syzbot


INFO: task hung in find_inode_fast (3)

Status: upstream: reported on 2025/04/02 13:08
Reported-by: syzbot+92f25a446954700071a2@syzkaller.appspotmail.com
First crash: 11d, last: 11d
Similar bugs (7)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in find_inode_fast (4) ext4 syz error 8 20d 112d 0/28 upstream: reported syz repro on 2024/12/23 01:23
upstream INFO: task hung in find_inode_fast (3) ext4 7 244d 342d 0/28 auto-obsoleted due to no activity on 2024/11/10 11:05
upstream INFO: task hung in find_inode_fast (2) ext4 C unreliable done 10 486d 640d 25/28 fixed on 2024/01/30 15:47
linux-5.15 INFO: task hung in find_inode_fast 3 704d 722d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:07
upstream INFO: task hung in find_inode_fast ext4 C error 28 678d 827d 22/28 fixed on 2023/06/08 14:41
linux-6.1 INFO: task hung in find_inode_fast 1 144d 144d 0/3 auto-obsoleted due to no activity on 2025/02/28 14:47
linux-5.15 INFO: task hung in find_inode_fast (2) 1 163d 163d 0/3 auto-obsoleted due to no activity on 2025/02/09 11:15

Sample crash report:
INFO: task syz.7.711:7779 blocked for more than 144 seconds.
      Not tainted 5.15.179-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.711       state:D stack:23840 pid: 7779 ppid:  5650 flags:0x00004004
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
 __wait_on_freeing_inode fs/inode.c:2139 [inline]
 find_inode_fast+0x315/0x450 fs/inode.c:933
 iget_locked+0xb2/0x7f0 fs/inode.c:1295
 __ext4_iget+0x25d/0x3f00 fs/ext4/inode.c:4648
 ext4_xattr_inode_cache_find fs/ext4/xattr.c:1499 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1534 [inline]
 ext4_xattr_set_entry+0x22e1/0x4130 fs/ext4/xattr.c:1675
 ext4_xattr_block_set+0xb10/0x36a0 fs/ext4/xattr.c:1995
 ext4_xattr_set_handle+0xdac/0x1560 fs/ext4/xattr.c:2412
 ext4_xattr_set+0x26e/0x3d0 fs/ext4/xattr.c:2513
 __vfs_setxattr+0x3e7/0x420 fs/xattr.c:182
 __vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
 vfs_setxattr+0x21d/0x420 fs/xattr.c:303
 do_setxattr fs/xattr.c:588 [inline]
 setxattr+0x27e/0x2e0 fs/xattr.c:611
 path_setxattr+0x1bc/0x2a0 fs/xattr.c:630
 __do_sys_setxattr fs/xattr.c:646 [inline]
 __se_sys_setxattr fs/xattr.c:642 [inline]
 __x64_sys_setxattr+0xb7/0xd0 fs/xattr.c:642
 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: 0033:0x7fa1d6233169
RSP: 002b:00007fa1d407b038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007fa1d644c080 RCX: 00007fa1d6233169
RDX: 0000200000001400 RSI: 00002000000001c0 RDI: 0000200000000200
RBP: 00007fa1d62b42a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000835 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa1d644c080 R15: 00007ffd41a28698
 </TASK>
INFO: task syz.7.711:7785 blocked for more than 145 seconds.
      Not tainted 5.15.179-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.711       state:D stack:24144 pid: 7785 ppid:  5650 flags:0x00004004
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
 mb_cache_entry_wait_unused+0x164/0x240 fs/mbcache.c:148
 ext4_evict_ea_inode+0x146/0x2e0 fs/ext4/xattr.c:444
 ext4_evict_inode+0x17d/0x1100 fs/ext4/inode.c:183
 evict+0x529/0x930 fs/inode.c:647
 ext4_xattr_set_entry+0x1d88/0x4130 fs/ext4/xattr.c:1826
 ext4_xattr_block_set+0x69a/0x36a0 fs/ext4/xattr.c:1926
 ext4_xattr_set_handle+0x104c/0x1560 fs/ext4/xattr.c:2403
 ext4_xattr_set+0x26e/0x3d0 fs/ext4/xattr.c:2513
 __vfs_setxattr+0x3e7/0x420 fs/xattr.c:182
 __vfs_setxattr_noperm+0x12a/0x5e0 fs/xattr.c:216
 vfs_setxattr+0x21d/0x420 fs/xattr.c:303
 do_setxattr fs/xattr.c:588 [inline]
 setxattr+0x27e/0x2e0 fs/xattr.c:611
 path_setxattr+0x1bc/0x2a0 fs/xattr.c:630
 __do_sys_setxattr fs/xattr.c:646 [inline]
 __se_sys_setxattr fs/xattr.c:642 [inline]
 __x64_sys_setxattr+0xb7/0xd0 fs/xattr.c:642
 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: 0033:0x7fa1d6233169
RSP: 002b:00007fa1d405a038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007fa1d644c160 RCX: 00007fa1d6233169
RDX: 0000000000000000 RSI: 0000200000000100 RDI: 00002000000000c0
RBP: 00007fa1d62b42a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa1d644c160 R15: 00007ffd41a28698
 </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
6 locks held by kworker/u4:4/3032:
 #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffff8880b8f27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x53d/0x810 kernel/sched/psi.c:891
 #2: ffff8880b8f27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_enqueue kernel/sched/stats.h:102 [inline]
 #2: ffff8880b8f27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: enqueue_task+0x28d/0x2e0 kernel/sched/core.c:1972
 #3: ffff8880b8f3a318 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
 #4: ffff8880b8f27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_enqueue kernel/sched/stats.h:102 [inline]
 #4: ffff8880b8f27848 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: enqueue_task+0x28d/0x2e0 kernel/sched/core.c:1972
 #5: ffff8880b8f28098 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x120/0x260 kernel/time/timer.c:946
2 locks held by getty/3929:
 #0: ffff88802c98f098 (&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
2 locks held by syz-executor/4169:
 #0: ffff888020c3fd18 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfb/0x790 block/bdev.c:915
 #1: ffff888147522468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1365
2 locks held by syz-executor/4170:
 #0: ffff88804ff380e0 (&type->s_umount_key#71){+.+.}-{3:3}, at: deactivate_super+0xa9/0xe0 fs/super.c:365
 #1: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #1: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x280/0x740 kernel/rcu/tree_exp.h:845
3 locks held by syz.7.711/7779:
 #0: ffff88807abb6460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:377
 #1: ffff8880613e35c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff8880613e35c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: vfs_setxattr+0x1dd/0x420 fs/xattr.c:302
 #2: ffff8880613e32a0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff8880613e32a0 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x270/0x1560 fs/ext4/xattr.c:2327
3 locks held by syz.7.711/7785:
 #0: ffff88807abb6460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:377
 #1: ffff88805c505da8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #1: ffff88805c505da8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: vfs_setxattr+0x1dd/0x420 fs/xattr.c:302
 #2: ffff88805c505a80 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff88805c505a80 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x270/0x1560 fs/ext4/xattr.c:2327
2 locks held by kworker/1:10/7859:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc90002f8fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
3 locks held by kworker/1:17/7965:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc9000359fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #2: ffffffff8cb23aa8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x350/0x740 kernel/rcu/tree_exp.h:845
2 locks held by syz.0.1049/9112:
2 locks held by syz.0.1070/9195:
 #0: ffff8880610f2610 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #0: ffff8880610f2610 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:648 [inline]
 #0: ffff8880610f2610 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x98/0x230 net/socket.c:1336
 #1: ffff888075f87120 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1684 [inline]
 #1: ffff888075f87120 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pptp_release+0x4e/0x2f0 drivers/net/ppp/pptp.c:508

