KCSAN: data-race in __add_to_page_cache_locked / ext4_writepages (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aae5ab85 Merge tag 'riscv-for-linus-5.10-rc6' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=101c9553500000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9b19d1bde60f8d
dashboard link: https://syzkaller.appspot.com/bug?extid=2c1b4e6c6c4369be36fd
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org]

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+2c1b4e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __add_to_page_cache_locked / ext4_writepages

read-write to 0xffff88800a4e9358 of 8 bytes by task 23059 on cpu 0:
__add_to_page_cache_locked+0x39d/0x7b0 mm/filemap.c:888
add_to_page_cache_lru+0xa0/0x1b0 mm/filemap.c:939
generic_file_buffered_read+0xf29/0x23a0 mm/filemap.c:2455
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:1318 [inline]
__se_sys_sendfile64 fs/read_write.c:1304 [inline]
__x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88800a4e9358 of 8 bytes by task 23066 on cpu 1:
ext4_writepages+0x131/0x1e30 fs/ext4/inode.c:2660
do_writepages+0x7b/0x150 mm/page-writeback.c:2352
__filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
filemap_write_and_wait_range+0x8b/0x2a0 mm/filemap.c:655
__iomap_dio_rw+0x38c/0x9b0 fs/iomap/direct-io.c:489
iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:605
ext4_dio_write_iter fs/ext4/file.c:552 [inline]
ext4_file_write_iter+0xe06/0x1090 fs/ext4/file.c:662
call_write_iter include/linux/fs.h:1903 [inline]
do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
do_iter_write+0x112/0x4b0 fs/read_write.c:866
vfs_iter_write+0x4c/0x70 fs/read_write.c:907
iter_file_splice_write+0x42a/0x780 fs/splice.c:686
do_splice_from fs/splice.c:764 [inline]
direct_splice_actor+0x80/0xa0 fs/splice.c:933
splice_direct_to_actor+0x345/0x650 fs/splice.c:888
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:1318 [inline]
__se_sys_sendfile64 fs/read_write.c:1304 [inline]
__x64_sys_sendfile64+0xf2/0x130 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: 1 PID: 23066 Comm: syz-executor.1 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.