general protection fault in mark_buffer_dirty_inode

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 3f018f4a Add linux-next specific files for 20190418
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1026fb2d200000
kernel config: https://syzkaller.appspot.com/x/.config?x=faa7bdc352fc157e
dashboard link: https://syzkaller.appspot.com/bug?extid=08660460861a48d96539
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk]

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+086604...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 10745 Comm: syz-executor.0 Not tainted 5.1.0-rc5-next-20190418
#28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:perf_trace_lock_acquire+0x9d/0x580 include/trace/events/lock.h:13
Code: 04 f1 f1 04 f2 c7 40 08 00 f3 f3 f3 65 48 8b 04 25 28 00 00 00 48 89
45 d0 31 c0 48 8d 46 18 48 89 85 48 ff ff ff 48 c1 e8 03 <80> 3c 10 00 0f
85 6d 03 00 00 49 8b 7e 18 48 85 ff 0f 84 0f 03 00
RSP: 0018:ffff88805ae470a8 EFLAGS: 00010002
RAX: 0000000000000029 RBX: ffff88809bb8b8a8 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000130 RDI: ffffffff8898a6c0
RBP: ffff88805ae47190 R08: 0000000000000000 R09: 0000000000000001
R10: ffffed1015d05dcf R11: 0000000000000001 R12: ffffffff8898a6c0
R13: 0000000000000000 R14: 0000000000000130 R15: ffff88805ae47168
FS: 00007f07487b4700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555556bce978 CR3: 00000000955fa000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
trace_lock_acquire include/trace/events/lock.h:13 [inline]
lock_acquire+0x29c/0x3f0 kernel/locking/lockdep.c:4199
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
mark_buffer_dirty_inode+0x133/0x410 fs/buffer.c:556
fat16_ent_put+0xd2/0x110 fs/fat/fatent.c:182
fat_alloc_clusters+0x63e/0xf40 fs/fat/fatent.c:498
fat_add_cluster+0x6f/0x100 fs/fat/inode.c:101
__fat_get_block fs/fat/inode.c:148 [inline]
fat_get_block+0x344/0x970 fs/fat/inode.c:183
__block_write_begin_int+0x4e0/0x1920 fs/buffer.c:2004
__block_write_begin fs/buffer.c:2054 [inline]
block_write_begin+0x5f/0x1e0 fs/buffer.c:2113
cont_write_begin+0x4ef/0x8d0 fs/buffer.c:2466
fat_write_begin+0x8d/0x120 fs/fat/inode.c:229
generic_perform_write+0x231/0x530 mm/filemap.c:3266
__generic_file_write_iter+0x25e/0x630 mm/filemap.c:3395
generic_file_write_iter+0x360/0x610 mm/filemap.c:3427
call_write_iter include/linux/fs.h:1866 [inline]
new_sync_write+0x4c7/0x760 fs/read_write.c:474
__vfs_write+0xe4/0x110 fs/read_write.c:487
vfs_write+0x20c/0x580 fs/read_write.c:549
ksys_write+0x14f/0x2d0 fs/read_write.c:599
__do_sys_write fs/read_write.c:611 [inline]
__se_sys_write fs/read_write.c:608 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:608
do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458c29
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f07487b3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458c29
RDX: 000000000000004a RSI: 00000000200005c0 RDI: 0000000000000006
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f07487b46d4
R13: 00000000004c8611 R14: 00000000004ded50 R15: 00000000ffffffff
Modules linked in:
---[ end trace 529dc8cf7c4a532a ]---
RIP: 0010:perf_trace_lock_acquire+0x9d/0x580 include/trace/events/lock.h:13
Code: 04 f1 f1 04 f2 c7 40 08 00 f3 f3 f3 65 48 8b 04 25 28 00 00 00 48 89
45 d0 31 c0 48 8d 46 18 48 89 85 48 ff ff ff 48 c1 e8 03 <80> 3c 10 00 0f
85 6d 03 00 00 49 8b 7e 18 48 85 ff 0f 84 0f 03 00
RSP: 0018:ffff88805ae470a8 EFLAGS: 00010002
RAX: 0000000000000029 RBX: ffff88809bb8b8a8 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000130 RDI: ffffffff8898a6c0
RBP: ffff88805ae47190 R08: 0000000000000000 R09: 0000000000000001
R10: ffffed1015d05dcf R11: 0000000000000001 R12: ffffffff8898a6c0
R13: 0000000000000000 R14: 0000000000000130 R15: ffff88805ae47168
FS: 00007f07487b4700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555556bce978 CR3: 00000000955fa000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.