[moderation] [mm?] KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9dd1835ecda5 Merge tag 'dma-mapping-6.17-2025-09-09' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113af87c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd
dashboard link: https://syzkaller.appspot.com/bug?extid=bfcd49223b48fbfc8e5f
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [ak...@linux-foundation.org da...@redhat.com 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/bed60878f1bb/disk-9dd1835e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7a737ddc0fed/vmlinux-9dd1835e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/39c2c269c318/bzImage-9dd1835e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bfcd49...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead

write to 0xffff8881040f7150 of 8 bytes by task 20334 on cpu 0:
do_sync_mmap_readahead+0x2ba/0x320 mm/filemap.c:-1
filemap_fault+0x313/0xb40 mm/filemap.c:3445
__do_fault+0xb9/0x200 mm/memory.c:5152
do_read_fault mm/memory.c:5573 [inline]
do_fault mm/memory.c:5707 [inline]
do_pte_missing mm/memory.c:4234 [inline]
handle_pte_fault mm/memory.c:6052 [inline]
__handle_mm_fault mm/memory.c:6195 [inline]
handle_mm_fault+0xf78/0x2c20 mm/memory.c:6364
faultin_page mm/gup.c:1144 [inline]
__get_user_pages+0x102e/0x1fa0 mm/gup.c:1446
__get_user_pages_locked mm/gup.c:1712 [inline]
get_dump_page+0xb5/0x250 mm/gup.c:2212
dump_user_range+0x145/0x8f0 fs/coredump.c:1364
elf_core_dump+0x1e00/0x1f90 fs/binfmt_elf.c:2085
coredump_write+0xb0a/0xe30 fs/coredump.c:1049
vfs_coredump+0x142f/0x20c0 fs/coredump.c:1168
get_signal+0xd85/0xf70 kernel/signal.c:3019
arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
irqentry_exit_to_user_mode+0x5e/0xa0 kernel/entry/common.c:73
irqentry_exit+0x12/0x50 kernel/entry/common.c:177
exc_general_protection+0x15b/0x1f0 arch/x86/kernel/traps.c:792
asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617

read to 0xffff8881040f7150 of 8 bytes by task 20315 on cpu 1:
do_sync_mmap_readahead+0x2fc/0x320 mm/filemap.c:3303
filemap_fault+0x313/0xb40 mm/filemap.c:3445
__do_fault+0xb9/0x200 mm/memory.c:5152
do_read_fault mm/memory.c:5573 [inline]
do_fault mm/memory.c:5707 [inline]
do_pte_missing mm/memory.c:4234 [inline]
handle_pte_fault mm/memory.c:6052 [inline]
__handle_mm_fault mm/memory.c:6195 [inline]
handle_mm_fault+0xf78/0x2c20 mm/memory.c:6364
faultin_page mm/gup.c:1144 [inline]
__get_user_pages+0x102e/0x1fa0 mm/gup.c:1446
__get_user_pages_locked mm/gup.c:1712 [inline]
get_dump_page+0xb5/0x250 mm/gup.c:2212
dump_user_range+0x145/0x8f0 fs/coredump.c:1364
elf_core_dump+0x1e00/0x1f90 fs/binfmt_elf.c:2085
coredump_write+0xb0a/0xe30 fs/coredump.c:1049
vfs_coredump+0x142f/0x20c0 fs/coredump.c:1168
get_signal+0xd85/0xf70 kernel/signal.c:3019
arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
irqentry_exit_to_user_mode+0x5e/0xa0 kernel/entry/common.c:73
irqentry_exit+0x12/0x50 kernel/entry/common.c:177
exc_general_protection+0x15b/0x1f0 arch/x86/kernel/traps.c:792
asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:617

value changed: 0x0000000000000f0f -> 0x0000000000000687

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 20315 Comm: syz.4.5981 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


---
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