[syzbot] [fs?] [mm?] KCSAN: data-race in xas_create / xas_find (10)

[syzbot] [fs?] [mm?] KCSAN: data-race in xas_create / xas_find (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    a804c5742bff Merge tag 'lsm-pr-20261016' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10762231580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e0a09745349d136e
dashboard link: https://syzkaller.appspot.com/bug?extid=73641b60a3bc11dfca8c
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/171f09113e28/disk-a804c574.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0f8812b149fb/vmlinux-a804c574.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6349a85938ab/bzImage-a804c574.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+73641b60a3bc11dfca8c@syzkaller.appspotmail.com

loop6: detected capacity change from 0 to 1024
EXT4-fs: Ignoring removed i_version option
EXT4-fs (loop6): Unsupported encryption level 6
==================================================================
BUG: KCSAN: data-race in xas_create / xas_find

write to 0xffff88811a8efda9 of 1 bytes by task 6715 on cpu 1:
 xas_expand lib/xarray.c:620 [inline]
 xas_create+0x685/0xbf0 lib/xarray.c:661
 xas_store+0x6f/0xce0 lib/xarray.c:795
 __filemap_add_folio+0x647/0x910 mm/filemap.c:915
 filemap_add_folio+0x1cd/0x380 mm/filemap.c:972
 page_cache_ra_unbounded+0x1a4/0x3a0 mm/readahead.c:293
 do_page_cache_ra mm/readahead.c:348 [inline]
 force_page_cache_ra+0x190/0x1d0 mm/readahead.c:378
 page_cache_sync_ra+0x11d/0x560 mm/readahead.c:602
 filemap_get_pages+0x2f2/0x1360 mm/filemap.c:2714
 filemap_read+0x21c/0xad0 mm/filemap.c:2824
 blkdev_read_iter+0x21e/0x2d0 block/fops.c:838
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 x64_sys_call+0x2135/0x2550 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a8efda9 of 1 bytes by task 6813 on cpu 0:
 xas_find+0x360/0x3e0 lib/xarray.c:1421
 find_get_entry mm/filemap.c:2085 [inline]
 find_lock_entries+0xd4/0x6b0 mm/filemap.c:2189
 mapping_try_invalidate+0xc7/0x430 mm/truncate.c:545
 invalidate_mapping_pages+0x27/0x40 mm/truncate.c:602
 invalidate_bdev+0x58/0x70 block/bdev.c:101
 __ext4_fill_super fs/ext4/super.c:5840 [inline]
 ext4_fill_super+0x2cd3/0x37c0 fs/ext4/super.c:5865
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1883
 get_tree_bdev+0x1f/0x30 fs/super.c:1906
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5897
 vfs_get_tree+0x57/0x1d0 fs/super.c:1943
 fc_mount fs/namespace.c:1282 [inline]
 do_new_mount_fc fs/namespace.c:3910 [inline]
 do_new_mount+0x288/0x730 fs/namespace.c:3986
 path_mount+0x4ad/0xb90 fs/namespace.c:4337
 do_mount fs/namespace.c:4350 [inline]
 __do_sys_mount fs/namespace.c:4565 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4542
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4542
 x64_sys_call+0xc3b/0x2550 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x03 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6813 Comm: syz.6.569 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
==================================================================


---
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@googlegroups.com.

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