syzbot

EXT4-fs (loop4): Remounting filesystem read-only
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:4867!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 432 Comm: syz.4.21 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:ext4_mb_release_inode_pa+0xa73/0xa80 fs/ext4/mballoc.c:4867
Code: e2 07 80 c2 03 38 c2 0f 8c 2c fe ff ff 4c 89 f7 89 cb e8 f0 36 c8 ff 89 d9 e9 1b fe ff ff e8 34 ac 82 ff 0f 0b e8 2d ac 82 ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0000:ffffc90000d16aa0 EFLAGS: 00010293
RAX: ffffffff81eea8f3 RBX: 0000000000000503 RCX: ffff88811a790000
RDX: 0000000000000000 RSI: 0000000000000060 RDI: 0000000000000000
RBP: ffffc90000d16bf0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520001a2d70 R12: 1ffff920001a2d6c
R13: dffffc0000000000 R14: 0000000000000060 R15: 0000000000000000
FS:  00007fe3298c96c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe32043f000 CR3: 000000011b0d5000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_mb_discard_group_preallocations+0xbdb/0xe20 fs/ext4/mballoc.c:5013
 ext4_mb_discard_preallocations fs/ext4/mballoc.c:5582 [inline]
 ext4_mb_discard_preallocations_should_retry+0x15a/0x5e0 fs/ext4/mballoc.c:5603
 ext4_mb_new_blocks+0x2f60/0x4070 fs/ext4/mballoc.c:5806
 ext4_alloc_branch fs/ext4/indirect.c:340 [inline]
 ext4_ind_map_blocks+0xdd1/0x2040 fs/ext4/indirect.c:635
 ext4_map_blocks+0x97a/0x1a80 fs/ext4/inode.c:683
 _ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:824
 ext4_get_block+0x39/0x50 fs/ext4/inode.c:841
 ext4_block_write_begin+0x59b/0x1240 fs/ext4/inode.c:1126
 ext4_write_begin+0x614/0xfc0 fs/ext4/ext4_jbd2.h:-1
 generic_perform_write+0x32d/0x740 mm/filemap.c:3915
 ext4_buffered_write_iter+0x38f/0x690 fs/ext4/file.c:285
 ext4_file_write_iter+0x4b2/0x1540 fs/ext4/file.c:-1
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x65a/0xb30 fs/read_write.c:861
 vfs_writev+0x339/0x5f0 fs/read_write.c:934
 do_writev+0x14e/0x2c0 fs/read_write.c:977
 __do_sys_writev fs/read_write.c:1050 [inline]
 __se_sys_writev fs/read_write.c:1047 [inline]
 __x64_sys_writev+0x7d/0x90 fs/read_write.c:1047
 x64_sys_call+0xad/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:21
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe32899ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe3298c9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fe328c15fa0 RCX: 00007fe32899ce59
RDX: 0000000000000001 RSI: 0000200000000140 RDI: 0000000000000005
RBP: 00007fe328a32e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe328c16038 R14: 00007fe328c15fa0 R15: 00007ffd46f64d88
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_mb_release_inode_pa+0xa73/0xa80 fs/ext4/mballoc.c:4867
Code: e2 07 80 c2 03 38 c2 0f 8c 2c fe ff ff 4c 89 f7 89 cb e8 f0 36 c8 ff 89 d9 e9 1b fe ff ff e8 34 ac 82 ff 0f 0b e8 2d ac 82 ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0000:ffffc90000d16aa0 EFLAGS: 00010293
RAX: ffffffff81eea8f3 RBX: 0000000000000503 RCX: ffff88811a790000
RDX: 0000000000000000 RSI: 0000000000000060 RDI: 0000000000000000
RBP: ffffc90000d16bf0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520001a2d70 R12: 1ffff920001a2d6c
R13: dffffc0000000000 R14: 0000000000000060 R15: 0000000000000000
FS:  00007fe3298c96c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe32043f000 CR3: 000000011b0d5000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400