syzbot


INFO: task hung in find_inode_fast (2)

Status: fixed on 2024/01/30 15:47
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+adfd362e7719c02b3015@syzkaller.appspotmail.com
Fix commit: 6f861765464f fs: Block writes to mounted block devices
First crash: 368d, last: 192d
Cause bisection: introduced by (bisect log) [merge commit]:
commit 1b722407a13b7f8658d2e26917791f32805980a2
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu Jun 29 18:00:17 2023 +0000

  Merge tag 'drm-next-2023-06-29' of git://anongit.freedesktop.org/drm/drm

Crash: INFO: task hung in find_inode_fast (log)
Repro: C syz .config
  
Fix bisection: fixed by (bisect log) :
commit 6f861765464f43a71462d52026fbddfc858239a5
Author: Jan Kara <jack@suse.cz>
Date: Wed Nov 1 17:43:10 2023 +0000

  fs: Block writes to mounted block devices

  
Discussions (3)
Title Replies (including bot) Last reply
[syzbot] [ext4?] INFO: task hung in find_inode_fast (2) 1 (3) 2024/01/16 15:57
[syzbot] Monthly ext4 report (Oct 2023) 0 (1) 2023/10/09 09:23
[syzbot] Monthly ext4 report (Aug 2023) 0 (1) 2023/08/07 07:27
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in find_inode_fast 3 409d 427d 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 383d 532d 22/27 fixed on 2023/06/08 14:41
Last patch testing requests (3)
Created Duration User Patch Repo Result
2023/12/14 09:14 43m retest repro upstream report log
2023/09/24 13:35 21m retest repro upstream report log
2023/08/29 03:02 18m retest repro upstream report log
Fix bisection attempts (3)
Created Duration User Patch Repo Result
2024/01/16 08:25 7h10m bisect fix upstream job log (1)
2023/11/30 06:34 2h38m bisect fix upstream job log (0) log
2023/10/25 14:38 2h56m bisect fix upstream job log (0) log

