[moderation] [fs?] [mm?] KCSAN: data-race in xas_create / xas_find_marked (7)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5635f189425e Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1705e630580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b957b77e265904d
dashboard link: https://syzkaller.appspot.com/bug?extid=39258811f6f9c7d5970c
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@kvack.org wi...@infradead.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/02c8e8934f70/disk-5635f189.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0c7f87b1c9fb/vmlinux-5635f189.xz
kernel image: https://storage.googleapis.com/syzbot-assets/27052a026e2c/bzImage-5635f189.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+392588...@syzkaller.appspotmail.com

loop8: detected capacity change from 0 to 2048
==================================================================
BUG: KCSAN: data-race in xas_create / xas_find_marked

write to 0xffff8881066af489 of 1 bytes by task 3511 on cpu 1:
xas_expand lib/xarray.c:613 [inline]
xas_create+0x666/0xbd0 lib/xarray.c:654
xas_store+0x6f/0xc90 lib/xarray.c:788
__filemap_add_folio+0x3cc/0x6f0 mm/filemap.c:916
filemap_add_folio+0x9c/0x1b0 mm/filemap.c:972
page_cache_ra_unbounded+0x175/0x310 mm/readahead.c:268
do_page_cache_ra mm/readahead.c:320 [inline]
force_page_cache_ra mm/readahead.c:349 [inline]
page_cache_sync_ra+0x252/0x670 mm/readahead.c:562
page_cache_sync_readahead include/linux/pagemap.h:1394 [inline]
filemap_get_pages+0x2c1/0x10e0 mm/filemap.c:2547
filemap_read+0x216/0x680 mm/filemap.c:2645
blkdev_read_iter+0x20e/0x2c0 block/fops.c:765
new_sync_read fs/read_write.c:488 [inline]
vfs_read+0x5dc/0x700 fs/read_write.c:569
ksys_read+0xeb/0x1b0 fs/read_write.c:712
__do_sys_read fs/read_write.c:722 [inline]
__se_sys_read fs/read_write.c:720 [inline]
__x64_sys_read+0x42/0x50 fs/read_write.c:720
x64_sys_call+0x27d3/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:1
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881066af489 of 1 bytes by task 29428 on cpu 0:
xas_find_marked+0x412/0x660 lib/xarray.c:1354
find_get_entry+0x54/0x390 mm/filemap.c:1994
filemap_get_folios_tag+0x9e/0x210 mm/filemap.c:2261
__filemap_fdatawait_range mm/filemap.c:524 [inline]
filemap_write_and_wait_range+0x138/0x2c0 mm/filemap.c:694
filemap_write_and_wait include/linux/pagemap.h:68 [inline]
sync_blockdev block/bdev.c:219 [inline]
set_blocksize+0x1d0/0x270 block/bdev.c:171
sb_set_blocksize+0x2c/0xb0 block/bdev.c:182
ext4_load_super fs/ext4/super.c:5061 [inline]
__ext4_fill_super fs/ext4/super.c:5213 [inline]
ext4_fill_super+0xdca/0x3a10 fs/ext4/super.c:5686
get_tree_bdev+0x256/0x2e0 fs/super.c:1635
ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5718
vfs_get_tree+0x56/0x1e0 fs/super.c:1800
do_new_mount+0x227/0x690 fs/namespace.c:3507
path_mount+0x49b/0xb30 fs/namespace.c:3834
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4057 [inline]
__se_sys_mount+0x27c/0x2d0 fs/namespace.c:4034
__x64_sys_mount+0x67/0x80 fs/namespace.c:4034
x64_sys_call+0x203e/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:166
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x05 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 29428 Comm: syz.8.4329 Not tainted 6.12.0-rc5-syzkaller-00176-g5635f189425e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================
EXT4-fs (loop8): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.