Crashes in next-20160915 (BUG at fs/notify/notification.c:66!)

[Guenter Roeck]

Hi,

I see various architectures crashing in -next with the following error.

------------[ cut here ]------------
kernel BUG at fs/notify/notification.c:66!
invalid opcode: 0000 [#1] PREEMPT
Modules linked in:
CPU: 0 PID: 110 Comm: udevd Not tainted 4.8.0-rc6-next-20160915-yocto-standard #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.1-0-gb3ef39f-prebuilt.qemu-project.org 04/01/2014
task: ffff88000dd58000 task.stack: ffffc90000250000
RIP: 0010:[<ffffffff811bb399>]  [<ffffffff811bb399>] fsnotify_notify_queue_is_empty+0x9/0x10
RSP: 0018:ffffc90000253e68  EFLAGS: 00000296
RAX: ffff88000dd58000 RBX: ffff88000dc9a9c0 RCX: 0000000000011ff0
RDX: ffffffff811bd52a RSI: ffff88000e3c1258 RDI: ffff88000dc9a9c0
RBP: ffffc90000253e68 R08: ffff88000ffd37e0 R09: ffff88000dcdd600
R10: ffff88000dcdd600 R11: 0000000000000000 R12: 0000000000000001
R13: ffff88000dd28c00 R14: ffff88000dc0a380 R15: ffff88000dc0a398
FS:  00007ff5bea85740(0000) GS:ffffffff81c31000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff5bea79000 CR3: 000000000dd63000 CR4: 00000000000406f0
Stack:
 ffffc90000253e88 ffffffff811bd532 0000000000000000 ffff88000dd28c00
 ffffc90000253f48 ffffffff811bfeba ffffffff00000006 0000000000000000
 ffff88000dcdd600 ffff88000dcdd600 0000001900253f58 0000040000080002
Call Trace:
 [<ffffffff811bd532>] inotify_poll+0x42/0x70
 [<ffffffff811bfeba>] SyS_epoll_ctl+0x84a/0xf60
 [<ffffffff811be4a0>] ? ep_send_events_proc+0x180/0x180
 [<ffffffff8176be98>] entry_SYSCALL_64_fastpath+0x13/0x8f
Code: 90 90 0f 1f 44 00 00 55 b8 01 00 00 00 48 89 e5 0f c1 05 bb e4 d4 00 83 c0 01 5d c3 66 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 e5 <0f> 0b 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 e5 48 83 ec 10 48
RIP  [<ffffffff811bb399>] fsnotify_notify_queue_is_empty+0x9/0x10
 RSP <ffffc90000253e68>
---[ end trace 7dc4a27003f0b575 ]---

I didn't bisect, but I would guess the culprit is one of the new patches in the
affected file.

22e9cf146d3b fanotify: fix possible false warning when freeing events
ced89591817c fsnotify: convert notification_mutex to a spinlock
f82fa3d0e7f5 fsnotify: drop notification_mutex before destroying event
782fbc7e8685 fanotify: fix list corruption in fanotify_get_response()
56cf1c8a1b35 fsnotify: add a way to stop queueing events on group shutdown

Guenter