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BUG: KCSAN: data-race in ext4_free_inode / find_next_zero_bit

write to 0xffff8881051c6330 of 8 bytes by task 1779 on cpu 1:
 instrument_write include/linux/instrumented.h:42 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:79 [inline]
 __test_and_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:109 [inline]
 __test_and_clear_bit_le include/asm-generic/bitops/le.h:95 [inline]
 ext4_free_inode+0x5ce/0xa00 fs/ext4/ialloc.c:314
 ext4_evict_inode+0xb7e/0xdb0 fs/ext4/inode.c:333
 evict+0x1c8/0x3c0 fs/inode.c:578
 iput_final fs/inode.c:1654 [inline]
 iput+0x433/0x590 fs/inode.c:1680
 do_unlinkat+0x293/0x4f0 fs/namei.c:4105
 __do_sys_unlink fs/namei.c:4145 [inline]
 __se_sys_unlink fs/namei.c:4143 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:4143
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881051c6330 of 8 bytes by task 11917 on cpu 0:
 _find_next_bit lib/find_bit.c:41 [inline]
 find_next_zero_bit+0x3a/0xf0 lib/find_bit.c:89
 find_next_zero_bit_le include/asm-generic/bitops/le.h:15 [inline]
 find_inode_bit+0x30c/0x3a0 fs/ext4/ialloc.c:722
 __ext4_new_inode+0xc6a/0x2f10 fs/ext4/ialloc.c:1063
 ext4_mkdir+0x28a/0x760 fs/ext4/namei.c:2804
 vfs_mkdir+0x135/0x1f0 fs/namei.c:3819
 do_mkdirat+0x11d/0x200 fs/namei.c:3844
 __do_sys_mkdirat fs/namei.c:3857 [inline]
 __se_sys_mkdirat fs/namei.c:3855 [inline]
 __x64_sys_mkdirat+0x3e/0x50 fs/namei.c:3855
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11917 Comm: syz-executor.5 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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