syzbot


INFO: task hung in prealloc_shrinker

Status: auto-closed as invalid on 2020/08/25 18:04
Reported-by: syzbot+8c888ac478f7b49ea052@syzkaller.appspotmail.com
First crash: 1485d, last: 1431d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in prealloc_shrinker mm 2 896d 903d 0/26 auto-closed as invalid on 2022/01/12 05:23
linux-4.19 INFO: task hung in prealloc_shrinker (2) 1 443d 443d 0/1 upstream: reported on 2023/01/10 08:42

Sample crash report:
INFO: task syz-executor.5:16427 blocked for more than 140 seconds.
      Not tainted 4.19.118-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D28832 16427   6925 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3559
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:589 [inline]
 rwsem_down_write_failed+0x774/0xc30 kernel/locking/rwsem-xadd.c:618
 call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:117
 __down_write arch/x86/include/asm/rwsem.h:142 [inline]
 down_write+0x4f/0x90 kernel/locking/rwsem.c:72
 prealloc_memcg_shrinker mm/vmscan.c:194 [inline]
 prealloc_shrinker+0x16f/0x340 mm/vmscan.c:382
 alloc_super fs/super.c:265 [inline]
 sget_userns+0x773/0xcd0 fs/super.c:519
 mount_ns+0x8e/0x1d0 fs/super.c:1068
 mount_fs+0xa3/0x30c fs/super.c:1261
 vfs_kern_mount.part.0+0x68/0x400 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 kern_mount_data+0x55/0xd0 fs/namespace.c:3255
 mq_init_ns+0x162/0x220 ipc/mqueue.c:1548
 create_ipc_ns ipc/namespace.c:58 [inline]
 copy_ipcs+0x258/0x410 ipc/namespace.c:84
 create_new_namespaces+0x212/0x7c0 kernel/nsproxy.c:87
 copy_namespaces+0x325/0x3c0 kernel/nsproxy.c:165
 copy_process.part.0+0x39ad/0x7a50 kernel/fork.c:1900
 copy_process kernel/fork.c:1694 [inline]
 _do_fork+0x22f/0xf40 kernel/fork.c:2207
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4b662b2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00000000004da840 RCX: 000000000045c829
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 000080218a081fff
RBP: 000000000078bf00 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000076 R14: 00000000004c311e R15: 00007f4b662b36d4
INFO: task syz-executor.5:16435 blocked for more than 140 seconds.
      Not tainted 4.19.118-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5  D29104 16435   6925 0x00000004
Call Trace:
 schedule+0x8d/0x1b0 kernel/sched/core.c:3559
 __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:589 [inline]
 rwsem_down_write_failed+0x774/0xc30 kernel/locking/rwsem-xadd.c:618
 call_rwsem_down_write_failed+0x13/0x20 arch/x86/lib/rwsem.S:117
 __down_write arch/x86/include/asm/rwsem.h:142 [inline]
 down_write+0x4f/0x90 kernel/locking/rwsem.c:72
 prealloc_memcg_shrinker mm/vmscan.c:194 [inline]
 prealloc_shrinker+0x16f/0x340 mm/vmscan.c:382
 alloc_super fs/super.c:265 [inline]
 sget_userns+0x773/0xcd0 fs/super.c:519
 mount_ns+0x8e/0x1d0 fs/super.c:1068
 mount_fs+0xa3/0x30c fs/super.c:1261
 vfs_kern_mount.part.0+0x68/0x400 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 kern_mount_data+0x55/0xd0 fs/namespace.c:3255
 mq_init_ns+0x162/0x220 ipc/mqueue.c:1548
 create_ipc_ns ipc/namespace.c:58 [inline]
 copy_ipcs+0x258/0x410 ipc/namespace.c:84
 create_new_namespaces+0x212/0x7c0 kernel/nsproxy.c:87
 copy_namespaces+0x325/0x3c0 kernel/nsproxy.c:165
 copy_process.part.0+0x39ad/0x7a50 kernel/fork.c:1900
 copy_process kernel/fork.c:1694 [inline]
 _do_fork+0x22f/0xf40 kernel/fork.c:2207
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4b66270c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00000000004da840 RCX: 000000000045c829
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 000080218a081fff
RBP: 000000000078c040 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000076 R14: 00000000004c311e R15: 00007f4b662716d4

