syzbot


INFO: task hung in netfs_retry_writes

Status: upstream: reported C repro on 2025/01/16 02:33
Subsystems: netfs
[Documentation on labels]
Reported-by: syzbot+666a9cb4c41986207cdf@syzkaller.appspotmail.com
First crash: 32d, last: 12d
Cause bisection: introduced by (bisect log) [merge commit]:
commit e59ca319069a020548148444c69a621db4e3c233
Author: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Mon Jan 6 23:54:06 2025 +0000

  Merge branch 'xtensa-for-next' of git://github.com/jcmvbkbc/linux-xtensa.git

Crash: BUG: unable to handle kernel NULL pointer dereference in iter_file_splice_write (log)
Repro: C syz .config
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [netfs?] INFO: task hung in netfs_retry_writes 0 (1) 2025/01/16 02:33

Sample crash report:
INFO: task kworker/u8:0:11 blocked for more than 143 seconds.
      Not tainted 6.13.0-syzkaller-00603-g3d3a9c8b89d4 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0    state:D stack:22912 pid:11    tgid:11    ppid:2      flags:0x00004000
Workqueue: events_unbound netfs_write_collection_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0xe58/0x5ad0 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6848
 bit_wait+0x15/0xe0 kernel/sched/wait_bit.c:237
 __wait_on_bit+0x62/0x180 kernel/sched/wait_bit.c:49
 out_of_line_wait_on_bit+0xda/0x110 kernel/sched/wait_bit.c:64
 wait_on_bit include/linux/wait_bit.h:77 [inline]
 netfs_retry_writes+0x2fa/0x1a00 fs/netfs/write_retry.c:215
 netfs_collect_write_results fs/netfs/write_collect.c:352 [inline]
 netfs_write_collection_worker+0x23de/0x37c0 fs/netfs/write_collect.c:374
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3317 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u8:0/11:
 #0: ffff88801b081148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3211
 #1: ffffc90000107d80 ((work_completion)(&rreq->work)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3212
1 lock held by khungtaskd/30:
 #0: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1bbcc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x7f/0x390 kernel/locking/lockdep.c:6744
6 locks held by kworker/u8:6/1333:
2 locks held by getty/5569:
 #0: ffff888036ee20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0xfba/0x1480 drivers/tty/n_tty.c:2211
2 locks held by syz-executor885/5832:
 #0: ffff888066606420 (sb_writers#10){.+.+}-{0:0}, at: splice_direct_to_actor+0x346/0xa40 fs/splice.c:1108
 #1: ffff888078830148 (&sb->s_type->i_mutex_key#15){++++}-{4:4}, at: netfs_start_io_direct+0x116/0x260 fs/netfs/locking.c:188

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.13.0-syzkaller-00603-g3d3a9c8b89d4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:234 [inline]
 watchdog+0xf14/0x1240 kernel/hung_task.c:397
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 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: 1333 Comm: kworker/u8:6 Not tainted 6.13.0-syzkaller-00603-g3d3a9c8b89d4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:kasan_check_range+0x0/0x1a0 mm/kasan/generic.c:188
Code: e6 d4 ff ff 89 43 08 5b 5d 41 5c c3 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <66> 0f 1f 00 48 85 f6 0f 84 50 01 00 00 48 89 f8 41 54 44 0f b6 c2
RSP: 0018:ffffc9000480f978 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00fff00000002000 RCX: ffffffff813e1e94
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffea000007c980
RBP: ffffffff81f26677 R08: 0000000000000007 R09: ffffffffffffffff
R10: 00fff00000002000 R11: 0000000000000006 R12: 0000000000000678
R13: ffffea000007c980 R14: 0000000000000005 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005642d4949028 CR3: 000000000df7e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 PageReserved include/linux/page-flags.h:533 [inline]
 __text_poke+0x164/0xca0 arch/x86/kernel/alternative.c:1909
 text_poke_bp_batch+0x3e0/0x760 arch/x86/kernel/alternative.c:2346
 text_poke_flush arch/x86/kernel/alternative.c:2515 [inline]
 text_poke_flush arch/x86/kernel/alternative.c:2512 [inline]
 text_poke_finish+0x30/0x40 arch/x86/kernel/alternative.c:2522
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 jump_label_update+0x1d7/0x400 kernel/jump_label.c:920
 static_key_enable_cpuslocked+0x1b7/0x270 kernel/jump_label.c:210
 static_key_enable+0x1a/0x20 kernel/jump_label.c:223
 toggle_allocation_gate mm/kfence/core.c:849 [inline]
 toggle_allocation_gate+0xfc/0x260 mm/kfence/core.c:841
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3317 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Crashes (45):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/21 14:20 upstream 3d3a9c8b89d4 6e87cfa2 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/21 08:08 upstream 100ceb4817a2 6e87cfa2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/21 03:45 upstream 100ceb4817a2 6e87cfa2 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/12 02:23 linux-next 7b4b9bf203da 6dbc6a9b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/27 05:45 upstream c2da8b3f914f 9fbd772e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/26 01:56 upstream 0f8e26b38d7a 9fbd772e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/21 09:32 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/21 09:32 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/21 09:08 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/21 09:07 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/21 08:36 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/21 08:27 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/21 08:26 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/21 08:13 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/21 08:12 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/21 08:10 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/21 07:41 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/21 07:22 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/21 07:19 upstream 3d3a9c8b89d4 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in netfs_retry_writes
2025/01/20 22:35 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 22:16 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 22:01 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 21:51 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 21:38 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 21:30 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 21:25 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 21:23 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/20 21:18 upstream 100ceb4817a2 6e87cfa2 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in netfs_retry_writes
2025/01/13 03:00 linux-next 7b4b9bf203da 6dbc6a9b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/12 23:35 linux-next 7b4b9bf203da 6dbc6a9b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/11 22:37 linux-next 7b4b9bf203da 6dbc6a9b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/11 09:47 linux-next 7b4b9bf203da 6dbc6a9b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/11 09:46 linux-next 7b4b9bf203da 6dbc6a9b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/10 22:25 linux-next 7b4b9bf203da 67d7ec0a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/08 22:09 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/08 01:29 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 12:27 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 11:21 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 11:08 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 10:40 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 10:37 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 10:27 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 10:24 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
2025/01/07 10:23 linux-next 7b4b9bf203da f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in netfs_retry_writes
* Struck through repros no longer work on HEAD.