Re: [syzbot] [ext4?] WARNING in bdev_getblk

[syzbot <syzbot+01ef7a8da81a975e1ccd@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    835244aba90d Add linux-next specific files for 20250709
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10535a8c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8396fd456733c122
dashboard link: https://syzkaller.appspot.com/bug?extid=01ef7a8da81a975e1ccd
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=115c40f0580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11856a8c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e5c5711c47f9/disk-835244ab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dd2453f9f672/vmlinux-835244ab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a81cc03651e7/bzImage-835244ab.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e3888e058fbc/mount_0.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=12856a8c580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+01ef7a8da81a975e1ccd@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: fs/buffer.c:1125 at __getblk_slow fs/buffer.c:1125 [inline], CPU#0: syz-executor261/5880
WARNING: fs/buffer.c:1125 at bdev_getblk+0x580/0x660 fs/buffer.c:1461, CPU#0: syz-executor261/5880
Modules linked in:
CPU: 0 UID: 0 PID: 5880 Comm: syz-executor261 Not tainted 6.16.0-rc5-next-20250709-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__getblk_slow fs/buffer.c:1125 [inline]
RIP: 0010:bdev_getblk+0x580/0x660 fs/buffer.c:1461
Code: 26 fb ff ff e8 81 ee 78 ff 48 c7 c7 20 08 9a 8b 48 c7 c6 02 1b a0 8d 4c 89 fa 4c 89 e9 e8 38 d7 e0 fe eb bd e8 61 ee 78 ff 90 <0f> 0b 90 48 b8 00 00 00 00 00 fc ff df 41 80 3c 07 00 74 08 48 89
RSP: 0018:ffffc9000403f620 EFLAGS: 00010293
RAX: ffffffff8246c6ff RBX: ffff888022d0b998 RCX: ffff888078b31e00
RDX: 0000000000000000 RSI: 0000000000000400 RDI: 0000000000000000
RBP: 0000000000000400 R08: ffff888078b31e00 R09: 0000000000000003
R10: 0000000000000406 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888022d0b980 R14: 0000000000000400 R15: 1ffff110045a1733
FS:  000055558d712380(0000) GS:ffff888125bd4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5b0e5d6000 CR3: 00000000227ea000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ext4_sb_breadahead_unmovable+0x6f/0xf0 fs/ext4/super.c:270
 __ext4_get_inode_loc+0xcc9/0x1040 fs/ext4/inode.c:4879
 __ext4_get_inode_loc_noinmem fs/ext4/inode.c:4909 [inline]
 __ext4_iget+0x450/0x4260 fs/ext4/inode.c:5168
 __ext4_fill_super fs/ext4/super.c:5500 [inline]
 ext4_fill_super+0x4592/0x6080 fs/ext4/super.c:5724
 get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1681
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3805
 do_mount fs/namespace.c:4133 [inline]
 __do_sys_mount fs/namespace.c:4344 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4321
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f457044b7da
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd924f6f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd924f6f70 RCX: 00007f457044b7da
RDX: 0000200000000040 RSI: 0000200000000000 RDI: 00007ffd924f6f70
RBP: 0000200000000000 R08: 00007ffd924f6fb0 R09: 00007ffd924f6fb0
R10: 000000000000088e R11: 0000000000000246 R12: 0000200000000040
R13: 00007ffd924f6fb0 R14: 0000000000000003 R15: 000000000000088e
 </TASK>


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