BUG: unable to handle kernel NULL pointer dereference in kfree (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 483d835c8189 Add linux-next specific files for 20180713
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1332f3b2400000
kernel config: https://syzkaller.appspot.com/x/.config?x=60e5ac2478928314
dashboard link: https://syzkaller.appspot.com/bug?extid=74fe52114b3d4671fa2a
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: [ak...@linux-foundation.org arya...@virtuozzo.com
jba...@fb.com ktk...@virtuozzo.com linux-...@vger.kernel.org
linu...@kvack.org mho...@suse.com penguin...@I-love.SAKURA.ne.jp
s...@canb.auug.org.au shak...@google.com vdavyd...@gmail.com
wi...@infradead.org ying....@intel.com]

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+74fe52...@syzkaller.appspotmail.com

BUG: unable to handle kernel NULL pointer dereference at 0000000000000074
PGD 16290e067 P4D 16290e067 PUD 1c9e99067 PMD 0
Oops: 0000 [#1] SMP KASAN
CPU: 1 PID: 8870 Comm: syz-executor2 Tainted: G W
4.18.0-rc4-next-20180713+ #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:virt_to_cache mm/slab.c:400 [inline]
RIP: 0010:kfree+0xb2/0x260 mm/slab.c:3809
Code: 48 89 df 48 b8 00 00 00 00 00 ea ff ff 48 c1 ea 0c 48 c1 e2 06 48 01
c2 48 8b 42 08 a8 01 48 8d 48 ff 48 0f 45 d1 4c 8b 6a 18 <49> 63 75 74 e8
e5 c0 a3 ff 49 63 75 74 48 89 df e8 d9 8f a9 01 4c
RSP: 0018:ffff8801963feeb8 EFLAGS: 00010046
RAX: ffffea0000054008 RBX: ffffffff81500cc9 RCX: ffffea0000054007
RDX: ffffea0000054000 RSI: ffffffff81a635f1 RDI: ffffffff81500cc9
RBP: ffff8801963feed8 R08: ffff880191a04300 R09: ffffed003ae212a0
R10: ffffed003ae212a0 R11: ffff8801d7109507 R12: 0000000000000282
R13: 0000000000000000 R14: ffff880195d40ed8 R15: ffffffff81500cc9
FS: 00007feffa02a700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000074 CR3: 0000000195cc6000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kfree_const+0x59/0x70 mm/util.c:38
kobject_cleanup lib/kobject.c:649 [inline]
kobject_release lib/kobject.c:672 [inline]
kref_put include/linux/kref.h:70 [inline]
kobject_put+0x1af/0x280 lib/kobject.c:689
shrink_slab_memcg mm/vmscan.c:598 [inline]
shrink_slab+0x861/0xa60 mm/vmscan.c:671
shrink_node+0x429/0x16a0 mm/vmscan.c:2735
shrink_zones mm/vmscan.c:2964 [inline]
do_try_to_free_pages+0x3e7/0x1290 mm/vmscan.c:3026
try_to_free_mem_cgroup_pages+0x49d/0xc90 mm/vmscan.c:3324
memory_high_write+0x283/0x310 mm/memcontrol.c:5611
cgroup_file_write+0x31f/0x840 kernel/cgroup/cgroup.c:3502
kernfs_fop_write+0x2ba/0x480 fs/kernfs/file.c:316
__vfs_write+0x117/0x9d0 fs/read_write.c:485
vfs_write+0x1fc/0x560 fs/read_write.c:549
ksys_write+0x101/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455ab9
Code: 1d ba 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 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007feffa029c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007feffa02a6d4 RCX: 0000000000455ab9
RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000018
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004c2c77 R14: 00000000004d4c80 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
(ftrace buffer empty)
CR2: 0000000000000074
---[ end trace 4578d5d357e1b158 ]---
RIP: 0010:virt_to_cache mm/slab.c:400 [inline]
RIP: 0010:kfree+0xb2/0x260 mm/slab.c:3809
Code: 48 89 df 48 b8 00 00 00 00 00 ea ff ff 48 c1 ea 0c 48 c1 e2 06 48 01
c2 48 8b 42 08 a8 01 48 8d 48 ff 48 0f 45 d1 4c 8b 6a 18 <49> 63 75 74 e8
e5 c0 a3 ff 49 63 75 74 48 89 df e8 d9 8f a9 01 4c
RSP: 0018:ffff8801963feeb8 EFLAGS: 00010046
RAX: ffffea0000054008 RBX: ffffffff81500cc9 RCX: ffffea0000054007
RDX: ffffea0000054000 RSI: ffffffff81a635f1 RDI: ffffffff81500cc9
RBP: ffff8801963feed8 R08: ffff880191a04300 R09: ffffed003ae212a0
R10: ffffed003ae212a0 R11: ffff8801d7109507 R12: 0000000000000282
R13: 0000000000000000 R14: ffff880195d40ed8 R15: ffffffff81500cc9
FS: 00007feffa02a700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000074 CR3: 0000000195cc6000 CR4: 00000000001406e0
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.