[LU-10526] Ubuntu Kernel 4.4.0 lacks IB_DEVICE_SG_GAPS_REG and IB_MR_TYPE_SG_GAPS symbols

• Type: Technical task
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.11.0
• Affects Version/s: Lustre 2.10.2
• Environment: Distribution: Ubuntu 14.04/16.04; Kernel: 4.4.0-*

Epic/Theme

lnet

Epic

lnet

• Assignee: WC Triage
• Reporter: Martin Schröder (Inactive)

Description

Recently, a change has been merged to "lnet/klnds/o2iblnd/o2iblnd.c" which introduces the usage of IB_DEVICE_SG_GAPS_REG and IB_MR_TYPE_SG_GAPS.

Unfortunately, these symbols are not available in the 4.4.0 Kernels as used by Ubuntu 14/16.

Additionally, there seems to be general warning against their use:

• https://patchwork.kernel.org/patch/9573483/
• https://lkml.org/lkml/2017/3/13/206

Also, there is a related performance issue as reported in LU-10394.

 

The solution is to create a preprocessor guard around their use, so that Kernels lacking these symbols will not use them and revert to using the older IB_MR_TYPE_MEM_REG, instead.

Issue Links

• is blocking: LU-9564 Support for Lustre Servers on Ubuntu 14.04/16.04 Kernel 4.4.0