KCSAN: data-race in filemap_read / simple_write_end

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3dbdb38e Merge branch 'for-5.14' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11bc7a80300000
kernel config: https://syzkaller.appspot.com/x/.config?x=2557b67ce612a86c
dashboard link: https://syzkaller.appspot.com/bug?extid=fb24e9f8609a0c1f26f7
compiler: Debian clang version 11.0.1-2
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fb24e9...@syzkaller.appspotmail.com

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

write to 0xffff888106a19280 of 8 bytes by task 8767 on cpu 0:
i_size_write include/linux/fs.h:871 [inline]
simple_write_end+0x293/0x330 fs/libfs.c:591
generic_perform_write+0x23e/0x3a0 mm/filemap.c:3671
__generic_file_write_iter+0x161/0x300 mm/filemap.c:3789
generic_file_write_iter+0x75/0x130 mm/filemap.c:3821
call_write_iter include/linux/fs.h:2114 [inline]
do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
do_iter_write+0x112/0x4c0 fs/read_write.c:866
vfs_iter_write+0x4c/0x70 fs/read_write.c:907
iter_file_splice_write+0x40a/0x750 fs/splice.c:689
do_splice_from fs/splice.c:767 [inline]
direct_splice_actor+0x80/0xa0 fs/splice.c:936
splice_direct_to_actor+0x345/0x650 fs/splice.c:891
do_splice_direct+0xf5/0x170 fs/splice.c:979
do_sendfile+0x773/0xda0 fs/read_write.c:1260
__do_sys_sendfile64 fs/read_write.c:1325 [inline]
__se_sys_sendfile64 fs/read_write.c:1311 [inline]
__x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888106a19280 of 8 bytes by task 8784 on cpu 1:
i_size_read include/linux/fs.h:849 [inline]
filemap_read+0xd68/0x1230 mm/filemap.c:2562
generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2701
call_read_iter include/linux/fs.h:2108 [inline]
generic_file_splice_read+0x22a/0x310 fs/splice.c:311
do_splice_to fs/splice.c:796 [inline]
splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
do_splice_direct+0xf5/0x170 fs/splice.c:979
do_sendfile+0x773/0xda0 fs/read_write.c:1260
__do_sys_sendfile64 fs/read_write.c:1325 [inline]
__se_sys_sendfile64 fs/read_write.c:1311 [inline]
__x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000202fc5 -> 0x0000000000203000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8784 Comm: syz-executor.1 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

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