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BUG: KCSAN: data-race in __ext4_new_inode / find_next_zero_bit

write to 0xffff88810511f300 of 8 bytes by task 10900 on cpu 1:
 instrument_write include/linux/instrumented.h:42 [inline]
 __set_bit include/asm-generic/bitops/instrumented-non-atomic.h:27 [inline]
 __set_bit_le include/asm-generic/bitops/le.h:70 [inline]
 __ext4_new_inode+0xfb1/0x2f10 fs/ext4/ialloc.c:1100
 ext4_symlink+0x2c3/0x700 fs/ext4/namei.c:3347
 vfs_symlink+0x23a/0x300 fs/namei.c:4172
 do_symlinkat+0xeb/0x280 fs/namei.c:4202
 __do_sys_symlink fs/namei.c:4223 [inline]
 __se_sys_symlink fs/namei.c:4221 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4221
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810511f300 of 8 bytes by task 10899 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_symlink+0x2c3/0x700 fs/ext4/namei.c:3347
 vfs_symlink+0x23a/0x300 fs/namei.c:4172
 do_symlinkat+0xeb/0x280 fs/namei.c:4202
 __do_sys_symlink fs/namei.c:4223 [inline]
 __se_sys_symlink fs/namei.c:4221 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4221
 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: 10899 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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