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How we spent two weeks hunting an NFS bug in the Linux kernel

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Re: How we spent two weeks hunting an NFS bug in the Linux kernel

#2
I spend my days chasing bugs like this in the FreeBSD kernel, and make heavy use of dtrace. I expect that using something like bpftrace(1) might have accelerated their debugging as compared to inserting stack traces and prints...

(1): http://www.brendangregg.com/blog/2018-10-08/dtrace-for-linux...

Re: How we spent two weeks hunting an NFS bug in the Linux kernel

#4
post #2

I spend my days chasing bugs like this in the FreeBSD kernel, and make heavy use of dtrace. I expect that using something like bpftrace(1) might have accelerated their debugging as compared to inserting stack traces and prints... (1): http://www.brendangregg.com/blog/2018-10-08/dtrace-for-linux...

Out of curiosity, what do you do that you get to do that? Sounds fascinating---I've had lots of fun with dtrace (and, more recently, bcc).

Re: How we spent two weeks hunting an NFS bug in the Linux kernel

#6

Excellent write-up, I like how they briefly summarized each section so you knew what to expect (I find it helps with understanding). Including the false path is very nice as well since those are very common when debugging.

Completely agree, finding and fixing the bug is commendable enough. But being so thorough as to provide a free educational lesson to everyone else about professional debugging is the kind of self-promotional material I definitely want to read.

Re: How we spent two weeks hunting an NFS bug in the Linux kernel

#7
Great post! In my own experience of working with NFS version 4 servers, we discovered several bugs that have been actually fixed in latest version of kernels. The unfortunate thing is that most enterprises still run old CentOS / Redhat release kernels that although are stable, but yet lack several of these fixes.

Re: How we spent two weeks hunting an NFS bug in the Linux kernel

#10
post #7

Great post! In my own experience of working with NFS version 4 servers, we discovered several bugs that have been actually fixed in latest version of kernels. The unfortunate thing is that most enterprises still run old CentOS / Redhat release kernels that although are stable, but yet lack several of these fixes.

Red Hat usually backports those sorts of fixes to their old-looking kernel versions.
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