[moderation] [fs?] KCSAN: data-race in filemap_read / filemap_read (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b401b621758e Linux 6.8-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=100175d0180000
kernel config: https://syzkaller.appspot.com/x/.config?x=7507056e4ee79a
dashboard link: https://syzkaller.appspot.com/bug?extid=09dfcf3eef369d2f098c
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/292988b16d14/disk-b401b621.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/87ac90addfde/vmlinux-b401b621.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f1b26db595a7/bzImage-b401b621.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+09dfcf...@syzkaller.appspotmail.com

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

read to 0xffff88813929e890 of 8 bytes by task 8733 on cpu 1:
filemap_read+0x89/0x680 mm/filemap.c:2570
generic_file_read_iter+0x78/0x330 mm/filemap.c:2784
ext4_file_read_iter+0x1d8/0x2a0
call_read_iter include/linux/fs.h:2079 [inline]
copy_splice_read+0x39f/0x5d0 fs/splice.c:365
do_splice_read fs/splice.c:984 [inline]
splice_direct_to_actor+0x288/0x660 fs/splice.c:1089
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x3b9/0x960 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff88813929e890 of 8 bytes by task 8746 on cpu 0:
filemap_read+0x60b/0x680 mm/filemap.c:2672
generic_file_read_iter+0x78/0x330 mm/filemap.c:2784
ext4_file_read_iter+0x1d8/0x2a0
call_read_iter include/linux/fs.h:2079 [inline]
copy_splice_read+0x39f/0x5d0 fs/splice.c:365
do_splice_read fs/splice.c:984 [inline]
splice_direct_to_actor+0x288/0x660 fs/splice.c:1089
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x3b9/0x960 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64 fs/read_write.c:1348 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000000000005a0 -> 0x0000000000000630

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8746 Comm: syz-executor.3 Not tainted 6.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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