[syzbot] [bcachefs?] KMSAN: uninit-value in bch2_dev_freespace_init

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    2ba9f676d0a2 Merge tag 'drm-next-2024-11-29' of https://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=127f3bc0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b131ba4658863ffa
dashboard link: https://syzkaller.appspot.com/bug?extid=aa2232cb0e5de0c0b56f
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/43bff3f0073a/disk-2ba9f676.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0683b9881a99/vmlinux-2ba9f676.xz
kernel image: https://storage.googleapis.com/syzbot-assets/37c30742afb0/bzImage-2ba9f676.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aa2232cb0e5de0c0b56f@xxxxxxxxxxxxxxxxxxxxxxxxx

bcachefs (loop4): marking superblocks
bcachefs (loop4): initializing freespace
=====================================================
BUG: KMSAN: uninit-value in bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
BUG: KMSAN: uninit-value in bch2_dev_freespace_init+0x1044/0x1eb0 fs/bcachefs/alloc_background.c:2232
 bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
 bch2_dev_freespace_init+0x1044/0x1eb0 fs/bcachefs/alloc_background.c:2232
 bch2_fs_freespace_init+0x599/0xb30 fs/bcachefs/alloc_background.c:2304
 bch2_fs_initialize+0x2140/0x35d0 fs/bcachefs/recovery.c:1082
 bch2_fs_start+0x77d/0xbd0 fs/bcachefs/super.c:1038
 bch2_fs_get_tree+0x13ea/0x22d0 fs/bcachefs/fs.c:2170
 vfs_get_tree+0xb1/0x5a0 fs/super.c:1814
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3507
 path_mount+0x742/0x1f10 fs/namespace.c:3834
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x722/0x810 fs/namespace.c:4034
 __ia32_sys_mount+0xe3/0x150 fs/namespace.c:4034
 ia32_sys_call+0x260e/0x4180 arch/x86/include/generated/asm/syscalls_32.h:22
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Uninit was created at:
 ___kmalloc_large_node+0x22c/0x370 mm/slub.c:4238
 __kmalloc_large_node_noprof+0x3f/0x1e0 mm/slub.c:4255
 __do_kmalloc_node mm/slub.c:4271 [inline]
 __kmalloc_node_noprof+0xc96/0x1250 mm/slub.c:4289
 __kvmalloc_node_noprof+0xc0/0x2d0 mm/util.c:650
 btree_node_data_alloc fs/bcachefs/btree_cache.c:153 [inline]
 __bch2_btree_node_mem_alloc+0x2be/0xa80 fs/bcachefs/btree_cache.c:198
 bch2_fs_btree_cache_init+0x4e4/0xb50 fs/bcachefs/btree_cache.c:653
 bch2_fs_alloc fs/bcachefs/super.c:917 [inline]
 bch2_fs_open+0x4d3a/0x5b40 fs/bcachefs/super.c:2065
 bch2_fs_get_tree+0x983/0x22d0 fs/bcachefs/fs.c:2157
 vfs_get_tree+0xb1/0x5a0 fs/super.c:1814
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3507
 path_mount+0x742/0x1f10 fs/namespace.c:3834
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x722/0x810 fs/namespace.c:4034
 __ia32_sys_mount+0xe3/0x150 fs/namespace.c:4034
 ia32_sys_call+0x260e/0x4180 arch/x86/include/generated/asm/syscalls_32.h:22
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

CPU: 0 UID: 0 PID: 6020 Comm: syz.4.18 Not tainted 6.12.0-syzkaller-11677-g2ba9f676d0a2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
=====================================================


---
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 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