Re: [PATCH net] ibmvnic: continue fatal error reset after passive init

On Wed, 23 Dec 2020 14:10:32 -0600 Lijun Pan wrote:

On Wed, Dec 23, 2020 at 10:50 AM Jakub Kicinski [off-list ref] wrote:

quoted

On Wed, 23 Dec 2020 02:21:09 -0600 Lijun Pan wrote:  

quoted

On Tue, Dec 22, 2020 at 8:48 PM Jakub Kicinski [off-list ref] wrote:  

quoted

On Sat, 19 Dec 2020 15:40:34 -0600 Lijun Pan wrote:  

quoted

Commit f9c6cea0b385 ("ibmvnic: Skip fatal error reset after passive init")
says "If the passive
CRQ initialization occurs before the FATAL reset task is processed,
the FATAL error reset task would try to access a CRQ message queue
that was freed, causing an oops. The problem may be most likely to
occur during DLPAR add vNIC with a non-default MTU, because the DLPAR
process will automatically issue a change MTU request.
Fix this by not processing fatal error reset if CRQ is passively
initialized after client-driven CRQ initialization fails."

Even with this commit, we still see similar kernel crashes. In order
to completely solve this problem, we'd better continue the fatal error
reset, capture the kernel crash, and try to fix it from that end.  

This basically reverts the quoted fix. Does the quoted fix make things
worse? Otherwise we should leave the code be until proper fix is found.  

Yes, I think the quoted commit makes things worse. It skips the specific
reset condition, but that does not fix the problem it claims to fix.  

Okay, let's make sure the commit message explains how it makes things
worse.  

I will reword the commit message.

quoted

quoted

The effective fix is upstream SHA 0e435befaea4 and a0faaa27c716. So I
think reverting it to the original "else" condition is the right thing to do.  

Hm. So the problem is fixed? But the commit message says "we still see
similar kernel crashes", that's present tense suggesting that crashes
are seen on current net/master. Are you saying that's not the case and
after 0e435befaea4 and a0faaa27c716 there are no more crashes?  

This patch was formed before I submitted 0e435befaea4 and a0faaa27c716, so
I used the wording "we still see similar kernel crashes". I will modify
the commit message before I submit v2 of this patch.
After 0e435befaea4 and a0faaa27c716, I don't see any crashes as described
in this quoted commit even without this quoted commit.
That's why I am sure this quoted commit does not fix the described problem
and I want to revert it.

I see, that explains it!