[moderation] [mm?] KCSAN: data-race in filemap_read_folio / filemap_read_folio (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e69c7c175115 Merge tag 'timers_urgent_for_v6.18_rc8' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1331fcb4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=655255e3ef31c19b
dashboard link: https://syzkaller.appspot.com/bug?extid=42dd0c0b889a6183edde
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [ak...@linux-foundation.org da...@kernel.org j...@ziepe.ca jhub...@nvidia.com linux-...@vger.kernel.org linu...@kvack.org pet...@redhat.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/04640737f2d9/disk-e69c7c17.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4626b4f723cf/vmlinux-e69c7c17.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ec1d58093b2b/bzImage-e69c7c17.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+42dd0c...@syzkaller.appspotmail.com

Buffer I/O error on dev loop3, logical block 2072, async page read
==================================================================
BUG: KCSAN: data-race in filemap_read_folio / filemap_read_folio

read-write to 0xffff888117725760 of 4 bytes by task 6134 on cpu 0:
shrink_readahead_size_eio mm/filemap.c:2386 [inline]
filemap_read_folio+0xea/0x110 mm/filemap.c:2456
filemap_fault+0x58f/0xb60 mm/filemap.c:3581
__do_fault+0xbc/0x200 mm/memory.c:5281
do_read_fault mm/memory.c:5716 [inline]
do_fault mm/memory.c:5850 [inline]
do_pte_missing mm/memory.c:4362 [inline]
handle_pte_fault mm/memory.c:6195 [inline]
__handle_mm_fault mm/memory.c:6336 [inline]
handle_mm_fault+0xf78/0x2be0 mm/memory.c:6505
faultin_page mm/gup.c:1126 [inline]
__get_user_pages+0x102a/0x1ed0 mm/gup.c:1428
populate_vma_page_range mm/gup.c:1860 [inline]
__mm_populate+0x243/0x3a0 mm/gup.c:1963
mm_populate include/linux/mm.h:3478 [inline]
vm_mmap_pgoff+0x232/0x2e0 mm/util.c:586
ksys_mmap_pgoff+0x268/0x310 mm/mmap.c:604
x64_sys_call+0x14a3/0x3000 arch/x86/include/generated/asm/syscalls_64.h:10
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read-write to 0xffff888117725760 of 4 bytes by task 6139 on cpu 1:
shrink_readahead_size_eio mm/filemap.c:2386 [inline]
filemap_read_folio+0xea/0x110 mm/filemap.c:2456
filemap_fault+0x58f/0xb60 mm/filemap.c:3581
__do_fault+0xbc/0x200 mm/memory.c:5281
do_read_fault mm/memory.c:5716 [inline]
do_fault mm/memory.c:5850 [inline]
do_pte_missing mm/memory.c:4362 [inline]
handle_pte_fault mm/memory.c:6195 [inline]
__handle_mm_fault mm/memory.c:6336 [inline]
handle_mm_fault+0xf78/0x2be0 mm/memory.c:6505
do_user_addr_fault+0x3fe/0x1080 arch/x86/mm/fault.c:1387
handle_page_fault arch/x86/mm/fault.c:1476 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
fault_in_readable+0xad/0x170 mm/gup.c:-1
fault_in_iov_iter_readable+0x129/0x210 lib/iov_iter.c:94
generic_perform_write+0x3cf/0x490 mm/filemap.c:4304
__generic_file_write_iter+0x9e/0x120 mm/filemap.c:4372
generic_file_write_iter+0x8d/0x2f0 mm/filemap.c:4398
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x52a/0x960 fs/read_write.c:686
ksys_write+0xda/0x1a0 fs/read_write.c:738
__do_sys_write fs/read_write.c:749 [inline]
__se_sys_write fs/read_write.c:746 [inline]
__x64_sys_write+0x40/0x50 fs/read_write.c:746
x64_sys_call+0x2802/0x3000 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000020 -> 0x00000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6139 Comm: syz.3.869 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================


---
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 syzk...@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