WARNING in sysfs_create_dir_ns

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 01364dad Linux 4.14.174
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1181a61de00000
kernel config: https://syzkaller.appspot.com/x/.config?x=664dd71881ab2b2d
dashboard link: https://syzkaller.appspot.com/bug?extid=f753fb6339ff7eaa0a98
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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+f753fb...@syzkaller.appspotmail.com

slab_pre_alloc_hook mm/slab.h:421 [inline]
slab_alloc mm/slab.c:3376 [inline]
__do_kmalloc mm/slab.c:3718 [inline]
__kmalloc+0x2e9/0x7c0 mm/slab.c:3729
kmalloc include/linux/slab.h:493 [inline]
kzalloc include/linux/slab.h:661 [inline]
kobject_get_path+0xb0/0x180 lib/kobject.c:154
input_devices_seq_show+0x2a/0x6d0 drivers/input/input.c:1145
------------[ cut here ]------------
seq_read+0xaa7/0x1160 fs/seq_file.c:272
WARNING: CPU: 0 PID: 11866 at fs/sysfs/dir.c:30 sysfs_warn_dup.cold+0x17/0x2d fs/sysfs/dir.c:30
Kernel panic - not syncing: panic_on_warn set ...

proc_reg_read+0xf2/0x160 fs/proc/inode.c:217
__vfs_read+0xe4/0x610 fs/read_write.c:411
vfs_read+0x131/0x330 fs/read_write.c:447
SYSC_read fs/read_write.c:574 [inline]
SyS_read+0xf2/0x210 fs/read_write.c:567
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007f11c7ef8c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f11c7ef96d4 RCX: 000000000045c849
RDX: 0000000000001000 RSI: 0000000020001040 RDI: 0000000000000004
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000005
R13: 0000000000000870 R14: 00000000004cb293 R15: 0000000000000005
CPU: 0 PID: 11866 Comm: syz-executor.2 Not tainted 4.14.174-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x13e/0x194 lib/dump_stack.c:58
panic+0x1f9/0x42d kernel/panic.c:183
__warn.cold+0x2f/0x30 kernel/panic.c:547
report_bug+0x20a/0x248 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:177 [inline]
fixup_bug arch/x86/kernel/traps.c:172 [inline]
do_error_trap+0x195/0x2d0 arch/x86/kernel/traps.c:295
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963
RIP: 0010:sysfs_warn_dup.cold+0x17/0x2d fs/sysfs/dir.c:30
RSP: 0018:ffff88805317f7c8 EFLAGS: 00010282
RAX: 000000000000004a RBX: ffff888088c40b50 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff81491370 RDI: ffffed100a62feef
RBP: ffff888053c7c600 R08: 000000000000004a R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888218ee19a0
R13: ffff888099603a00 R14: ffff888088c40b68 R15: ffff888094827840
sysfs_create_dir_ns+0x16f/0x1d0 fs/sysfs/dir.c:59
create_dir lib/kobject.c:71 [inline]
kobject_add_internal+0x27f/0x830 lib/kobject.c:229
kobject_add_varg lib/kobject.c:364 [inline]
kobject_add+0x11f/0x180 lib/kobject.c:409
device_add+0x36a/0x1400 drivers/base/core.c:1869
device_create_groups_vargs+0x1dc/0x250 drivers/base/core.c:2513
device_create_vargs+0x3a/0x50 drivers/base/core.c:2553
bdi_register_va.part.0+0x35/0x650 mm/backing-dev.c:879
bdi_register_va+0x63/0x80 mm/backing-dev.c:895
super_setup_bdi_name+0x123/0x220 fs/super.c:1297
fuse_bdi_init fs/fuse/inode.c:990 [inline]
fuse_fill_super+0x92d/0x1620 fs/fuse/inode.c:1110
mount_bdev+0x2bc/0x370 fs/super.c:1134
mount_fs+0x92/0x2a0 fs/super.c:1237
vfs_kern_mount.part.0+0x5b/0x3c0 fs/namespace.c:1046
vfs_kern_mount fs/namespace.c:1036 [inline]
do_new_mount fs/namespace.c:2549 [inline]
do_mount+0x3c9/0x24f0 fs/namespace.c:2879
SYSC_mount fs/namespace.c:3095 [inline]
SyS_mount+0xa8/0x120 fs/namespace.c:3072
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c849
RSP: 002b:00007fb969727c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb9697286d4 RCX: 000000000045c849
RDX: 00000000200003c0 RSI: 0000000020000140 RDI: 0000000020000340
RBP: 000000000076bf00 R08: 0000000020000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: 0000000000000753 R14: 00000000004ca0f9 R15: 000000000000000a
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

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