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References: <20100816.211218.189709876.davem@davemloft.net>
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Date: Tue, 17 Aug 2010 11:24:19 -0700
Message-ID: <AANLkTi=ZdrtWSYE0BEXJ-YDoxjta3h7RMR7Y8Z6Hu-Hc@mail.gmail.com>
Subject: Re: tasks getting stuck on mmap_sem?
From: Tony Luck <tony.luck@intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>, Michel Lespinasse <walken@google.com>,
        David Howells <dhowells@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org
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On Tue, Aug 17, 2010 at 9:14 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> No. Looks like the rwsem changes broke sparc too. ia64 had some problems too.

I did have some similar mmap_sem issues - but the combination of
fixing the types
of the RWSEM_* defines to be unsigned, and the return value of
ia64_atomic64_add()
to be "long" rather than "int" looks to have cleared up the problems I
was seeing. I
could generally see the hung processes in less than 10 consecutive
kernel builds, but
ran a few thousand builds over the weekend with no issues.

If git is multi-threaded, it may be hitting some different code path
... but it isn't trivial
for me to try this out (my systems are on an isolated lab network segment).

-Tony
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