[moderation] [ext4?] KCSAN: data-race in page_cache_sync_ra / page_cache_sync_ra (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7d06015d936c Merge tag 'pci-v6.15-changes' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=111f9198580000
kernel config: https://syzkaller.appspot.com/x/.config?x=475578c269ee9059
dashboard link: https://syzkaller.appspot.com/bug?extid=530a5dab30b6fe76e9a7
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1d10afe62157/disk-7d06015d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e7ed623a76b9/vmlinux-7d06015d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/510b2fa1269d/bzImage-7d06015d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+530a5d...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 2048
==================================================================
BUG: KCSAN: data-race in page_cache_sync_ra / page_cache_sync_ra

write to 0xffff888104492c9c of 4 bytes by task 7938 on cpu 1:
page_cache_sync_ra+0x540/0x680 mm/readahead.c:-1
filemap_get_pages+0x2ba/0x11b0 mm/filemap.c:2602
filemap_splice_read+0x35a/0x930 mm/filemap.c:2992
ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:158
do_splice_read fs/splice.c:979 [inline]
splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0xd9/0x150 fs/splice.c:1227
do_sendfile+0x40a/0x690 fs/read_write.c:1368
__do_sys_sendfile64 fs/read_write.c:1429 [inline]
__se_sys_sendfile64 fs/read_write.c:1415 [inline]
__x64_sys_sendfile64+0x113/0x160 fs/read_write.c:1415
x64_sys_call+0xfc3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104492c9c of 4 bytes by task 7932 on cpu 0:
page_cache_ra_order mm/readahead.c:533 [inline]
page_cache_sync_ra+0x59c/0x680 mm/readahead.c:621
filemap_get_pages+0x2ba/0x11b0 mm/filemap.c:2602
filemap_splice_read+0x35a/0x930 mm/filemap.c:2992
ext4_file_splice_read+0x8f/0xb0 fs/ext4/file.c:158
do_splice_read fs/splice.c:979 [inline]
splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0xd9/0x150 fs/splice.c:1227
do_sendfile+0x40a/0x690 fs/read_write.c:1368
__do_sys_sendfile64 fs/read_write.c:1429 [inline]
__se_sys_sendfile64 fs/read_write.c:1415 [inline]
__x64_sys_sendfile64+0x113/0x160 fs/read_write.c:1415
x64_sys_call+0xfc3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000f -> 0x00000010

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7932 Comm: syz.0.1155 Not tainted 6.14.0-syzkaller-09584-g7d06015d936c #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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[syzbot]

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