WARNING in schedule_bh

Wed Jan 15 16:15:12 UTC 2020

Hello,

syzbot found the following crash on:

HEAD commit:    95e20af9 Merge tag 'nfs-for-5.5-2' of git://git.linux-nfs...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17648c21e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d9290aeb7e6cf1c4
dashboard link: https://syzkaller.appspot.com/bug?extid=bfc0855888f853dca7ad
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bfc0855888f853dca7ad at syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 3 PID: 12339 at drivers/block/floppy.c:985  
schedule_bh+0x67/0x70 drivers/block/floppy.c:985
Kernel panic - not syncing: panic_on_warn set ...
CPU: 3 PID: 12339 Comm: syz-executor.1 Not tainted 5.5.0-rc6-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS  
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x197/0x210 lib/dump_stack.c:118
  panic+0x2e3/0x75c kernel/panic.c:221
  __warn.cold+0x2f/0x3e kernel/panic.c:582
  report_bug+0x289/0x300 lib/bug.c:195
  fixup_bug arch/x86/kernel/traps.c:174 [inline]
  fixup_bug arch/x86/kernel/traps.c:169 [inline]
  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:schedule_bh+0x67/0x70 drivers/block/floppy.c:985
Code: fd 48 8b 35 8b 82 ab 07 48 c7 c2 c0 80 00 8a bf 40 00 00 00 4c 89 25  
98 7d ab 07 e8 93 51 e3 fc 5b 41 5c 5d c3 e8 09 4a 0b fd <0f> 0b eb ce 0f  
1f 44 00 00 55 48 89 e5 e8 f7 49 0b fd 48 c7 c7 10
RSP: 0018:ffffc900075774b0 EFLAGS: 00010212
RAX: 0000000000040000 RBX: 0000000000000001 RCX: ffffc900039f0000
RDX: 00000000000086ed RSI: ffffffff8469ab77 RDI: 0000000000000007
RBP: ffffc900075774c0 R08: ffff888028b50d40 R09: fffffbfff1401019
R10: fffffbfff1401018 R11: ffffffff8a0080c7 R12: ffffffff846a94a0
R13: ffffffff846a94a0 R14: 0000000000000001 R15: 0000000000000001
  wait_til_done+0x88/0x370 drivers/block/floppy.c:1977
  poll_drive+0xd5/0xf0 drivers/block/floppy.c:2939
  floppy_check_events+0x39f/0x440 drivers/block/floppy.c:4107
  disk_check_events+0x13b/0x5c0 block/genhd.c:1859
  disk_clear_events+0x143/0x318 block/genhd.c:1819
  check_disk_change+0x79/0x140 fs/block_dev.c:1488
  floppy_open+0x6ba/0xae0 drivers/block/floppy.c:4067
  __blkdev_get+0x34f/0x1650 fs/block_dev.c:1604
  blkdev_get+0x47/0x2c0 fs/block_dev.c:1736
  blkdev_open+0x205/0x290 fs/block_dev.c:1875
  do_dentry_open+0x4e6/0x1380 fs/open.c:797
  vfs_open+0xa0/0xd0 fs/open.c:914
  do_last fs/namei.c:3420 [inline]
  path_openat+0x10df/0x4500 fs/namei.c:3537
  do_filp_open+0x1a1/0x280 fs/namei.c:3567
  do_sys_open+0x3fe/0x5d0 fs/open.c:1097
  __do_compat_sys_open fs/open.c:1134 [inline]
  __se_compat_sys_open fs/open.c:1132 [inline]
  __ia32_compat_sys_open+0x79/0xb0 fs/open.c:1132
  do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
  do_fast_syscall_32+0x27b/0xe16 arch/x86/entry/common.c:408
  entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fa9a39
Code: 00 00 00 89 d3 5b 5e 5f 5d c3 b8 80 96 98 00 eb c4 8b 04 24 c3 8b 1c  
24 c3 8b 34 24 c3 8b 3c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90  
90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5da4c04 EFLAGS: 00000293 ORIG_RAX: 0000000000000005
RAX: ffffffffffffffda RBX: 00000000f5da4cc0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000066666667 RDI: 00000000f5da4cc0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled

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