[syzbot] [bcachefs?] KMSAN: uninit-value in bch2_btree_node_check_topology

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    7758b206117d Merge tag 'tracefs-v6.12-rc6' of git://git.ke..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13e72e30580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6fdf74cce377223b
dashboard link: https://syzkaller.appspot.com/bug?extid=494bcd3631a9f6759f91
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=13a0df40580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15e1f6a7980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cff7adedd889/disk-7758b206.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c3babec78429/vmlinux-7758b206.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9de747183951/bzImage-7758b206.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/c2654a9124db/mount_1.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+494bcd3631a9f6759f91@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: KMSAN: uninit-value in bch2_btree_node_check_topology+0x12cc/0x2e40 fs/bcachefs/btree_update_interior.c:96
 bch2_btree_node_check_topology+0x12cc/0x2e40 fs/bcachefs/btree_update_interior.c:96
 btree_split_insert_keys+0x4fd/0x630 fs/bcachefs/btree_update_interior.c:1573
 btree_split+0xdc4/0x98e0 fs/bcachefs/btree_update_interior.c:1664
 bch2_btree_insert_node+0xaba/0x2810 fs/bcachefs/btree_update_interior.c:1837
 bch2_btree_node_rewrite+0x10f8/0x1930 fs/bcachefs/btree_update_interior.c:2164
 async_btree_node_rewrite_trans fs/bcachefs/btree_update_interior.c:2230 [inline]
 async_btree_node_rewrite_work+0x485/0x1710 fs/bcachefs/btree_update_interior.c:2243
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
 ___kmalloc_large_node+0x22c/0x370 mm/slub.c:4219
 __kmalloc_large_node_noprof+0x3f/0x1e0 mm/slub.c:4236
 __do_kmalloc_node mm/slub.c:4252 [inline]
 __kmalloc_node_noprof+0x9d6/0xf50 mm/slub.c:4270
 __kvmalloc_node_noprof+0xc0/0x2d0 mm/util.c:658
 btree_node_data_alloc fs/bcachefs/btree_cache.c:125 [inline]
 bch2_btree_node_mem_alloc+0xa68/0x2e30 fs/bcachefs/btree_cache.c:807
 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:325 [inline]
 bch2_btree_reserve_get+0x37f/0x2290 fs/bcachefs/btree_update_interior.c:554
 bch2_btree_update_start+0x1af9/0x2d60 fs/bcachefs/btree_update_interior.c:1252
 bch2_btree_node_rewrite+0x1da/0x1930 fs/bcachefs/btree_update_interior.c:2142
 async_btree_node_rewrite_trans fs/bcachefs/btree_update_interior.c:2230 [inline]
 async_btree_node_rewrite_work+0x485/0x1710 fs/bcachefs/btree_update_interior.c:2243
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
 kthread+0x3e2/0x540 kernel/kthread.c:389
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

CPU: 0 UID: 0 PID: 3761 Comm: kworker/u8:13 Not tainted 6.12.0-rc6-syzkaller-00099-g7758b206117d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: btree_node_rewrite async_btree_node_rewrite_work
=====================================================


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