syzbot


INFO: rcu detected stall in _do_fork

Status: upstream: reported syz repro on 2021/12/30 08:01
Reported-by: syzbot+5015af38273cd497c692@syzkaller.appspotmail.com
First crash: 846d, last: 837d
Fix bisection: failed (error log, bisect log)
  
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 INFO: rcu detected stall in _do_fork 3 1633d 1645d 0/1 auto-closed as invalid on 2020/03/03 21:19
linux-4.19 BUG: soft lockup in _do_fork 1 1106d 1106d 0/1 auto-closed as invalid on 2021/08/12 22:53
linux-4.14 BUG: soft lockup in _do_fork 1 717d 717d 0/1 auto-obsoleted due to no activity on 2022/09/05 14:27

Sample crash report:
watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [syz-executor.0:20832]
Modules linked in:
irq event stamp: 2726218
hardirqs last  enabled at (2726217): [<ffffffff81003ce4>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (2726218): [<ffffffff81003d00>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last  enabled at (94154): [<ffffffff88400678>] __do_softirq+0x678/0x980 kernel/softirq.c:318
softirqs last disabled at (88817): [<ffffffff813927d5>] invoke_softirq kernel/softirq.c:372 [inline]
softirqs last disabled at (88817): [<ffffffff813927d5>] irq_exit+0x215/0x260 kernel/softirq.c:412
CPU: 0 PID: 20832 Comm: syz-executor.0 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:435 [inline]
RIP: 0010:__pv_queued_spin_lock_slowpath+0x3a6/0xae0 kernel/locking/qspinlock.c:474
Code: eb c6 45 01 01 41 bc 00 80 00 00 48 c1 e9 03 83 e3 07 41 be 01 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8d 2c 01 eb 0c f3 90 <41> 83 ec 01 0f 84 38 04 00 00 41 0f b6 45 00 38 d8 7f 08 84 c0 0f
RSP: 0018:ffff88822c6778c0 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000003 RBX: 0000000000000000 RCX: 1ffffffff140787c
RDX: 0000000000000001 RSI: ffffffff8167a995 RDI: 0000000000000286
RBP: ffffffff8a03c3e0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000fe7
R13: fffffbfff140787c R14: 0000000000000001 R15: ffff8880ba02be00
FS:  00007fc335a66700(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc336400000 CR3: 000000022c75f000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:679 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:53 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:88 [inline]
 do_raw_spin_lock+0x189/0x220 kernel/locking/spinlock_debug.c:113
 spin_lock include/linux/spinlock.h:329 [inline]
 sget_userns+0xcc/0xcd0 fs/super.c:501
 mount_ns+0x8d/0x1d0 fs/super.c:1068
 mount_fs+0xa3/0x310 fs/super.c:1261
 vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 kern_mount_data+0x55/0xd0 fs/namespace.c:3278
 pid_ns_prepare_proc+0x1a/0x90 fs/proc/root.c:214
 alloc_pid+0x721/0x8f0 kernel/pid.c:208
 copy_process.part.0+0x3bc0/0x8260 kernel/fork.c:1927
 copy_process kernel/fork.c:1710 [inline]
 _do_fork+0x22f/0xf30 kernel/fork.c:2219
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fc3362f0e99
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc335a66168 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fc336403f60 RCX: 00007fc3362f0e99
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 0000000020002100
RBP: 00007fc33634aff1 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffea510a86f R14: 00007fc335a66300 R15: 0000000000022000
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 20830 Comm: syz-executor.5 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:apic_timer_interrupt+0x5/0x20 arch/x86/entry/entry_64.S:894
Code: 28 e0 f8 48 89 e7 e8 0a 68 e0 f8 e8 8f 28 e0 f8 e9 85 f5 ff ff c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 68 13 ff ff ff <e8> 46 f4 ff ff e8 01 2a 00 00 e9 2b f5 ff ff 66 66 2e 0f 1f 84 00
RSP: 0018:ffff8880ba107690 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: 1ffff11017420ed9 RCX: 0000000000000000
RDX: 1ffff11017420f12 RSI: ffff8880ba107f80 RDI: ffff8880ba107898
RBP: ffff8880ba107f80 R08: 0000000000000001 R09: 0000000000000001
R10: ffff8880ba1078e7 R11: 0000000000074071 R12: ffff8880ba107888
R13: ffff8880ba1078c8 R14: ffff8880ba100000 R15: ffffffff8c11cfdc
FS:  00007fae1b5a2700(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe882b6b000 CR3: 00000002316a4000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:42 [inline]
RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:321 [inline]
RIP: 0010:deref_stack_reg+0xb7/0x1d0 arch/x86/kernel/unwind_orc.c:331
