WARNING in __blk_mq_delay_run_hw_queue

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: b145b0eb Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=146c860d600000
kernel config: https://syzkaller.appspot.com/x/.config?x=1ec3be9936e004f6
dashboard link: https://syzkaller.appspot.com/bug?extid=d44e1b26ce5c3e77458d
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=165fcefb600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=162d03db600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d44e1b...@syzkaller.appspotmail.com

blk_update_request: I/O error, dev nbd0, sector 4 op 0x0:(READ) flags 0x0
phys_seg 2 prio class 0
Buffer I/O error on dev nbd0, logical block 2, async page read
Buffer I/O error on dev nbd0, logical block 3, async page read
------------[ cut here ]------------
WARNING: CPU: 0 PID: 2496 at include/linux/cpumask.h:137 cpu_max_bits_warn
include/linux/cpumask.h:137 [inline]
WARNING: CPU: 0 PID: 2496 at include/linux/cpumask.h:137 cpumask_check
include/linux/cpumask.h:144 [inline]
WARNING: CPU: 0 PID: 2496 at include/linux/cpumask.h:137 cpumask_check
include/linux/cpumask.h:142 [inline]
WARNING: CPU: 0 PID: 2496 at include/linux/cpumask.h:137 cpumask_test_cpu
include/linux/cpumask.h:360 [inline]
WARNING: CPU: 0 PID: 2496 at include/linux/cpumask.h:137
blk_mq_hctx_next_cpu block/blk-mq.c:1443 [inline]
WARNING: CPU: 0 PID: 2496 at include/linux/cpumask.h:137
__blk_mq_delay_run_hw_queue+0x498/0x600 block/blk-mq.c:1479
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 2496 Comm: kworker/0:1H Not tainted 5.4.0-rc1+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: kblockd blk_mq_requeue_work
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
panic+0x2dc/0x755 kernel/panic.c:220
__warn.cold+0x2f/0x3c kernel/panic.c:581
report_bug+0x289/0x300 lib/bug.c:195
fixup_bug arch/x86/kernel/traps.c:179 [inline]
fixup_bug arch/x86/kernel/traps.c:174 [inline]
do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:cpu_max_bits_warn include/linux/cpumask.h:137 [inline]
RIP: 0010:cpumask_check include/linux/cpumask.h:144 [inline]
RIP: 0010:cpumask_check include/linux/cpumask.h:142 [inline]
RIP: 0010:cpumask_test_cpu include/linux/cpumask.h:360 [inline]
RIP: 0010:blk_mq_hctx_next_cpu block/blk-mq.c:1443 [inline]
RIP: 0010:__blk_mq_delay_run_hw_queue+0x498/0x600 block/blk-mq.c:1479
Code: 01 00 00 41 c7 84 24 24 01 00 00 01 00 00 00 41 bd 40 00 00 00 e9 ab
fe ff ff 41 bd 40 00 00 00 e9 a0 fe ff ff e8 48 68 41 fe <0f> 0b e9 50 fd
ff ff e8 3c 68 41 fe 48 c7 c2 40 b9 c5 89 4c 89 fe
RSP: 0018:ffff8880a3287b18 EFLAGS: 00010293
RAX: ffff8880a32720c0 RBX: 0000000000000040 RCX: ffffffff8331a7e6
RDX: 0000000000000000 RSI: ffffffff8331aa98 RDI: 0000000000000005
RBP: ffff8880a3287b58 R08: ffff8880a32720c0 R09: ffffed101141a05a
R10: ffffed101141a059 R11: ffff88808a0d02cf R12: ffff88808a0d0280
R13: 0000000000000040 R14: ffff88808a0d03a4 R15: 0000000000000000
blk_mq_run_hw_queue+0x19d/0x350 block/blk-mq.c:1508
blk_mq_run_hw_queues+0x112/0x1a0 block/blk-mq.c:1525
blk_mq_requeue_work+0x502/0x780 block/blk-mq.c:775
process_one_work+0x9af/0x1740 kernel/workqueue.c:2269
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

syzbot has bisected this bug to:

commit ed76e329d74a4b15ac0f5fd3adbd52ec0178a134
Author: Jens Axboe <ax...@kernel.dk>
Date: Mon Oct 29 19:06:14 2018 +0000

blk-mq: abstract out queue map

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1558f6fb600000
start commit: b145b0eb Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=1758f6fb600000
console output: https://syzkaller.appspot.com/x/log.txt?x=1358f6fb600000

kernel config: https://syzkaller.appspot.com/x/.config?x=1ec3be9936e004f6
dashboard link: https://syzkaller.appspot.com/bug?extid=d44e1b26ce5c3e77458d

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=165fcefb600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=162d03db600000

Reported-by: syzbot+d44e1b...@syzkaller.appspotmail.com
Fixes: ed76e329d74a ("blk-mq: abstract out queue map")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection