[moderation] [mm?] KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7b63ef2d55f2 Merge tag 'for-7.3-rc6-tag' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13cb6ed1580000
kernel config: https://syzkaller.appspot.com/x/.config?x=de3702ecab64292d
dashboard link: https://syzkaller.appspot.com/bug?extid=18a47cfd5595accbfbc0
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
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/266173db5ae6/disk-7b63ef2d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/86f2268ce34f/vmlinux-7b63ef2d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7a7b0b79e02f/bzImage-7b63ef2d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+18a47c...@syzkaller.appspotmail.com

loop7: detected capacity change from 0 to 512
EXT4-fs (loop7): encrypted files will use data=ordered instead of data journaling mode
EXT4-fs (loop7): 1 truncate cleaned up
==================================================================
BUG: KCSAN: data-race in do_sync_mmap_readahead / do_sync_mmap_readahead

write to 0xffff88812937bbc8 of 8 bytes by task 11057 on cpu 1:
do_sync_mmap_readahead+0x329/0x380 mm/filemap.c:3435
filemap_fault+0x369/0xb60 mm/filemap.c:3597
__do_fault mm/memory.c:5565 [inline]
do_read_fault mm/memory.c:6000 [inline]
do_fault mm/memory.c:6134 [inline]
do_pte_missing mm/memory.c:4700 [inline]
handle_pte_fault mm/memory.c:6558 [inline]
__handle_mm_fault mm/memory.c:6707 [inline]
handle_mm_fault+0x2310/0x3bb0 mm/memory.c:6876
faultin_page mm/gup.c:1126 [inline]
__get_user_pages+0x12e9/0x1eb0 mm/gup.c:1428
populate_vma_page_range mm/gup.c:1860 [inline]
__mm_populate+0x242/0x390 mm/gup.c:1963
mm_populate include/linux/mm.h:4288 [inline]
vm_mmap_pgoff+0x23b/0x2d0 mm/util.c:586
ksys_mmap_pgoff+0x250/0x310 mm/mmap.c:619
x64_sys_call+0x23b3/0x2550 arch/x86/include/generated/asm/syscalls_64.h:10
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 0xffff88812937bbc8 of 8 bytes by task 11052 on cpu 0:
do_sync_mmap_readahead+0x2a3/0x380 mm/filemap.c:3442
filemap_fault+0x369/0xb60 mm/filemap.c:3597
__do_fault mm/memory.c:5565 [inline]
do_shared_fault mm/memory.c:6064 [inline]
do_fault mm/memory.c:6138 [inline]
do_pte_missing mm/memory.c:4700 [inline]
handle_pte_fault mm/memory.c:6558 [inline]
__handle_mm_fault mm/memory.c:6707 [inline]
handle_mm_fault+0x2672/0x3bb0 mm/memory.c:6876
do_user_addr_fault+0x404/0x1060 arch/x86/mm/fault.c:1394
handle_page_fault arch/x86/mm/fault.c:1483 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1536
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
__put_user_4+0xd/0x30 arch/x86/lib/putuser.S:92
__sys_sendmmsg+0x1a8/0x320 net/socket.c:2861
__do_sys_sendmmsg net/socket.c:2883 [inline]
__se_sys_sendmmsg net/socket.c:2880 [inline]
__x64_sys_sendmmsg+0x57/0x70 net/socket.c:2880
x64_sys_call+0x1fb4/0x2550 arch/x86/include/generated/asm/syscalls_64.h:308
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: 0x0000000000000006 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 11052 Comm: syz.7.1672 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================


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