Code: 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 00 01 00 00 49 8d 7c 24 10 4d 8b 74 24 08 48 b8 00 00 00 00 00 fc ff df <48> 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c7 00 00 00 49 39 ee 49 8b
RSP: 0018:ffff8880ba1076c0 EFLAGS: 00000246
 unwind_next_frame+0xf83/0x1400 arch/x86/kernel/unwind_orc.c:555
 __save_stack_trace+0x9f/0x190 arch/x86/kernel/stacktrace.c:44
 save_stack mm/kasan/kasan.c:448 [inline]
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:553
 slab_post_alloc_hook mm/slab.h:445 [inline]
 slab_alloc_node mm/slab.c:3340 [inline]
 kmem_cache_alloc_node+0x133/0x3b0 mm/slab.c:3647
 __alloc_skb+0x71/0x560 net/core/skbuff.c:193
 skb_copy+0x139/0x2f0 net/core/skbuff.c:1358
 mac80211_hwsim_tx_frame_no_nl.isra.0+0xb8a/0x1330 drivers/net/wireless/mac80211_hwsim.c:1353
 mac80211_hwsim_tx_frame+0x12b/0x210 drivers/net/wireless/mac80211_hwsim.c:1556
 mac80211_hwsim_beacon_tx+0x3f8/0x680 drivers/net/wireless/mac80211_hwsim.c:1595
 __iterate_interfaces+0x2e1/0x4a0 net/mac80211/util.c:614
 ieee80211_iterate_active_interfaces_atomic+0x8d/0x170 net/mac80211/util.c:650
 mac80211_hwsim_beacon+0xc9/0x190 drivers/net/wireless/mac80211_hwsim.c:1615
 __tasklet_hrtimer_trampoline+0x29/0xa0 kernel/softirq.c:601
 tasklet_action_common.constprop.0+0x265/0x360 kernel/softirq.c:522
 __do_softirq+0x265/0x980 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:372 [inline]
 irq_exit+0x215/0x260 kernel/softirq.c:412
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x136/0x550 arch/x86/kernel/apic/apic.c:1098
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894
 </IRQ>
RIP: 0010:ns_test_super+0x2b/0x50 fs/super.c:1047
Code: 48 89 f5 53 48 89 fb e8 a3 4e bf ff 48 8d bb 80 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 0f <31> c0 48 39 ab 80 06 00 00 5b 5d 0f 94 c0 c3 e8 61 2b f5 ff eb ea
RSP: 0018:ffff88822c6879b0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffff8880aa14c8c0 RCX: ffffffff81a3594b
RDX: 1ffff110154299e8 RSI: ffffffff81a336cd RDI: ffff8880aa14cf40
RBP: ffff88809d81ba18 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000005 R11: 00000000e79d86ea R12: ffff8880aa14c8c0
R13: ffffffff8a066ca8 R14: ffff888072cf6ed0 R15: dffffc0000000000
 sget_userns+0x300/0xcd0 fs/super.c:504
 mount_ns+0x8d/0x1d0 fs/super.c:1068
 mount_fs+0xa3/0x310 fs/super.c:1261
 vfs_kern_mount.part.0+0x68/0x470 fs/namespace.c:961
 vfs_kern_mount fs/namespace.c:951 [inline]
 kern_mount_data+0x55/0xd0 fs/namespace.c:3278
 pid_ns_prepare_proc+0x1a/0x90 fs/proc/root.c:214
 alloc_pid+0x721/0x8f0 kernel/pid.c:208
 copy_process.part.0+0x3bc0/0x8260 kernel/fork.c:1927
 copy_process kernel/fork.c:1710 [inline]
 _do_fork+0x22f/0xf30 kernel/fork.c:2219
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fae1be2ce99
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fae1b5a2168 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fae1bf3ff60 RCX: 00007fae1be2ce99
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 0000000020002100
RBP: 00007fae1be86ff1 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff85e9057f R14: 00007fae1b5a2300 R15: 0000000000022000
----------------
Code disassembly (best guess):
   0:	eb c6                	jmp    0xffffffc8
   2:	45 01 01             	add    %r8d,(%r9)
   5:	41 bc 00 80 00 00    	mov    $0x8000,%r12d
   b:	48 c1 e9 03          	shr    $0x3,%rcx
   f:	83 e3 07             	and    $0x7,%ebx
  12:	41 be 01 00 00 00    	mov    $0x1,%r14d
  18:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1f:	fc ff df
  22:	4c 8d 2c 01          	lea    (%rcx,%rax,1),%r13
  26:	eb 0c                	jmp    0x34
  28:	f3 90                	pause
* 2a:	41 83 ec 01          	sub    $0x1,%r12d <-- trapping instruction
  2e:	0f 84 38 04 00 00    	je     0x46c
  34:	41 0f b6 45 00       	movzbl 0x0(%r13),%eax
  39:	38 d8                	cmp    %bl,%al
  3b:	7f 08                	jg     0x45
  3d:	84 c0                	test   %al,%al
  3f:	0f                   	.byte 0xf

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/01/02 16:59 linux-4.19.y 3f8a27f9e27b e1768e9c .config console log report syz ci2-linux-4-19 BUG: soft lockup in _do_fork
2022/01/08 15:30 linux-4.19.y 3f8a27f9e27b 2ca0d385 .config console log report info ci2-linux-4-19 INFO: rcu detected stall in _do_fork
2021/12/30 08:00 linux-4.19.y 3f8a27f9e27b 6cc879d4 .config console log report info ci2-linux-4-19 INFO: rcu detected stall in _do_fork
* Struck through repros no longer work on HEAD.