KCSAN: data-race in __ext4_new_inode / _find_next

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __ext4_new_inode / _find_next_bit ext4				118	1134d	1330d	0/28	auto-closed as invalid on 2022/01/24 22:12

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BUG: KCSAN: data-race in __ext4_new_inode / _find_next_bit

read-write to 0xffff88823ff240a8 of 8 bytes by task 10254 on cpu 1:
 instrument_read_write include/linux/instrumented.h:57 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:81 [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:56 [inline]
 __ext4_new_inode+0xf49/0x2700 fs/ext4/ialloc.c:1097
 ext4_symlink+0x2ba/0x6f0 fs/ext4/namei.c:3293
 vfs_symlink+0x18a/0x280 fs/namei.c:4297
 do_symlinkat+0xe2/0x330 fs/namei.c:4326
 __do_sys_symlinkat fs/namei.c:4343 [inline]
 __se_sys_symlinkat fs/namei.c:4340 [inline]
 __x64_sys_symlinkat+0x5e/0x70 fs/namei.c:4340
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88823ff240a8 of 8 bytes by task 10257 on cpu 0:
 _find_next_bit+0xe0/0x190 lib/find_bit.c:60
 find_next_zero_bit include/linux/find.h:102 [inline]
 find_next_zero_bit_le include/linux/find.h:218 [inline]
 find_inode_bit+0xc8/0x330 fs/ext4/ialloc.c:725
 __ext4_new_inode+0xc82/0x2700 fs/ext4/ialloc.c:1066
 ext4_symlink+0x2ba/0x6f0 fs/ext4/namei.c:3293
 vfs_symlink+0x18a/0x280 fs/namei.c:4297
 do_symlinkat+0xe2/0x330 fs/namei.c:4326
 __do_sys_symlinkat fs/namei.c:4343 [inline]
 __se_sys_symlinkat fs/namei.c:4340 [inline]
 __x64_sys_symlinkat+0x5e/0x70 fs/namei.c:4340
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000000 -> 0x0000000000000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10257 Comm: syz-executor.0 Not tainted 5.18.0-rc6-syzkaller-00007-g9be9ed2612b5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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