[syzbot] [bcachefs?] KMSAN: uninit-value in __bch2_write_index

[syzbot <syzbot+fd3ccb331eb21f05d13b@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    3d25a941ea50 Merge tag 'block-6.9-20240503' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1206a590980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bbf567496022057b
dashboard link: https://syzkaller.appspot.com/bug?extid=fd3ccb331eb21f05d13b
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/c64084cbf7db/disk-3d25a941.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8250d04a440c/vmlinux-3d25a941.xz
kernel image: https://storage.googleapis.com/syzbot-assets/244d4cfb55f3/bzImage-3d25a941.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fd3ccb331eb21f05d13b@syzkaller.appspotmail.com

bcachefs (loop2): snapshots_read... done
bcachefs (loop2): journal_replay... done
bcachefs (loop2): resume_logged_ops... done
bcachefs (loop2): going read-write
bcachefs (loop2): done starting filesystem
=====================================================
BUG: KMSAN: uninit-value in find_next_bit include/linux/find.h:64 [inline]
BUG: KMSAN: uninit-value in __bch2_write_index+0x277b/0x2bd0 fs/bcachefs/io_write.c:543
 find_next_bit include/linux/find.h:64 [inline]
 __bch2_write_index+0x277b/0x2bd0 fs/bcachefs/io_write.c:543
 bch2_write_data_inline fs/bcachefs/io_write.c:1538 [inline]
 bch2_write+0x1a13/0x1b40 fs/bcachefs/io_write.c:1606
 closure_queue include/linux/closure.h:257 [inline]
 closure_call include/linux/closure.h:390 [inline]
 bch2_writepage_do_io fs/bcachefs/fs-io-buffered.c:468 [inline]
 bch2_writepages+0x24a/0x3c0 fs/bcachefs/fs-io-buffered.c:660
 do_writepages+0x427/0xc30 mm/page-writeback.c:2612
 filemap_fdatawrite_wbc+0x1d8/0x270 mm/filemap.c:397
 __filemap_fdatawrite_range mm/filemap.c:430 [inline]
 filemap_write_and_wait_range+0x169/0x420 mm/filemap.c:685
 bchfs_truncate+0xa58/0x1420
 bch2_setattr+0x29f/0x2f0 fs/bcachefs/fs.c:882
 notify_change+0x1a07/0x1af0 fs/attr.c:497
 do_truncate+0x22a/0x2b0 fs/open.c:65
 vfs_truncate+0x5d4/0x680 fs/open.c:111
 do_sys_truncate+0x107/0x250 fs/open.c:134
 __do_compat_sys_truncate fs/open.c:152 [inline]
 __se_compat_sys_truncate fs/open.c:150 [inline]
 __ia32_compat_sys_truncate+0x6c/0xa0 fs/open.c:150
 ia32_sys_call+0x24d4/0x40a0 arch/x86/include/generated/asm/syscalls_32.h:93
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0xb4/0x120 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:
 __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+0x6d3/0xbe0 mm/slub.c:3852
 mempool_alloc_slab+0x36/0x50 mm/mempool.c:565
 mempool_init_node+0x202/0x4d0 mm/mempool.c:217
 mempool_init+0x57/0x70 mm/mempool.c:246
 mempool_init_slab_pool include/linux/mempool.h:68 [inline]
 bioset_init+0x271/0xac0 block/bio.c:1752
 bch2_fs_fs_io_buffered_init+0x4a/0xc0 fs/bcachefs/fs-io-buffered.c:1156
 bch2_fs_alloc+0x3c71/0x4210 fs/bcachefs/super.c:937
 bch2_fs_open+0xdde/0x1670 fs/bcachefs/super.c:2081
 bch2_mount+0x90d/0x1d90 fs/bcachefs/fs.c:1903
 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
 __ia32_sys_mount+0xe3/0x150 fs/namespace.c:3875
 ia32_sys_call+0x3a9a/0x40a0 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+0xb4/0x120 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 PID: 17163 Comm: syz-executor.2 Not tainted 6.9.0-rc6-syzkaller-00227-g3d25a941ea50 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


---
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