[LU-12335] mb_prealloc_table table read/write code is racy

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.13.0
• Severity: 3
• Assignee: Artem Blagodarenko (Inactive)
• Reporter: Artem Blagodarenko (Inactive)

Description

Preallocation table read/write code is racy. There is a  possibility of accessing memory outside of allocated table.
This issue can be easy reproduced. I am not sure, I have to upload test that lead to test system to be crashed. So I put it here.
 
dd if=/dev/zero of=<path_to_ldiskfs_partition> bs=1048576 count=1024 conv=fsync
cat "32 64 128 256" > /proc/fs/ldiskfs/<dev>/prealloc_table

Issue Links

• is related to: LU-12511 Prepare lustre for adoption into the linux kernel
• is related to: LU-12103 Improve block allocation for large partitions