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BUG: KCSAN: data-race in __ext4_new_inode / find_next_zero_bit

write to 0xffff88812361b010 of 8 bytes by task 16768 on cpu 0:
 __test_and_set_bit include/asm-generic/bitops-instrumented.h:168 [inline]
 __test_and_set_bit_le include/asm-generic/bitops/le.h:90 [inline]
 __ext4_new_inode+0xf54/0x3070 fs/ext4/ialloc.c:944
 ext4_symlink+0x30e/0x970 fs/ext4/namei.c:3262
 vfs_symlink fs/namei.c:4119 [inline]
 vfs_symlink+0x218/0x310 fs/namei.c:4105
 do_symlinkat+0x1a5/0x1e0 fs/namei.c:4146
 __do_sys_symlink fs/namei.c:4165 [inline]
 __se_sys_symlink fs/namei.c:4163 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4163
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812361b010 of 8 bytes by task 16770 on cpu 1:
 _find_next_bit lib/find_bit.c:39 [inline]
 find_next_zero_bit+0x4e/0xe0 lib/find_bit.c:79
 find_next_zero_bit_le include/asm-generic/bitops/le.h:15 [inline]
 find_inode_bit.isra.0+0x82/0x300 fs/ext4/ialloc.c:715
 __ext4_new_inode+0xd4b/0x3070 fs/ext4/ialloc.c:914
 ext4_create+0x152/0x370 fs/ext4/namei.c:2587
 lookup_open fs/namei.c:3224 [inline]
 do_last fs/namei.c:3314 [inline]
 path_openat+0x2b4d/0x36e0 fs/namei.c:3525
 do_filp_open+0x11e/0x1b0 fs/namei.c:3555
 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/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 16770 Comm: syz-executor.4 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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