kernel BUG in ext4_mb_load_buddy_gfp

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7d7d1c0a Linux 4.14.232
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=170c6909d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=17ee8a0e183900d8
dashboard link: https://syzkaller.appspot.com/bug?extid=9fb6cebb68c961541029
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16a95f43d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1396f733d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9fb6ce...@syzkaller.appspotmail.com

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kernel BUG at fs/ext4/ext4.h:2849!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
EXT4-fs error (device sda1) in ext4_reserve_inode_write:5811: Out of memory
Modules linked in:
CPU: 1 PID: 7992 Comm: syz-executor018 Not tainted 4.14.232-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88809e87c540 task.stack: ffff888095950000
RIP: 0010:ext4_get_group_info fs/ext4/ext4.h:2849 [inline]
RIP: 0010:ext4_mb_load_buddy_gfp+0x10dd/0x16c0 fs/ext4/mballoc.c:1128
RSP: 0018:ffff888095957880 EFLAGS: 00010297
RAX: ffff88809e87c540 RBX: ffff888095957980 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffff8880a4752380
RBP: 00000000fffec510 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: ffff88809e87c540 R12: ffff8880a4750300
R13: ffff8882396e5270 R14: ffff8880a4752340 R15: ffff8880a4750980
FS: 00007fc5e3623700(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020e009bf CR3: 0000000008e6a000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
ext4_discard_preallocations+0x94b/0xdf0 fs/ext4/mballoc.c:4117
ext4_release_file+0x257/0x2d0 fs/ext4/file.c:96
__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x11f/0x190 kernel/task_work.c:113
exit_task_work include/linux/task_work.h:22 [inline]
do_exit+0xa44/0x2850 kernel/exit.c:868
do_group_exit+0x100/0x2e0 kernel/exit.c:965
get_signal+0x38d/0x1ca0 kernel/signal.c:2423
do_signal+0x7c/0x1550 arch/x86/kernel/signal.c:792
exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x4454e9
RSP: 002b:00007fc5e36232f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00000000004cc510 RCX: 00000000004454e9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000004cc518
RBP: 000000000049c1bc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffef9e2df6e
R13: 2f30656c69662f2e R14: 6465646165726874 R15: 00000000004cc518
Code: e8 a9 44 af ff e9 90 f8 ff ff e8 9f 0b 98 ff e9 f5 f6 ff ff e8 95 0b 98 ff 48 89 ef e8 8d 44 af ff e9 3d fb ff ff e8 83 0b 98 ff <0f> 0b e8 7c 0b 98 ff 8b 54 24 28 89 ee 4c 89 e7 e8 ce db ff ff
RIP: ext4_get_group_info fs/ext4/ext4.h:2849 [inline] RSP: ffff888095957880
RIP: ext4_mb_load_buddy_gfp+0x10dd/0x16c0 fs/ext4/mballoc.c:1128 RSP: ffff888095957880
---[ end trace 8624e86c108272a5 ]---


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