INFO: rcu detected stall in bitmap_parselist

[syzbot <syzbot+6887cbb011c8054e8a3d@syzkaller.appspotmail.com>]

Hello,

syzbot hit the following crash on upstream commit
3eb2ce825ea1ad89d20f7a3b5780df850e4be274 (Sun Mar 25 22:44:30 2018 +0000)
Linux 4.16-rc7
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=6887cbb011c8054e8a3d

So far this crash happened 3 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=5674881425342464
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-8440362230543204781
compiler: gcc (GCC) 7.1.1 20170620

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6887cbb011c8054e8a3d@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

INFO: rcu_sched self-detected stall on CPU
	1-....: (124999 ticks this GP) idle=0da/1/4611686018427387906  
softirq=49340/49340 fqs=31180
	 (t=125000 jiffies g=24134 c=24133 q=654)
NMI backtrace for cpu 1
CPU: 1 PID: 14671 Comm: syz-executor3 Not tainted 4.16.0-rc7+ #368
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  <IRQ>
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x24d lib/dump_stack.c:53
  nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
  nmi_trigger_cpumask_backtrace+0x123/0x180 lib/nmi_backtrace.c:62
  arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
  trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
  rcu_dump_cpu_stacks+0x186/0x1de kernel/rcu/tree.c:1375
  print_cpu_stall kernel/rcu/tree.c:1524 [inline]
  check_cpu_stall.isra.61+0xbb8/0x15b0 kernel/rcu/tree.c:1592
  __rcu_pending kernel/rcu/tree.c:3361 [inline]
  rcu_pending kernel/rcu/tree.c:3423 [inline]
  rcu_check_callbacks+0x238/0xd20 kernel/rcu/tree.c:2763
  update_process_times+0x30/0x60 kernel/time/timer.c:1636
  tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
  tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1194
  __run_hrtimer kernel/time/hrtimer.c:1349 [inline]
  __hrtimer_run_queues+0x39c/0xec0 kernel/time/hrtimer.c:1411
  hrtimer_interrupt+0x2a5/0x6f0 kernel/time/hrtimer.c:1469
  local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
  smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:857
  </IRQ>
RIP: 0010:__bitmap_parselist+0x2f0/0x4b0 lib/bitmap.c:612
RSP: 0018:ffff88019ef0f6d8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff12
RAX: 0000000000010000 RBX: 0000000000000001 RCX: ffffffff82af9d1d
RDX: 0000000000010000 RSI: ffffc900042fb000 RDI: ffff8801b5a023e0
RBP: ffff88019ef0f750 R08: ffffed0036b4047d R09: ffff8801b5a023e0
R10: 0000000000000001 R11: ffffed0036b4047c R12: 0000000000000008
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
  bitmap_parselist+0x3a/0x50 lib/bitmap.c:628
  cpulist_parse include/linux/cpumask.h:639 [inline]
  update_cpumask kernel/cgroup/cpuset.c:974 [inline]
  cpuset_write_resmask+0x1694/0x2850 kernel/cgroup/cpuset.c:1724
  cgroup_file_write+0x2ae/0x710 kernel/cgroup/cgroup.c:3429
  kernfs_fop_write+0x2bc/0x440 fs/kernfs/file.c:316
  __vfs_write+0xef/0x970 fs/read_write.c:480
  vfs_write+0x189/0x510 fs/read_write.c:544
  SYSC_write fs/read_write.c:589 [inline]
  SyS_write+0xef/0x220 fs/read_write.c:581
  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x454879
RSP: 002b:00007f01ef5b4c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f01ef5b56d4 RCX: 0000000000454879
RDX: 0000000000000002 RSI: 0000000020000040 RDI: 0000000000000014
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000006a1 R14: 00000000006fbfb8 R15: 0000000000000000


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@googlegroups.com.

syzbot will keep track of this bug report.
If you forgot to add the Reported-by tag, once the fix for this bug is  
merged
into any tree, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug  
report.
Note: all commands must start from beginning of the line in the email body.