393
 bio_alloc_bioset+0x132/0x8c0 block/bio.c:466
 f2fs_grab_read_bio+0x9f/0x720 fs/f2fs/data.c:990
 f2fs_submit_page_read+0xb8/0x2c0 fs/f2fs/data.c:1035
 f2fs_get_read_data_page+0x455/0x6b0 fs/f2fs/data.c:1224
 f2fs_get_lock_data_page+0x54/0x250 fs/f2fs/data.c:1271
 move_data_page fs/f2fs/gc.c:1336 [inline]
 gc_data_segment fs/f2fs/gc.c:1547 [inline]
 do_garbage_collect+0x3645/0x7540 fs/f2fs/gc.c:1671
 f2fs_gc+0x9d2/0x1c30 fs/f2fs/gc.c:1765
 f2fs_balance_fs+0x4e8/0x6a0 fs/f2fs/segment.c:529
 f2fs_write_inode+0x4be/0x660 fs/f2fs/inode.c:738
 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
 wb_writeback+0x451/0xc50 fs/fs-writeback.c:2104
 wb_do_writeback fs/fs-writeback.c:2247 [inline]
 wb_workfn+0x46c/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:287
 </TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.327 msecs