BUG: soft lockup in d_walk

Status: fixed on 2018/09/05 09:58
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+a5a7e1ac68e34c62099d@syzkaller.appspotmail.com
Fix commit: 4fb48871409e restore cond_resched() in shrink_dcache_parent()
First crash: 3012d, last: 2967d

Sample crash report:
watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [syz-executor146:4513]
Modules linked in:
irq event stamp: 21997208
hardirqs last  enabled at (21997207): [<ffffffff81c6500f>] seqcount_lockdep_reader_access include/linux/seqlock.h:83 [inline]
hardirqs last  enabled at (21997207): [<ffffffff81c6500f>] read_seqcount_begin include/linux/seqlock.h:164 [inline]
hardirqs last  enabled at (21997207): [<ffffffff81c6500f>] read_seqbegin include/linux/seqlock.h:433 [inline]
hardirqs last  enabled at (21997207): [<ffffffff81c6500f>] read_seqbegin_or_lock include/linux/seqlock.h:529 [inline]
hardirqs last  enabled at (21997207): [<ffffffff81c6500f>] d_walk+0x80f/0xc80 fs/dcache.c:1248
hardirqs last disabled at (21997208): [<ffffffff87800905>] interrupt_entry+0xb5/0xf0 arch/x86/entry/entry_64.S:625
softirqs last  enabled at (21996468): [<ffffffff87a00778>] __do_softirq+0x778/0xaf5 kernel/softirq.c:311
softirqs last disabled at (21996461): [<ffffffff81475281>] invoke_softirq kernel/softirq.c:365 [inline]
softirqs last disabled at (21996461): [<ffffffff81475281>] irq_exit+0x1d1/0x200 kernel/softirq.c:405
CPU: 0 PID: 4513 Comm: syz-executor146 Not tainted 4.17.0-rc5+ #57
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__preempt_count_sub arch/x86/include/asm/preempt.h:81 [inline]
RIP: 0010:rcu_is_watching+0xf0/0x140 kernel/rcu/tree.c:1076
RSP: 0018:ffff8801acdbf958 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: 000000000000bb15 RBX: ffffed00359b7f2c RCX: 1ffff100359b7f30
RDX: dffffc0000000000 RSI: 0000000000000004 RDI: ffff8801dae23610
RBP: ffff8801acdbf9e8 R08: ffffed003b5c46c3 R09: ffffed003b5c46c2
R10: ffffed003b5c46c2 R11: ffff8801dae23613 R12: 1ffff100359b7f30
R13: ffff8801dae23610 R14: ffff8801acdbf9c0 R15: dffffc0000000000
FS:  0000000001da9880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001dba918 CR3: 00000001aebd5000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 rcu_read_unlock include/linux/rcupdate.h:684 [inline]
 d_walk+0xbd1/0xc80 fs/dcache.c:1327
 shrink_dcache_parent+0x179/0x230 fs/dcache.c:1486
 vfs_rmdir+0x202/0x470 fs/namei.c:3850
 do_rmdir+0x523/0x610 fs/namei.c:3911
 __do_sys_rmdir fs/namei.c:3929 [inline]
 __se_sys_rmdir fs/namei.c:3927 [inline]
 __x64_sys_rmdir+0x36/0x40 fs/namei.c:3927
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446967
RSP: 002b:00007fffb1134178 EFLAGS: 00000207 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 0000000000446967
RDX: 0000000000000000 RSI: 00000000006db898 RDI: 00007fffb1135260
RBP: 00007fffb1135260 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000005 R11: 0000000000000207 R12: 0000000001daa8a0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: d2 74 05 80 fa 03 7e 43 49 c1 ec 03 41 89 46 c0 48 ba 00 00 00 00 00 fc ff df 41 c6 04 14 f8 48 01 d3 d1 e8 65 ff 0d 20 ad 9d 7e <48> c7 03 00 00 00 00 83 e0 01 c7 43 08 00 00 00 00 48 83 c4 68 
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4506 Comm: syz-executor146 Not tainted 4.17.0-rc5+ #57
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:lock_release+0x4fd/0xa10 kernel/locking/lockdep.c:3929
RSP: 0018:ffff8801d89678b0 EFLAGS: 00000086
RAX: dffffc0000000000 RBX: ffffed003b12cf1b RCX: 1ffff1003b100d9d
RDX: 1ffffffff11a30e5 RSI: 0000000000000004 RDI: 0000000000000086
RBP: ffff8801d89679e0 R08: 1ffff1003b12cf1f R09: 0000000000000003
R10: 0000000000000003 R11: 0000000000000003 R12: ffff8801d88064c0
R13: ffffffff88c12648 R14: ffff8801d88064c0 R15: ffff8801d89678f8
FS:  0000000001da9880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001dba918 CR3: 00000001d8f15000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 seqcount_lockdep_reader_access include/linux/seqlock.h:82 [inline]
 read_seqcount_begin include/linux/seqlock.h:164 [inline]
 read_seqbegin include/linux/seqlock.h:433 [inline]
 read_seqbegin_or_lock include/linux/seqlock.h:529 [inline]
 d_walk+0x1d5/0xc80 fs/dcache.c:1248
 shrink_dcache_parent+0x179/0x230 fs/dcache.c:1486
 vfs_rmdir+0x202/0x470 fs/namei.c:3850
 do_rmdir+0x523/0x610 fs/namei.c:3911
 __do_sys_rmdir fs/namei.c:3929 [inline]
 __se_sys_rmdir fs/namei.c:3927 [inline]
 __x64_sys_rmdir+0x36/0x40 fs/namei.c:3927
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446967
RSP: 002b:00007fffb1134178 EFLAGS: 00000207 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 0000000000446967
RDX: 0000000000000000 RSI: 00000000006db898 RDI: 00007fffb1135260
RBP: 00007fffb1135260 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000005 R11: 0000000000000207 R12: 0000000001daa8a0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Code: 57 9d 0f 1f 44 00 00 48 b8 00 00 00 00 00 fc ff df 48 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 c7 43 10 00 00 00 00 <c7> 43 18 00 00 00 00 48 81 c4 08 01 00 00 5b 41 5c 41 5d 41 5e

