linux-kernel - Re: remap_file

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Message-ID: <53834310.8060808@redhat.com>
Date:	Mon, 26 May 2014 15:35:12 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Jeff Smith <jsmith.lkml@...il.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
CC:	Christoph Hellwig <hch@...radead.org>,
	Kenny Simpson <theonetruekenny@...il.com>,
	Michal Hocko <mhocko@...e.cz>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Dave Jones <davej@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: remap_file_pages() use

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:

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