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BUG: KCSAN: data-race in __ext4_new_inode / find_next_zero_bit

write to 0xffff888104e0d2c0 of 8 bytes by task 1766 on cpu 0:
 instrument_write include/linux/instrumented.h:42 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:79 [inline]
 __test_and_set_bit include/asm-generic/bitops/instrumented-non-atomic.h:95 [inline]
 __test_and_set_bit_le include/asm-generic/bitops/le.h:90 [inline]
 __ext4_new_inode+0xf1e/0x2f10 fs/ext4/ialloc.c:1093
 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_mkdir fs/namei.c:3862 [inline]
 __se_sys_mkdir fs/namei.c:3860 [inline]
 __x64_sys_mkdir+0x32/0x40 fs/namei.c:3860
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888104e0d2c0 of 8 bytes by task 5203 on cpu 1:
 _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_create+0x17c/0x310 fs/ext4/namei.c:2622
 lookup_open fs/namei.c:3221 [inline]
 open_last_lookups fs/namei.c:3291 [inline]
 path_openat+0xcd1/0x20b0 fs/namei.c:3497
 do_filp_open+0xd9/0x1f0 fs/namei.c:3527
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_creat fs/open.c:1277 [inline]
 __se_sys_creat fs/open.c:1271 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1271
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5203 Comm: syz-executor.5 Not tainted 5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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