Sample crash report:
INFO: task syz-executor173:7462 blocked for more than 143 seconds.
      Not tainted 6.4.0-syzkaller-12454-g1c7873e33645 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor173 state:D stack:25544 pid:7462  ppid:5046   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1873/0x48f0 kernel/sched/core.c:6710
 schedule+0xc3/0x180 kernel/sched/core.c:6786
 __wait_on_freeing_inode fs/inode.c:2240 [inline]
 find_inode_fast+0x319/0x450 fs/inode.c:950
 iget_locked+0xcb/0x830 fs/inode.c:1317
 __ext4_iget+0x261/0x3f30 fs/ext4/inode.c:4670
 ext4_xattr_inode_cache_find fs/ext4/xattr.c:1542 [inline]
 ext4_xattr_inode_lookup_create fs/ext4/xattr.c:1577 [inline]
 ext4_xattr_set_entry+0x219f/0x3e80 fs/ext4/xattr.c:1719
 ext4_xattr_block_set+0xb12/0x3630 fs/ext4/xattr.c:2025
 ext4_xattr_set_handle+0xcd4/0x15c0 fs/ext4/xattr.c:2442
 ext4_xattr_set+0x241/0x3d0 fs/ext4/xattr.c:2544
 __vfs_setxattr+0x460/0x4a0 fs/xattr.c:201
 __vfs_setxattr_noperm+0x12e/0x5e0 fs/xattr.c:235
 vfs_setxattr+0x221/0x420 fs/xattr.c:322
 do_setxattr fs/xattr.c:630 [inline]
 setxattr+0x25d/0x2f0 fs/xattr.c:653
 path_setxattr+0x1c0/0x2a0 fs/xattr.c:672
 __do_sys_setxattr fs/xattr.c:688 [inline]
 __se_sys_setxattr fs/xattr.c:684 [inline]
 __x64_sys_setxattr+0xbb/0xd0 fs/xattr.c:684
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f9b8cd80509
RSP: 002b:00007f9b841472f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f9b8ce0c550 RCX: 00007f9b8cd80509
RDX: 00000000200005c0 RSI: 0000000020000180 RDI: 00000000200000c0
RBP: 0030656c69662f2e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000002000 R11: 0000000000000246 R12: 00007f9b8cdd2360
R13: 66763d746d66716a R14: 2f30656c69662f2e R15: 00007f9b8ce0c558
 </TASK>
INFO: task syz-executor173:7468 blocked for more than 143 seconds.
      Not tainted 6.4.0-syzkaller-12454-g1c7873e33645 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor173 state:D stack:25768 pid:7468  ppid:5046   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1873/0x48f0 kernel/sched/core.c:6710
 schedule+0xc3/0x180 kernel/sched/core.c:6786
 mb_cache_entry_wait_unused+0x166/0x250 fs/mbcache.c:148
 ext4_evict_ea_inode+0x14a/0x2f0 fs/ext4/xattr.c:480
 ext4_evict_inode+0x184/0xf20 fs/ext4/inode.c:180
 evict+0x2a4/0x620 fs/inode.c:665
 ext4_xattr_set_entry+0x13d4/0x3e80 fs/ext4/xattr.c:1856
 ext4_xattr_block_set+0x69c/0x3630 fs/ext4/xattr.c:1956
 ext4_xattr_set_handle+0xcd4/0x15c0 fs/ext4/xattr.c:2442
 ext4_xattr_set+0x241/0x3d0 fs/ext4/xattr.c:2544
 __vfs_setxattr+0x460/0x4a0 fs/xattr.c:201
 __vfs_setxattr_noperm+0x12e/0x5e0 fs/xattr.c:235
 vfs_setxattr+0x221/0x420 fs/xattr.c:322
 do_setxattr fs/xattr.c:630 [inline]
 setxattr+0x25d/0x2f0 fs/xattr.c:653
 path_setxattr+0x1c0/0x2a0 fs/xattr.c:672
 __do_sys_setxattr fs/xattr.c:688 [inline]
 __se_sys_setxattr fs/xattr.c:684 [inline]
 __x64_sys_setxattr+0xbb/0xd0 fs/xattr.c:684
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f9b8cd80509
RSP: 002b:00007f9b841262f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000bc
RAX: ffffffffffffffda RBX: 00007f9b8ce0c560 RCX: 00007f9b8cd80509
RDX: 0000000000000000 RSI: 0000000020000200 RDI: 00000000200001c0
RBP: 0030656c69662f2e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9b8cdd2360
R13: 66763d746d66716a R14: 2f30656c69662f2e R15: 00007f9b8ce0c568
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/13:
 #0: ffffffff8d328af0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:522
1 lock held by rcu_tasks_trace/14:
 #0: ffffffff8d328eb0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xd20 kernel/rcu/tasks.h:522
1 lock held by khungtaskd/28:
 #0: ffffffff8d328920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
3 locks held by kworker/1:2/2094:
 #0: ffff888012870d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7e3/0x12c0 kernel/workqueue.c:2569
 #1: ffffc9000786fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x82b/0x12c0 kernel/workqueue.c:2571
 #2: ffffffff8d32dfb8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:325 [inline]
 #2: ffffffff8d32dfb8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x46c/0x890 kernel/rcu/tree_exp.h:992
3 locks held by kworker/0:3/4759:
 #0: ffff888012870d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7e3/0x12c0 kernel/workqueue.c:2569
 #1: ffffc9000379fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x82b/0x12c0 kernel/workqueue.c:2571
 #2: ffffffff8d32dfb8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:293 [inline]
 #2: ffffffff8d32dfb8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a3/0x890 kernel/rcu/tree_exp.h:992
2 locks held by getty/4772:
 #0: ffff88802d3c2098
 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900015b02f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b1/0x1dc0 drivers/tty/n_tty.c:2187
1 lock held by udevd/5050:
2 locks held by kworker/0:2/5052:
 #0: ffff888012870d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7e3/0x12c0 kernel/workqueue.c:2569
 #1: ffffc90003c0fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x82b/0x12c0 kernel/workqueue.c:2571
2 locks held by kworker/1:3/5060:
 #0: ffff888012870d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7e3/0x12c0 kernel/workqueue.c:2569
 #1: ffffc90003c9fd20 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x82b/0x12c0 kernel/workqueue.c:2571
1 lock held by udevd/5105:
2 locks held by kworker/0:4/5115:
 #0: ffff888012872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7e3/0x12c0 kernel/workqueue.c:2569
 #1: ffffc90003e6fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x82b/0x12c0 kernel/workqueue.c:2571
3 locks held by syz-executor173/7462:
 #0: ffff8880220f2410 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:403
 #1: ffff8880783cf200 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: inode_lock include/linux/fs.h:771 [inline]
 #1: ffff8880783cf200 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: vfs_setxattr+0x1e1/0x420 fs/xattr.c:321
 #2: ffff8880783ceec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff8880783ceec8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x274/0x15c0 fs/ext4/xattr.c:2357
3 locks held by syz-executor173/7468:
 #0: ffff8880220f2410 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:403
 #1: ffff88806aed8400 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock include/linux/fs.h:771 [inline]
 #1: ffff88806aed8400 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: vfs_setxattr+0x1e1/0x420 fs/xattr.c:321
 #2: ffff88806aed80c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_write_lock_xattr fs/ext4/xattr.h:155 [inline]
 #2: ffff88806aed80c8 (&ei->xattr_sem){++++}-{3:3}, at: ext4_xattr_set_handle+0x274/0x15c0 fs/ext4/xattr.c:2357

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted 6.4.0-syzkaller-12454-g1c7873e33645 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x498/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x187/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xec2/0xf00 kernel/hung_task.c:379
 kthread+0x2b8/0x350 kernel/kthread.c:389
 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 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline]
NMI backtrace for cpu 1 skipped: idling at __intel_idle_hlt drivers/idle/intel_idle.c:205 [inline]
NMI backtrace for cpu 1 skipped: idling at intel_idle_hlt+0x15/0x20 drivers/idle/intel_idle.c:224

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/09 16:20 upstream 1c7873e33645 668cb1fa .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-smack-root INFO: task hung in find_inode_fast
2023/09/10 11:08 upstream 2a5a4326e583 6654cf89 .config strace log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-selinux-root INFO: task hung in find_inode_fast
2023/07/27 11:58 upstream 0a8db05b571a 41fe1bae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in find_inode_fast
2023/07/26 17:07 upstream 18b44bc5a672 41fe1bae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in find_inode_fast
2023/07/25 01:17 upstream 0b5547c51827 9a0ddda3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in find_inode_fast
2023/07/19 00:52 upstream 74f1456c4a5f 022df2bb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in find_inode_fast
2023/07/18 15:42 upstream fdf0eaf11452 022df2bb .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in find_inode_fast
2023/07/06 01:34 upstream 6cd06ab12d1a ba5dba36 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: task hung in find_inode_fast
2023/06/21 00:03 upstream 99ec1ed7c2ed 09ffe269 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root INFO: task hung in find_inode_fast
2023/07/27 05:23 linux-next 0ba5d0720577 41fe1bae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in find_inode_fast
* Struck through repros no longer work on HEAD.