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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 6 Dec 2019 13:04:01 -0800
Message-ID: <CAHk-=wjvO1V912ya=1rdXwrm1OBTi6GqnqryH_E8OR69cZuVOg@mail.gmail.com>
Subject: Re: [PATCH 0/2] pipe: Fixes [ver #2]
To:     David Sterba <dsterba@suse.cz>,
        David Howells <dhowells@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Eric Biggers <ebiggers@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Dec 6, 2019 at 12:28 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I think I found it.
>
> TOTALLY UNTESTED patch appended. It's whitespace-damaged and may be
> completely wrong. And might not fix it.

Well, it compiles, and it's obviously correct, so I've committed it.

It doesn't fix my "kernel compiles go single-threaded" issue. Which is
not surprising - make doesn't use splice(), it just reads and writes
single characters (the main make server writes a "+" character for
each available job, and parallel sub-makes will read one for each job
they start and write one when done - or something very close to that).

I think that is related to the other pipe changes, though - there were
some wakeup changes in there too. The btrfs problem was bisected to
the original commit, which is what I think my patch fixes.

                  Linus