WARNING: kmalloc bug in get_valid_checkpoint

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 008464a9360e Merge branch 'for-linus' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15f3a077800000
kernel config: https://syzkaller.appspot.com/x/.config?x=31f4b3733894ef79
dashboard link: https://syzkaller.appspot.com/bug?extid=ef4e8fc3a06e9019bb40
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=15499a97800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ef4e8f...@syzkaller.appspotmail.com

IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
IPVS: ftp: loaded support on port[0] = 21
F2FS-fs (loop1): Magic Mismatch, valid(0xf2f52010) - read(0x0)
F2FS-fs (loop1): Can't find valid F2FS filesystem in 1th superblock
WARNING: CPU: 1 PID: 4572 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70
mm/slab_common.c:996
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4572 Comm: syz-executor1 Not tainted 4.17.0-rc4+ #40
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1b9/0x294 lib/dump_stack.c:113
IPVS: ftp: loaded support on port[0] = 21
panic+0x22f/0x4de kernel/panic.c:184
__warn.cold.8+0x163/0x1b3 kernel/panic.c:536
report_bug+0x252/0x2d0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
F2FS-fs (loop0): Magic Mismatch, valid(0xf2f52010) - read(0x0)
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock
RIP: 0010:kmalloc_slab+0x56/0x70 mm/slab_common.c:996
RSP: 0018:ffff8801ae926e08 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8801b21c9540 RCX: ffffffff82f163e4
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000001e3a030000
RBP: ffff8801ae926e08 R08: ffff8801b26a0040 R09: ffffed003b5e46c2
R10: ffffed003b5e46c2 R11: ffff8801daf23613 R12: 0000001e3a030000
R13: ffff8801b21ca298 R14: 0000000000000000 R15: 00000000014080c0
__do_kmalloc mm/slab.c:3713 [inline]
__kmalloc+0x25/0x760 mm/slab.c:3727
kmalloc include/linux/slab.h:517 [inline]
f2fs_kmalloc fs/f2fs/f2fs.h:2534 [inline]
f2fs_kzalloc fs/f2fs/f2fs.h:2540 [inline]
get_valid_checkpoint+0x37f/0x1e90 fs/f2fs/checkpoint.c:805
F2FS-fs (loop0): Failed to get valid F2FS checkpoint
F2FS-fs (loop0): Magic Mismatch, valid(0xf2f52010) - read(0x0)
f2fs_fill_super+0x318f/0x7bf0 fs/f2fs/super.c:2768
F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock
F2FS-fs (loop0): Failed to get valid F2FS checkpoint
F2FS-fs (loop7): Magic Mismatch, valid(0xf2f52010) - read(0x0)
F2FS-fs (loop7): Can't find valid F2FS filesystem in 1th superblock
mount_bdev+0x30c/0x3e0 fs/super.c:1164
f2fs_mount+0x34/0x40 fs/f2fs/super.c:3020
mount_fs+0xae/0x328 fs/super.c:1267
vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
vfs_kern_mount fs/namespace.c:1027 [inline]
do_new_mount fs/namespace.c:2518 [inline]
do_mount+0x564/0x3070 fs/namespace.c:2848
ksys_mount+0x12d/0x140 fs/namespace.c:3064
__do_sys_mount fs/namespace.c:3078 [inline]
__se_sys_mount fs/namespace.c:3075 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3075
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4583aa
RSP: 002b:00007f33f012aba8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000020000040 RCX: 00000000004583aa
RDX: 0000000020000040 RSI: 0000000020000080 RDI: 00007f33f012abf0
RBP: 0000000000000001 R08: 00000000200000c0 R09: 0000000020000040
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000001 R14: 00000000006fe2d0 R15: 0000000000000000
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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