[Bug 1681909] Re: kdump is not captured in remote host when kdump over ssh is configured

[Eric Desrochers]

Quick update

# excuses... page:

makedumpfile (1:1.6.5-1ubuntu2 to 1:1.6.5-1ubuntu3)
Maintainer: Louis Bouchard
0 days old
autopkgtest for kpatch/0.5.0-0ubuntu2: amd64: Ignored failure
autopkgtest for makedumpfile/1:1.6.5-1ubuntu3: amd64: Pass, arm64: Pass, armhf: Pass, i386: Pass, ppc64el: Regression ♻ , s390x: Ignored failure
Not considered

# logs
.....
makedumpfile: crash test: checking for crash file
makedumpfile: ERROR: crash test: Found no compressed dumps
.....

gpicolli and I are investigating the root cause.

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https://bugs.launchpad.net/bugs/1681909

Title:
  kdump is not captured in remote host when kdump over ssh is configured

Status in The Ubuntu-power-systems project:
  In Progress
Status in makedumpfile package in Ubuntu:
  Fix Committed
Status in makedumpfile source package in Xenial:
  Won't Fix
Status in makedumpfile source package in Bionic:
  In Progress
Status in makedumpfile source package in Cosmic:
  Won't Fix
Status in makedumpfile source package in Disco:
  In Progress
Status in makedumpfile source package in Eoan:
  Fix Committed

Bug description:
  [Impact]

  * Kdump over network (like NFS mount or SSH dump) relies on network-
  online target from systemd. Even so, there are some NICs that report
  "Link Up" state but aren't ready to transmit packets. This is a
  generally bad behavior that is credited probably to NIC firmware
  delays, usually not fixable from drivers. Some adapters known to act
  like this are bnx2x, tg3 and ixgbe.

  * Kdump is a mechanism that may be a last resort to debug complex/hard
  to reproduce issues, so it's interesting to increase its reliability /
  resilience. We then propose here a solution/quirk to this issue on
  network dump by adding a retry/delay mechanism; if it's a network
  dump, kdump will retry some times and sleep between the attempts in
  order to exclude the case of NICs that aren't ready yet but will soon
  be able to transmit packets.

  * Although first reported by IBM in PowerPC arch, the scope for this
  issue is the NIC, and it was later reported in x86 arch too.

  [Test case]

  Usually it's difficult to naturally reproduce this issue in a deterministic way, but we have an artificial test case on comment #24 of this LP.
  Also, we have a report from this bug in which the user managed to reproduce the problem consistently - it's fixed after testing our solution.

  [Regression potential]

  There's not a clear regression potential here since it's just a retry/delay mechanism. Some potential problems may come from bad coding in the script.
  The delay between attempts is only 3 sec per iteration, so it shouldn't block the kdump progress for a high amount of time at once.

  [Other information]

  Salsa Debian commit:
  https://salsa.debian.org/debian/makedumpfile/commit/d63ba95337988be1eac8c8c76d90825ff5c6d17f

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