[syzbot] [xfs?] WARNING: kmalloc bug in xfs_buf_alloc

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fe4d0dea039f Add linux-next specific files for 20251119
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15917692580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f20a6db7594dcad7
dashboard link: https://syzkaller.appspot.com/bug?extid=3735a85c5c610415e2b6
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1588ba12580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16b00514580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ce4f26d91a01/disk-fe4d0dea.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6c9b53acf521/vmlinux-fe4d0dea.xz
kernel image: https://storage.googleapis.com/syzbot-assets/64d37d01cd64/bzImage-fe4d0dea.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/28a73d2f6731/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=12b00514580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3735a8...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
XFS (loop0): Mounting V5 Filesystem c496e05e-540d-4c72-b591-04d79d8b4eeb
XFS (loop0): Ending clean mount
------------[ cut here ]------------
Unexpected gfp: 0x1000000 (__GFP_NOLOCKDEP). Fixing up to gfp: 0x2dc0 (GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN). Fix your code!
WARNING: mm/vmalloc.c:3940 at vmalloc_fix_flags+0x9c/0xe0 mm/vmalloc.c:3939, CPU#0: syz.0.17/6023
Modules linked in:
CPU: 0 UID: 0 PID: 6023 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:vmalloc_fix_flags+0x9c/0xe0 mm/vmalloc.c:3939
Code: 81 e6 1f 52 ae ff 89 74 24 30 81 e3 e0 ad 51 00 89 5c 24 20 90 48 c7 c7 60 db 76 8b 4c 89 fa 89 d9 4d 89 f0 e8 05 8d 6c ff 90 <0f> 0b 90 90 8b 44 24 20 48 c7 04 24 0e 36 e0 45 4b c7 04 2c 00 00
RSP: 0018:ffffc90002f0eb00 EFLAGS: 00010246
RAX: 1961bedde0732e00 RBX: 0000000000002dc0 RCX: ffff888031575b80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc90002f0eb98 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bba708 R12: 1ffff920005e1d60
R13: dffffc0000000000 R14: ffffc90002f0eb20 R15: ffffc90002f0eb30
FS: 000055556e61c500(0000) GS:ffff888125ebc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000010000 CR3: 000000007f42c000 CR4: 00000000003526f0
Call Trace:
<TASK>
__vmalloc_noprof+0xf2/0x120 mm/vmalloc.c:4126
xfs_buf_alloc_backing_mem fs/xfs/xfs_buf.c:239 [inline]
xfs_buf_alloc+0xe7b/0x1d50 fs/xfs/xfs_buf.c:312
xfs_buf_find_insert+0xab/0x1470 fs/xfs/xfs_buf.c:502
xfs_buf_get_map+0x1288/0x1880 fs/xfs/xfs_buf.c:606
xfs_buf_get fs/xfs/xfs_buf.h:247 [inline]
xfs_attr_rmtval_set_value+0x3ac/0x6d0 fs/xfs/libxfs/xfs_attr_remote.c:538
xfs_attr_rmtval_alloc fs/xfs/libxfs/xfs_attr.c:645 [inline]
xfs_attr_set_iter+0x332/0x4ba0 fs/xfs/libxfs/xfs_attr.c:866
xfs_attr_finish_item+0xed/0x320 fs/xfs/xfs_attr_item.c:506
xfs_defer_finish_one+0x5a8/0xd00 fs/xfs/libxfs/xfs_defer.c:595
xfs_defer_finish_noroll+0x8d8/0x12a0 fs/xfs/libxfs/xfs_defer.c:707
xfs_trans_commit+0x10b/0x1c0 fs/xfs/xfs_trans.c:921
xfs_attr_set+0xdc6/0x1210 fs/xfs/libxfs/xfs_attr.c:1150
xfs_xattr_set+0x14d/0x250 fs/xfs/xfs_xattr.c:186
__vfs_setxattr+0x43c/0x480 fs/xattr.c:200
__vfs_setxattr_noperm+0x12d/0x660 fs/xattr.c:234
vfs_setxattr+0x16b/0x2f0 fs/xattr.c:321
do_setxattr fs/xattr.c:636 [inline]
filename_setxattr+0x274/0x600 fs/xattr.c:665
path_setxattrat+0x364/0x3a0 fs/xattr.c:713
__do_sys_lsetxattr fs/xattr.c:754 [inline]
__se_sys_lsetxattr fs/xattr.c:750 [inline]
__x64_sys_lsetxattr+0xbf/0xe0 fs/xattr.c:750
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f865218f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd621091f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00007f86523e5fa0 RCX: 00007f865218f749
RDX: 0000200000000480 RSI: 00002000000000c0 RDI: 0000200000000100
RBP: 00007f8652213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000fe37 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f86523e5fa0 R14: 00007f86523e5fa0 R15: 0000000000000005
</TASK>


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