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To:     linux-kernel@vger.kernel.org
From:   Akemi Yagi <toracat@elrepo.org>
Subject: Re: [PATCH 0/2] pipe: Fixes [ver #2]
Date:   Sat, 7 Dec 2019 13:31:13 -0800
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On 12/6/19 10:59 AM, Linus Torvalds wrote:
> Hmm. I think I just saw this same bug with a plain kernel compile.
> 
> My "make -j32" suddenly came to a crawl, and seems to be entirely
> single-threaded.
> 
> And that's almost certainly because the way 'make' handles load
> distribution is with a network of pipes that has a token passed to the
> sub-makes.
> 
> So there's most definitely something wrong with the new pipe rework.
> Well, I can't _guarantee_ the pipes are the cause of this, but it does
> smell like it.
> 
>                Linus
> 

We encountered what seems to be the same problem when building a kernel
under RHEL 8.

As it turned out, this was due to a bug in make (make-4.2.1-9.el8) and
a patch is available. Details are found in this Red Hat bugzilla report:

https://bugzilla.redhat.com/show_bug.cgi?id=1774790

Akemi