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

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: 3535 Comm: klogd Not tainted 5.15.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:__lock_acquire+0x423/0x1ff0 kernel/locking/lockdep.c:4954
Code: c1 e3 0d 44 09 e3 8b 44 24 60 c1 e0 0f 0f b7 c0 09 d8 8b 74 24 54 83 e6 03 c1 e6 10 09 c6 8b 44 24 2c 83 e0 01 c1 e0 12 31 c9 <83> 7c 24 70 00 0f 95 c1 c1 e1 13 41 c1 e7 14 41 09 cf 41 09 c7 41
RSP: 0018:ffffc90002cdf820 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000015 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000020015 RDI: ffff88807ddfe414
RBP: ffff88807ddfd940 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000015
R13: 0000000000000000 R14: 1ffff1100fbbfc8a R15: 0000000000000000
FS:  00007ff81e53c380(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb39357f178 CR3: 000000001f025000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:312
 rcu_read_lock include/linux/rcupdate.h:739 [inline]
 pfn_valid include/linux/mmzone.h:1500 [inline]
 __virt_addr_valid+0x176/0x460 arch/x86/mm/physaddr.c:65
 check_heap_object mm/usercopy.c:228 [inline]
 __check_object_size+0xab/0x410 mm/usercopy.c:286
 check_object_size include/linux/thread_info.h:199 [inline]
 check_copy_size include/linux/thread_info.h:232 [inline]
 copy_to_user include/linux/uaccess.h:199 [inline]
 syslog_print+0x7b0/0x9b0 kernel/printk/printk.c:1577
 do_syslog+0x842/0x940 kernel/printk/printk.c:1679
 __do_sys_syslog kernel/printk/printk.c:1771 [inline]
 __se_sys_syslog kernel/printk/printk.c:1769 [inline]
 __x64_sys_syslog+0x78/0x90 kernel/printk/printk.c:1769
 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: 0033:0x7ff81e69dfa7
Code: 73 01 c3 48 8b 0d 81 ce 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 67 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 51 ce 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007fffecc1f598 EFLAGS: 00000206 ORIG_RAX: 0000000000000067
RAX: ffffffffffffffda RBX: 00007ff81e83c4a0 RCX: 00007ff81e69dfa7
RDX: 00000000000003ff RSI: 00007ff81e83c4a0 RDI: 0000000000000002
RBP: 0000000000000000 R08: 0000000000000007 R09: 7723f180e8808648
R10: 0000000000004000 R11: 0000000000000206 R12: 00007ff81e83c4a0
R13: 00007ff81e82c212 R14: 00007ff81e83c883 R15: 00007ff81e83c883
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/02 13:07 linux-5.15.y 0c935c049b5c c799dfdd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in find_inode_fast
* Struck through repros no longer work on HEAD.