general protection fault in fsnotify

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 34d4ddd3 Merge tag 'linux-kselftest-5.9-rc5' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14015853900000
kernel config: https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9
dashboard link: https://syzkaller.appspot.com/bug?extid=e6ec73733035d4ded001
compiler: gcc (GCC) 10.1.0-syz 20200507
CC: [amir...@gmail.com ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e6ec73...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc00000000d2: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000690-0x0000000000000697]
CPU: 1 PID: 1182 Comm: khugepaged Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fsnotify+0x196/0xf80 fs/notify/fsnotify.c:458
Code: 48 c1 ea 03 80 3c 02 00 0f 85 c5 0d 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 75 28 4d 8d ae 90 06 00 00 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 4c 0d 00 00 49 83 be 90 06 00 00 00 0f 84 b1 0a
RSP: 0018:ffffc90004fa7180 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81d14e5d
RDX: 00000000000000d2 RSI: ffffffff81d14e6b RDI: ffff88800080d168
RBP: ffff88800080d140 R08: 0000000000000000 R09: ffff88800080d140
R10: 0000000000000000 R11: ffffffff8c628d10 R12: 0000000000000000
R13: 0000000000000690 R14: 0000000000000000 R15: 0000000000000002
FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000744138 CR3: 0000000093d13000 CR4: 00000000001526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
fsnotify_inode include/linux/fsnotify.h:47 [inline]
fsnotify_inoderemove include/linux/fsnotify.h:178 [inline]
dentry_unlink_inode+0x32d/0x3d0 fs/dcache.c:370
__dentry_kill+0x3c0/0x640 fs/dcache.c:579
shrink_dentry_list+0x144/0x480 fs/dcache.c:1141
prune_dcache_sb+0xe7/0x140 fs/dcache.c:1222
super_cache_scan+0x336/0x590 fs/super.c:105
do_shrink_slab+0x3c6/0xab0 mm/vmscan.c:513
shrink_slab+0x16f/0x5d0 mm/vmscan.c:674
shrink_node_memcgs mm/vmscan.c:2653 [inline]
shrink_node+0x8a2/0x1d20 mm/vmscan.c:2768
shrink_zones mm/vmscan.c:2971 [inline]
do_try_to_free_pages+0x38b/0x1420 mm/vmscan.c:3026
try_to_free_pages+0x29e/0x7d0 mm/vmscan.c:3265
__perform_reclaim mm/page_alloc.c:4260 [inline]
__alloc_pages_direct_reclaim mm/page_alloc.c:4281 [inline]
__alloc_pages_slowpath.constprop.0+0x995/0x2830 mm/page_alloc.c:4685
__alloc_pages_nodemask+0x62c/0x790 mm/page_alloc.c:4901
__alloc_pages include/linux/gfp.h:509 [inline]
__alloc_pages_node include/linux/gfp.h:522 [inline]
khugepaged_alloc_page+0xa0/0x170 mm/khugepaged.c:867
collapse_huge_page mm/khugepaged.c:1059 [inline]
khugepaged_scan_pmd mm/khugepaged.c:1349 [inline]
khugepaged_scan_mm_slot mm/khugepaged.c:2108 [inline]
khugepaged_do_scan mm/khugepaged.c:2191 [inline]
khugepaged+0x319e/0x5a90 mm/khugepaged.c:2236
kthread+0x3b5/0x4a0 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Modules linked in:
---[ end trace a7b66d76157ae260 ]---
RIP: 0010:fsnotify+0x196/0xf80 fs/notify/fsnotify.c:458
Code: 48 c1 ea 03 80 3c 02 00 0f 85 c5 0d 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 75 28 4d 8d ae 90 06 00 00 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 4c 0d 00 00 49 83 be 90 06 00 00 00 0f 84 b1 0a
RSP: 0018:ffffc90004fa7180 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81d14e5d
RDX: 00000000000000d2 RSI: ffffffff81d14e6b RDI: ffff88800080d168
RBP: ffff88800080d140 R08: 0000000000000000 R09: ffff88800080d140
R10: 0000000000000000 R11: ffffffff8c628d10 R12: 0000000000000000
R13: 0000000000000690 R14: 0000000000000000 R15: 0000000000000002
FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000744138 CR3: 00000000a80f7000 CR4: 00000000001526e0
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.