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BUG: KCSAN: data-race in __ext4_new_inode / find_next_zero_bit

write to 0xffff888107cfd310 of 8 bytes by task 14806 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+0xe1b/0x2fe0 fs/ext4/ialloc.c:1093
 ext4_symlink+0x2d1/0x780 fs/ext4/namei.c:3347
 vfs_symlink+0xbe/0x170 fs/namei.c:4178
 do_symlinkat+0x11e/0x2b0 fs/namei.c:4208
 __do_sys_symlink fs/namei.c:4229 [inline]
 __se_sys_symlink fs/namei.c:4227 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4227
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888107cfd310 of 8 bytes by task 14804 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+0xb6c/0x2fe0 fs/ext4/ialloc.c:1063
 ext4_symlink+0x2d1/0x780 fs/ext4/namei.c:3347
 vfs_symlink+0xbe/0x170 fs/namei.c:4178
 do_symlinkat+0x11e/0x2b0 fs/namei.c:4208
 __do_sys_symlink fs/namei.c:4229 [inline]
 __se_sys_symlink fs/namei.c:4227 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4227
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14804 Comm: syz-executor.1 Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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