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BUG: KCSAN: data-race in find_group_orlov / percpu_counter_add_batch

write to 0xffff8882181de8e0 of 8 bytes by task 8711 on cpu 0:
 percpu_counter_add_batch+0xca/0x150 lib/percpu_counter.c:91
 percpu_counter_add include/linux/percpu_counter.h:55 [inline]
 ext4_free_blocks+0xb44/0x1810 fs/ext4/mballoc.c:4928
 ext4_remove_blocks fs/ext4/extents.c:2684 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2850 [inline]
 ext4_ext_remove_space+0x1828/0x3750 fs/ext4/extents.c:3097
 ext4_ext_truncate+0x120/0x130 fs/ext4/extents.c:4620
 ext4_truncate+0x5c8/0x9d0 fs/ext4/inode.c:4175
 ext4_setattr+0xdda/0x1670 fs/ext4/inode.c:5333
 notify_change+0x7e1/0xaa0 fs/attr.c:337
 do_truncate+0xfb/0x180 fs/open.c:64
 handle_truncate fs/namei.c:3015 [inline]
 do_last fs/namei.c:3426 [inline]
 path_openat+0x13e8/0x3580 fs/namei.c:3537
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 ksys_open include/linux/syscalls.h:1385 [inline]
 __do_sys_creat fs/open.c:1155 [inline]
 __se_sys_creat fs/open.c:1153 [inline]
 __x64_sys_creat+0x45/0x60 fs/open.c:1153
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8882181de8e0 of 8 bytes by task 7713 on cpu 1:
 find_group_orlov+0x15c/0x8d0 fs/ext4/ialloc.c:438
 __ext4_new_inode+0xaea/0x2f10 fs/ext4/ialloc.c:866
 ext4_mkdir+0x270/0x820 fs/ext4/namei.c:2774
 vfs_mkdir+0x283/0x390 fs/namei.c:3819
 do_mkdirat+0x1ac/0x1f0 fs/namei.c:3842
 __do_sys_mkdir fs/namei.c:3858 [inline]
 __se_sys_mkdir fs/namei.c:3856 [inline]
 __x64_sys_mkdir+0x40/0x50 fs/namei.c:3856
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7713 Comm: syz-executor.5 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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