[syzbot] [v9fs?] KMSAN: uninit-value in v9fs_evict_inode

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    66a27abac311 Merge tag 'powerpc-6.9-1' of git://git.kernel..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=147b32a5180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=48bb382b96e7eda7
dashboard link: https://syzkaller.appspot.com/bug?extid=eb83fe1cce5833cd66a0
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12598006180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=105d8aa5180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/37968fa0451e/disk-66a27aba.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5b288c5c3088/vmlinux-66a27aba.xz
kernel image: https://storage.googleapis.com/syzbot-assets/792ddbf8146d/bzImage-66a27aba.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eb83fe1cce5833cd66a0@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in fscache_relinquish_cookie include/linux/fscache.h:307 [inline]
BUG: KMSAN: uninit-value in v9fs_evict_inode+0x109/0x130 fs/9p/vfs_inode.c:356
 fscache_relinquish_cookie include/linux/fscache.h:307 [inline]
 v9fs_evict_inode+0x109/0x130 fs/9p/vfs_inode.c:356
 evict+0x3ae/0xa60 fs/inode.c:667
 iput_final fs/inode.c:1741 [inline]
 iput+0x9ca/0xe10 fs/inode.c:1767
 iget_failed+0x15e/0x180 fs/bad_inode.c:248
 v9fs_fid_iget_dotl+0x375/0x570 fs/9p/vfs_inode_dotl.c:96
 v9fs_get_inode_from_fid fs/9p/v9fs.h:230 [inline]
 v9fs_mount+0xc02/0x12b0 fs/9p/vfs_super.c:142
 legacy_get_tree+0x114/0x290 fs/fs_context.c:662
 vfs_get_tree+0xa7/0x570 fs/super.c:1779
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3352
 path_mount+0x742/0x1f20 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x725/0x810 fs/namespace.c:3875
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:3875
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was created at:
 __alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 alloc_slab_page mm/slub.c:2175 [inline]
 allocate_slab mm/slub.c:2338 [inline]
 new_slab+0x2de/0x1400 mm/slub.c:2391
 ___slab_alloc+0x1184/0x33d0 mm/slub.c:3525
 __slab_alloc mm/slub.c:3610 [inline]
 __slab_alloc_node mm/slub.c:3663 [inline]
 slab_alloc_node mm/slub.c:3835 [inline]
 kmem_cache_alloc_lru+0x6d7/0xbe0 mm/slub.c:3864
 alloc_inode_sb include/linux/fs.h:3089 [inline]
 v9fs_alloc_inode+0x62/0x130 fs/9p/vfs_inode.c:228
 alloc_inode+0x86/0x460 fs/inode.c:261
 iget_locked+0x2bf/0xee0 fs/inode.c:1280
 v9fs_fid_iget_dotl+0x7f/0x570 fs/9p/vfs_inode_dotl.c:62
 v9fs_get_inode_from_fid fs/9p/v9fs.h:230 [inline]
 v9fs_mount+0xc02/0x12b0 fs/9p/vfs_super.c:142
 legacy_get_tree+0x114/0x290 fs/fs_context.c:662
 vfs_get_tree+0xa7/0x570 fs/super.c:1779
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3352
 path_mount+0x742/0x1f20 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x725/0x810 fs/namespace.c:3875
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:3875
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

CPU: 1 PID: 5014 Comm: syz-executor406 Not tainted 6.8.0-syzkaller-11136-g66a27abac311 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
=====================================================


---
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@xxxxxxxxxxxxxxxx.

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