[v6.6] WARNING in v9fs_fid_get_acl

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c2603c511feb Linux 6.6.93
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=179f9e82580000
kernel config: https://syzkaller.appspot.com/x/.config?x=486bade17c8c30b9
dashboard link: https://syzkaller.appspot.com/bug?extid=f8f9591a0de3737013ab
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8754f950a6e7/disk-c2603c51.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3b19332dbf63/vmlinux-c2603c51.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cb245e836038/bzImage-c2603c51.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f8f959...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 21257 at mm/page_alloc.c:4433 __alloc_pages+0x2de/0x460 mm/page_alloc.c:4433
Modules linked in:
CPU: 1 PID: 21257 Comm: syz.7.4407 Not tainted 6.6.93-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__alloc_pages+0x2de/0x460 mm/page_alloc.c:4433
Code: 0c 25 28 00 00 00 48 3b 8c 24 a0 00 00 00 0f 85 a0 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 c6 05 34 ef 61 0c 01 <0f> 0b eb a5 a9 00 00 08 00 8b 74 24 0c 75 3e 44 89 f1 81 e1 7f ff
RSP: 0018:ffffc90004bffa80 EFLAGS: 00010246
RAX: ffffc90004bffa00 RBX: 1ffff9200097ff54 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90004bffae8
RBP: ffffc90004bffb80 R08: ffffc90004bffae7 R09: 0000000000000000
R10: ffffc90004bffac0 R11: fffff5200097ff5d R12: 000000000000002a
R13: 0000000000000000 R14: 0000000000040d40 R15: dffffc0000000000
FS: 00007f93459ef6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000010a000 CR3: 000000002c5a2000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_pages_node include/linux/gfp.h:260 [inline]
__kmalloc_large_node+0x8c/0x1e0 mm/slab_common.c:1148
__do_kmalloc_node mm/slab_common.c:995 [inline]
__kmalloc+0x111/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
kzalloc include/linux/slab.h:721 [inline]
v9fs_fid_get_acl+0x4f/0xf0 fs/9p/acl.c:32
__v9fs_get_acl fs/9p/acl.c:66 [inline]
v9fs_get_acl+0x9a/0x350 fs/9p/acl.c:92
v9fs_mount+0x862/0xb40 fs/9p/vfs_super.c:181
legacy_get_tree+0xea/0x180 fs/fs_context.c:662
vfs_get_tree+0x8c/0x280 fs/super.c:1764
do_new_mount+0x24b/0xa40 fs/namespace.c:3355
do_mount fs/namespace.c:3695 [inline]
__do_sys_mount fs/namespace.c:3904 [inline]
__se_sys_mount+0x2da/0x3c0 fs/namespace.c:3881
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9344b8e929
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:00007f93459ef038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f9344db5fa0 RCX: 00007f9344b8e929
RDX: 0000200000000b80 RSI: 00002000000003c0 RDI: 0000000000000000
RBP: 00007f9344c10b39 R08: 0000200000000580 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f9344db5fa0 R15: 00007ffc0001fe38
</TASK>


---
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If you want to undo deduplication, reply with:
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15513b0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427

dashboard link: https://syzkaller.appspot.com/bug?extid=f8f9591a0de3737013ab
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16f96b0c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13513b0c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f8f959...@syzkaller.appspotmail.com

------------[ cut here ]------------

WARNING: CPU: 1 PID: 5770 at mm/page_alloc.c:4433 __alloc_pages+0x2de/0x460 mm/page_alloc.c:4433
Modules linked in:
CPU: 1 PID: 5770 Comm: syz-executor614 Not tainted 6.6.94-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__alloc_pages+0x2de/0x460 mm/page_alloc.c:4433

Code: 0c 25 28 00 00 00 48 3b 8c 24 a0 00 00 00 0f 85 a0 00 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 c6 05 96 f1 61 0c 01 <0f> 0b eb a5 a9 00 00 08 00 8b 74 24 0c 75 3e 44 89 f1 81 e1 7f ff
RSP: 0018:ffffc90003c87a80 EFLAGS: 00010246
RAX: ffffc90003c87a00 RBX: 1ffff92000790f54 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90003c87ae8
RBP: ffffc90003c87b80 R08: ffffc90003c87ae7 R09: 0000000000000000
R10: ffffc90003c87ac0 R11: fffff52000790f5d R12: 000000000000002a

R13: 0000000000000000 R14: 0000000000040d40 R15: dffffc0000000000

FS: 000055556bc00380(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000561e361bd000 CR3: 00000000307e1000 CR4: 00000000003506e0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_pages_node include/linux/gfp.h:260 [inline]
__kmalloc_large_node+0x8c/0x1e0 mm/slab_common.c:1148
__do_kmalloc_node mm/slab_common.c:995 [inline]
__kmalloc+0x111/0x240 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
kzalloc include/linux/slab.h:721 [inline]
v9fs_fid_get_acl+0x4f/0xf0 fs/9p/acl.c:32
__v9fs_get_acl fs/9p/acl.c:66 [inline]
v9fs_get_acl+0x9a/0x350 fs/9p/acl.c:92
v9fs_mount+0x862/0xb40 fs/9p/vfs_super.c:181
legacy_get_tree+0xea/0x180 fs/fs_context.c:662
vfs_get_tree+0x8c/0x280 fs/super.c:1764

do_new_mount+0x24b/0xa40 fs/namespace.c:3366
do_mount fs/namespace.c:3706 [inline]
__do_sys_mount fs/namespace.c:3915 [inline]
__se_sys_mount+0x2da/0x3c0 fs/namespace.c:3892

do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

RIP: 0033:0x7f45d525f829
Code: 48 83 c4 28 c3 e8 c7 1b 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcf3786958 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00002000000003c0 RCX: 00007f45d525f829

RDX: 0000200000000b80 RSI: 00002000000003c0 RDI: 0000000000000000

RBP: 0000200000000580 R08: 0000200000000580 R09: 00007ffcf3786990
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f45d52a5160
R13: 00007f45d52d541c R14: 00007f45d52d5404 R15: 00007ffcf3786998
</TASK>


---
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.

[syzbot]

syzbot suspects this issue could be fixed by backporting the following commit:

commit e8fe3f07a357c39d429e02ca34f740692d88967a
git tree: upstream
Author: Oleg Nesterov <ol...@redhat.com>
Date: Tue Aug 19 16:10:13 2025 +0000

9p/trans_fd: p9_fd_request: kick rx thread if EPOLLIN

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1332bd9a580000

kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=f8f9591a0de3737013ab

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16f96b0c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13513b0c580000

Please keep in mind that other backports might be required as well.

For information about bisection process see: https://goo.gl/tpsmEJ#bisection