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

[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+3735a85c5c610415e2b6@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>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

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

[Christoph Hellwig]

This got fixed in vmalloc by adding GFP_NOLOCKDEP to the allow vmalloc
flags.

Is syzbot now also running on linux-next?

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

[Aleksandr Nogikh]

On Mon, Nov 24, 2025 at 8:10 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> This got fixed in vmalloc by adding GFP_NOLOCKDEP to the allow vmalloc
> flags.
>
> Is syzbot now also running on linux-next?
>

Linux-next has been one of the targets for a very long time already.

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

[Christoph Hellwig]

On Mon, Nov 24, 2025 at 09:43:47AM +0100, Aleksandr Nogikh wrote:
> On Mon, Nov 24, 2025 at 8:10 AM Christoph Hellwig <hch@infradead.org> wrote:
> >
> > This got fixed in vmalloc by adding GFP_NOLOCKDEP to the allow vmalloc
> > flags.
> >
> > Is syzbot now also running on linux-next?
> >
> 
> Linux-next has been one of the targets for a very long time already.

Ok, I'm not updatodate then.  How do we deal with the fact that no
specific commit fixed an issue, but a commit causing a problem got
replaced with a different one in linux-next?

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

[Aleksandr Nogikh]

On Mon, Nov 24, 2025 at 9:46 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Mon, Nov 24, 2025 at 09:43:47AM +0100, Aleksandr Nogikh wrote:
> > On Mon, Nov 24, 2025 at 8:10 AM Christoph Hellwig <hch@infradead.org> wrote:
> > >
> > > This got fixed in vmalloc by adding GFP_NOLOCKDEP to the allow vmalloc
> > > flags.
> > >
> > > Is syzbot now also running on linux-next?
> > >
> >
> > Linux-next has been one of the targets for a very long time already.
>
> Ok, I'm not updatodate then.  How do we deal with the fact that no
> specific commit fixed an issue, but a commit causing a problem got
> replaced with a different one in linux-next?

That's indeed a difficult question within our current bug tracking
model. For now, the best option would be to just invalidate the report
so that it does not stay open:
#syz invalid

We have a backlog issue regarding selecting a better approach:
https://github.com/google/syzkaller/issues/1878

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

[Christoph Hellwig]

#syz invalid

Fixed by replacing the offending commit with a fixed one in
linux-next that allows GFP_NOLOCKDEP.

On Sat, Nov 22, 2025 at 09:08:24PM -0800, syzbot wrote:
> 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+3735a85c5c610415e2b6@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>
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup
> 
---end quoted text---