[LU-9731] kmods need to be limited to EL minor release kernel

• Type: Bug
• Resolution: Fixed
• Priority: Blocker
• Fix Version/s: Lustre 2.10.1, Lustre 2.11.0
• Affects Version/s: Lustre 2.10.0
• Severity: 3
• Assignee: Brian Murrell (Inactive)
• Reporter: Brian Murrell (Inactive)

Description

Now that kmods are being produced, they need to be limited to the kernel of the RHEL minor release they were created for.

This is because RHEL kernels have a kabi "whitelist".  That means, that only a subset of kernel interfaces are guaranteed to be stable by RHEL's kabi and it's only those interfaces that are put into a kernel's list of "kernel(...) = ..." Provides: and a kmod's Requires:.  This means that a kmod produced for RHEL 7.3 will look compatible with a RHEL 7.4 kernel (because the whitelisted kabi will not have changed across those releases) even though it is not because the Lustre kmods use interfaces that are not on the whitelist and can change from one minor release to another, even though the whitelisted kabi has not changed.

While Red Hat guarantees that these non-whitelisted interfaces will not change within a minor release (i.e. 7.3 to 7.4) there is no such guarantee across minor releases and in practice they probably almost always change across minor releases so a kmod using non-whitelisted interfaces needs to limit itself to the kernel provided in a RHEL minor release.

For a kmod produced on a RHEL 7.3 kernel that means adding a Requires: kernel >= 3.10.0-514, kernel <= 3.10.0-514 to the kmod RPM.

If this is not done, the kmod will install on to a RHEL 7.4 machine, which has an incompatible kernel by default and a compatible kernel (kernel-3.10.0-514*) will not be installed even if it's available in a Yum repo, even though it should be.

Issue Links

• is blocking: LU-9824 kernel update [SLES12 SP2 4.4.74-92.32]
• is related to: LU-11720 SRPM unnecessarily tied to kernel version

Comments

[Gerrit Updater]

John L. Hammond ([e-mail]) merged in patch https://review.whamcloud.com/28438/
Subject: LU-9731 Limit work-around to EL7 only
Project: fs/lustre-release
Branch: b2_10
Current Patch Set:
Commit: 9ea9bc9f870ede585166d32442ba9bd22f653c32

[Gerrit Updater]

Minh Diep ([e-mail]) uploaded a new patch: https://review.whamcloud.com/28438
Subject: LU-9731 Limit work-around to EL7 only
Project: fs/lustre-release
Branch: b2_10
Current Patch Set: 1
Commit: 0c82f83e5ec50507c0ebc586e968abdb7f352c93

[Peter Jones]

Second patch landed for 2.11

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/28202/
Subject: LU-9731 Limit work-around to EL7 only
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 950c511276866efb6af8defe49213fd69b8883d2

[Brian Murrell (Inactive)]

That way the extra Requires would be in all RHEL builds, not just RHEL7

This problem has only been confirmed on EL 7 (so far) so applying it to EL 6 might be inappropriate.

Fencing the fix off into the distro-specific lbuild file might not be horrible though.

[Bob Glossman (Inactive)]

Interesting that the sles12sp2 test run didn't fail to install the client RPMs because of this.

Unless called for in Test-Parameters I don't think any SLES test runs are done routinely. For sure not in review tests.

While I think this additional mod will fix the problem I wonder if it might be more well structured to push the lines putting in extra Requires into a function in lbuild-rhel and then in lbuild call that function if it exists. That way the extra Requires would be in all RHEL builds, not just RHEL7 and would still be left out of non-RHEL builds.

[Gerrit Updater]

Brian J. Murrell ([e-mail]) uploaded a new patch: https://review.whamcloud.com/28202
Subject: LU-9731 Limit work-around to EL7 only
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 83952af84f928fb0289744c61fbe215e56bf32d6

[Brian Murrell (Inactive)]

Interesting that the sles12sp2 test run didn't fail to install the client RPMs because of this.

Given that this patch is specifically to work around a bug in RHEL's kmod building macro, it should probably be limited to RHEL kmod building only.  I'll push a patch for that.

[Bob Glossman (Inactive)]

I think this change mangles the Required strings on SLES. For example in build of current master for sles12sp2 where the kernel version is 4.4.59-92.17 the Requires in the built lustre-client-kmp-default package has:
kernel >= 4.4.59-0
kernel < 4.4.59-1

while the kernel-default for the pristine unpatched upstream kernel has a Provides of:

kernel = 4.4.59-92.17

Don't see how these can properly match for the purposes of install dependencies.

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/28066/
Subject: LU-9731 kmods need to be limited to EL minor release kernel
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 527b2cd8e593b52326519d13418daf34b6b53b0e