KCSAN: data-race in ext4_setattr / generic_file_buffered_read (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c84e1efa Merge tag 'asm-generic-fixes-5.10-2' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1393c3dd500000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9b19d1bde60f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=d3272ea1c7536cf44408
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
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.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d3272e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in ext4_setattr / generic_file_buffered_read

write to 0xffff888009652c50 of 8 bytes by task 15301 on cpu 1:
i_size_write include/linux/fs.h:871 [inline]
ext4_setattr+0xe27/0xf70 fs/ext4/inode.c:5470
notify_change+0x7b3/0xa50 fs/attr.c:336
do_truncate fs/open.c:64 [inline]
do_sys_ftruncate+0x42d/0x530 fs/open.c:195
__do_sys_ftruncate fs/open.c:205 [inline]
__se_sys_ftruncate fs/open.c:203 [inline]
__x64_sys_ftruncate+0x2f/0x40 fs/open.c:203
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888009652c50 of 8 bytes by task 15289 on cpu 0:
i_size_read include/linux/fs.h:849 [inline]
generic_file_buffered_read+0x1426/0x23a0 mm/filemap.c:2302
generic_file_read_iter+0x80/0x3d0 mm/filemap.c:2553
ext4_file_read_iter+0x2d0/0x420 fs/ext4/file.c:74
call_read_iter include/linux/fs.h:1897 [inline]
generic_file_splice_read+0x22a/0x310 fs/splice.c:311
do_splice_to fs/splice.c:788 [inline]
splice_direct_to_actor+0x2aa/0x650 fs/splice.c:867
do_splice_direct+0xf5/0x170 fs/splice.c:976
do_sendfile+0x5db/0xca0 fs/read_write.c:1257
__do_sys_sendfile64 fs/read_write.c:1312 [inline]
__se_sys_sendfile64 fs/read_write.c:1304 [inline]
__x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1304
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15289 Comm: syz-executor.0 Not tainted 5.10.0-rc5-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.