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Message-Id: <20220619104228.A9789201F7@orac.inputplus.co.uk>
Date: Sun, 19 Jun 2022 11:42:28 +0100
From: Ralph Corderoy <ralph@...utplus.co.uk>
To: Matthew Wilcox <willy@...radead.org>
cc: Nate Karstens <nate.karstens@...min.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
Jeff Layton <jlayton@...nel.org>,
"J. Bruce Fields" <bfields@...ldses.org>,
Arnd Bergmann <arnd@...db.de>,
Richard Henderson <rth@...ddle.net>,
Ivan Kokshaysky <ink@...assic.park.msu.ru>,
Matt Turner <mattst88@...il.com>,
"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
Helge Deller <deller@....de>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
David Laight <David.Laight@...lab.com>,
linux-fsdevel@...r.kernel.org, linux-arch@...r.kernel.org,
linux-alpha@...r.kernel.org, linux-parisc@...r.kernel.org,
sparclinux@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, Changli Gao <xiaosuo@...il.com>
Subject: Re: [PATCH v2] Implement close-on-fork
Hi Matthew, thanks for replying.
> > The need for O_CLOFORK might be made more clear by looking at a
> > long-standing Go issue, i.e. unrelated to system(3), which was started
> > in 2017 by Russ Cox when he summed up the current race-condition
> > behaviour of trying to execve(2) a newly created file:
> > https://github.com/golang/go/issues/22315.
>
> The problem is that people advocating for O_CLOFORK understand its
> value, but not its cost. Other google employees have a system which
> has literally millions of file descriptors in a single process.
> Having to maintain this extra state per-fd is a cost they don't want
> to pay (and have been quite vocal about earlier in this thread).
So do you agree the userspace issue is best solved by *_CLOFORK and the
problem is how to implement *_CLOFORK at an acceptable cost?
OTOH David Laight was making suggestions on moving the load to the
fork/exec path earlier in the thread, but OTOH Al Viro mentioned a
‘portable solution’, though that could have been to a specific issue
rather than the more general case.
How would you recommend approaching an acceptable cost is progressed?
Iterate on patch versions? Open a bugzilla.kernel.org for central
tracking and linking from the other projects? ..?
--
Cheers, Ralph.
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