KCSAN: data-race in ext4_mb_find_by_goal / mb_free_blocks (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: eccc8767 Merge branch 'fixes' of git://git.kernel.org/pub/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=174f3684500000
kernel config: https://syzkaller.appspot.com/x/.config?x=671e27f23e60a67b
dashboard link: https://syzkaller.appspot.com/bug?extid=a6f7ed7ba66ef98fddda
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+a6f7ed...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in ext4_mb_find_by_goal / mb_free_blocks

read-write to 0xffff8881417181c4 of 4 bytes by task 8479 on cpu 0:
mb_free_blocks+0x13d/0xe00 fs/ext4/mballoc.c:1486
ext4_free_blocks+0x13b2/0x1c80 fs/ext4/mballoc.c:5470
ext4_remove_blocks+0x7d5/0x9e0 fs/ext4/extents.c:2498
ext4_ext_rm_leaf+0x69e/0xe60 fs/ext4/extents.c:2664
ext4_ext_remove_space+0x936/0x13e0 fs/ext4/extents.c:2912
ext4_ext_truncate+0xf9/0x160 fs/ext4/extents.c:4370
ext4_truncate+0x82b/0xbb0 fs/ext4/inode.c:4254
ext4_evict_inode+0x938/0xc00 fs/ext4/inode.c:280
evict+0x19f/0x470 fs/inode.c:578
iput_final fs/inode.c:1654 [inline]
iput+0x421/0x510 fs/inode.c:1680
do_unlinkat+0x2c9/0x4d0 fs/namei.c:3903
__do_sys_unlink fs/namei.c:3943 [inline]
__se_sys_unlink fs/namei.c:3941 [inline]
__x64_sys_unlink+0x2c/0x30 fs/namei.c:3941
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881417181c4 of 4 bytes by task 685 on cpu 1:
ext4_mb_find_by_goal+0x129/0xb30 fs/ext4/mballoc.c:1889
ext4_mb_regular_allocator+0x10f/0x18a0 fs/ext4/mballoc.c:2320
ext4_mb_new_blocks+0x6e8/0x1140 fs/ext4/mballoc.c:4997
ext4_ext_map_blocks+0x15a0/0x1fc0 fs/ext4/extents.c:4238
ext4_map_blocks+0x700/0xfc0 fs/ext4/inode.c:628
ext4_alloc_file_blocks+0x26f/0x700 fs/ext4/extents.c:4426
ext4_fallocate+0x2a7/0x540 fs/ext4/extents.c:4705
vfs_fallocate+0x43d/0x5d0 fs/open.c:309
file_ioctl fs/ioctl.c:494 [inline]
do_vfs_ioctl+0xdc9/0xec0 fs/ioctl.c:732
__do_sys_ioctl fs/ioctl.c:751 [inline]
__se_sys_ioctl+0x83/0x140 fs/ioctl.c:739
__x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
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: 685 Comm: syz-executor.5 Not tainted 5.10.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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