Showing all locks held in the system:
1 lock held by khungtaskd/1079:
 #0: 00000000030af0a5 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4440
3 locks held by khugepaged/1086:
1 lock held by in:imklog/6126:
 #0: 00000000dd13fc9b (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:767
2 locks held by syz-executor.5/16427:
 #0: 0000000036fc1572 (&type->s_umount_key#18/1){+.+.}, at: alloc_super fs/super.c:226 [inline]
 #0: 0000000036fc1572 (&type->s_umount_key#18/1){+.+.}, at: sget_userns+0x1fc/0xcd0 fs/super.c:519
 #1: 000000000e2f2c15 (shrinker_rwsem){++++}, at: prealloc_memcg_shrinker mm/vmscan.c:194 [inline]
 #1: 000000000e2f2c15 (shrinker_rwsem){++++}, at: prealloc_shrinker+0x16f/0x340 mm/vmscan.c:382
2 locks held by syz-executor.5/16435:
 #0: 000000005db7b49d (&type->s_umount_key#18/1){+.+.}, at: alloc_super fs/super.c:226 [inline]
 #0: 000000005db7b49d (&type->s_umount_key#18/1){+.+.}, at: sget_userns+0x1fc/0xcd0 fs/super.c:519
 #1: 000000000e2f2c15 (shrinker_rwsem){++++}, at: prealloc_memcg_shrinker mm/vmscan.c:194 [inline]
 #1: 000000000e2f2c15 (shrinker_rwsem){++++}, at: prealloc_shrinker+0x16f/0x340 mm/vmscan.c:382

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

NMI backtrace for cpu 0
CPU: 0 PID: 1079 Comm: khungtaskd Not tainted 4.19.118-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1a6/0x1eb lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
 watchdog+0x962/0xe40 kernel/hung_task.c:287
 kthread+0x34a/0x420 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 7136 Comm: kworker/u4:4 Not tainted 4.19.118-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_nc_worker
RIP: 0010:__lock_acquire+0x24a/0x49c0 kernel/locking/lockdep.c:3321
Code: 00 be 04 00 00 00 44 89 84 24 80 00 00 00 48 89 84 24 88 00 00 00 e8 a5 16 4e 00 48 8b 84 24 88 00 00 00 f0 ff 80 38 01 00 00 <49> 8d b6 80 08 00 00 44 8b 84 24 80 00 00 00 48 ba 00 00 00 00 00
RSP: 0000:ffff888218ad7a20 EFLAGS: 00000012
RAX: ffffffff8b474c30 RBX: 0000000000000000 RCX: ffffffff814f545b
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8b474d68
RBP: ffff888218ad7be8 R08: 0000000000000001 R09: fffffbfff168e9ae
R10: fffffbfff168e9ad R11: ffffffff8b474d6b R12: 0000000000000000
R13: 0000000000000000 R14: ffff888212eaa6c0 R15: ffff888048b86920
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c427ad1fe0 CR3: 000000005e080000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 lock_acquire+0x170/0x400 kernel/locking/lockdep.c:3907
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:168
 spin_lock_bh include/linux/spinlock.h:334 [inline]
 batadv_nc_purge_paths+0xdf/0x3b0 net/batman-adv/network-coding.c:453
 batadv_nc_worker+0x299/0x760 net/batman-adv/network-coding.c:731
 process_one_work+0x91f/0x1640 kernel/workqueue.c:2155
 worker_thread+0x96/0xe20 kernel/workqueue.c:2298
 kthread+0x34a/0x420 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/04/27 18:04 linux-4.19.y 7edd66cf6167 0ce7569e .config console log report ci2-linux-4-19
2020/03/04 07:49 linux-4.19.y a083db76118d 1f73b64b .config console log report ci2-linux-4-19
* Struck through repros no longer work on HEAD.