[moderation] [fs?] KCSAN: data-race in filemap_splice_read / generic_file_direct_write (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ab0a97cffa0b Merge tag 'powerpc-6.8-4' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=165f6b9c180000
kernel config: https://syzkaller.appspot.com/x/.config?x=7507056e4ee79a
dashboard link: https://syzkaller.appspot.com/bug?extid=f17c46e8d1aa26039602
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/786f1e630b29/disk-ab0a97cf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0535b9d0e624/vmlinux-ab0a97cf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2f3bbc61c7ec/bzImage-ab0a97cf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f17c46...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in filemap_splice_read / generic_file_direct_write

write to 0xffff888140f1f168 of 8 bytes by task 27791 on cpu 0:
i_size_write include/linux/fs.h:934 [inline]
generic_file_direct_write+0x19d/0x1f0 mm/filemap.c:3882
__generic_file_write_iter+0xae/0x120 mm/filemap.c:4011
generic_file_write_iter+0x7d/0x1c0 mm/filemap.c:4051
call_write_iter include/linux/fs.h:2087 [inline]
iter_file_splice_write+0x5de/0x950 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x167/0x2c0 fs/splice.c:1164
splice_direct_to_actor+0x2fb/0x660 fs/splice.c:1108
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

read to 0xffff888140f1f168 of 8 bytes by task 27792 on cpu 1:
i_size_read include/linux/fs.h:912 [inline]
filemap_splice_read+0x770/0x8f0 mm/filemap.c:2868
do_splice_read fs/splice.c:985 [inline]
splice_direct_to_actor+0x268/0x660 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: 0x000000000000b600 -> 0x000000000000b800

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27792 Comm: syz-executor.1 Not tainted 6.8.0-rc5-syzkaller-00329-gab0a97cffa0b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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[syzbot]

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