[LU-1665] hsb_head[0] in cfs_hash_bucket_t can experience poor alignment

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.4.0
• Affects Version/s: Lustre 2.2.0, Lustre 2.1.2
• Environment: ia64
• Severity: 3
• Assignee: Keith Mannthey (Inactive)
• Reporter: chas williams - CONTRACTOR

Description

hsb_head[0] can experience poor alignment on certain platforms with odd alignment requirements like the ia64. it is possible for hsb_head[0] to be aligned to a 32-bit boundary, but later it could be cast to something with a stricter alignment requirement. this can/does cause hardware faults for unaligned access:

Jul 18 19:25:20 seraph kernel: kernel unaligned access to 0xe0000069eef8f194, ip=0xa00000028342e0d1
Jul 18 19:25:20 seraph kernel: kernel unaligned access to 0xe0000069eef8f19c, ip=0xa00000028342e0d1
Jul 18 19:25:20 seraph kernel: kernel unaligned access to 0xe0000069eef8f1a4, ip=0xa00000028342e0d1
Jul 18 19:25:20 seraph kernel: kernel unaligned access to 0xe0000069eef8f1ac, ip=0xa00000028342e0d1
Jul 18 19:25:20 seraph kernel: kernel unaligned access to 0xe0000069eef8f1b4, ip=0xa00000028342e0d1