Crashes (163):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/05/19 05:03 upstream 2c71d338bef2 849705db .config console log report syz C ci-upstream-kasan-gce-root
2018/05/19 03:50 bpf-next 82f9e2d5dba6 849705db .config console log report syz C ci-upstream-bpf-next-kasan-gce
2018/05/19 02:27 bpf-next 82f9e2d5dba6 849705db .config console log report syz C ci-upstream-bpf-next-kasan-gce
2018/06/02 04:27 upstream 0512e0134582 2f93b54f .config console log report ci-upstream-kasan-gce-root
2018/05/30 09:01 upstream 0044cdeb7313 2f93b54f .config console log report ci-upstream-kasan-gce-root
2018/05/30 07:36 upstream 0044cdeb7313 2f93b54f .config console log report ci-upstream-kasan-gce-root
2018/05/29 11:39 upstream 786b71f5b754 f48c20b8 .config console log report ci-upstream-kasan-gce-root
2018/05/20 21:18 upstream 203ec2fed17a f48c20b8 .config console log report ci-upstream-kasan-gce-root
2018/05/18 20:51 upstream 2c71d338bef2 849705db .config console log report ci-upstream-kasan-gce-root
2018/05/18 20:33 upstream 2c71d338bef2 849705db .config console log report ci-upstream-kasan-gce-root
2018/06/11 11:40 bpf-next 75d4e704fa8d ae8bdb50 .config console log report ci-upstream-bpf-next-kasan-gce
2018/06/09 22:03 bpf-next 75d4e704fa8d 866118af .config console log report ci-upstream-bpf-next-kasan-gce
2018/06/07 05:45 bpf-next 75d4e704fa8d e0e534c6 .config console log report ci-upstream-bpf-next-kasan-gce
2018/06/04 17:49 bpf-next bd3a08aaa9a3 6cbe7c26 .config console log report ci-upstream-bpf-next-kasan-gce
2018/06/04 07:47 bpf-next bd3a08aaa9a3 2f93b54f .config console log report ci-upstream-bpf-next-kasan-gce
2018/06/03 00:37 bpf-next 25c1013e0464 2f93b54f .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/31 19:07 bpf-next bcece5dc40b9 2f93b54f .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/31 17:42 bpf-next bcece5dc40b9 2f93b54f .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/28 06:01 bpf-next a493f5f9d8c2 f48c20b8 .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/26 17:10 bpf-next 9c5904904b88 f48c20b8 .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/25 12:10 bpf-next 10f678683e40 f48c20b8 .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/24 14:51 bpf-next 31ad39239f08 f48c20b8 .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/23 23:05 bpf-next ff4fb475cea8 f48c20b8 .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/23 09:17 bpf-next 3fb48d881dbe f48c20b8 .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/20 03:52 bpf-next d849f9f9768c f48c20b8 .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/19 11:47 bpf-next d849f9f9768c 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 21:14 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 21:11 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 21:09 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 21:07 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 21:06 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 21:04 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:59 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:46 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:43 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:40 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:37 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:24 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:15 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:14 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:09 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:09 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:06 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 20:02 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 19:59 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/05/18 19:55 bpf-next 82f9e2d5dba6 849705db .config console log report ci-upstream-bpf-next-kasan-gce
2018/04/26 22:58 bpf-next 9b984a20ca84 73417389 .config console log report ci-upstream-bpf-next-kasan-gce
* Struck through repros no longer work on HEAD.