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Date: Mon, 26 May 2014 15:35:12 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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To: Jeff Smith <jsmith.lkml@gmail.com>,
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CC: Christoph Hellwig <hch@infradead.org>,
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        Peter Zijlstra <peterz@infradead.org>, Dave Jones <davej@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: remap_file_pages() use
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Il 26/05/2014 15:24, Jeff Smith ha scritto:
> Your addr2 mmap() call is a bit incorrect semantically and
> syntactically (you skipped the length arg). The addr2 request will
> fail because mmap() does not implicitly munmap() occupied virtual
> address space.

With MAP_FIXED it does.  It is in the man page.

Paolo

> Even if you did that, the following still has a race
> condition between the addr2 request and another thread grabbing the
> same virtual space, which nothing short of a lock on all threads'
> mmap()-ing logic can protect: