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From: Kenny Simpson <theonetruekenny@yahoo.com>
To: linux-kernel@vger.kernel.org
Subject: remap_file_pages doesn't like MAP_ANONYMOUS (but used to?)
Date: Wed, 16 Mar 2011 22:54:51 -0700 (PDT)	[thread overview]
Message-ID: <11649.19421.qm@web39421.mail.mud.yahoo.com> (raw)

Hello,
  In older kernels (2.6.15-2.6.18?) I was able to make an anonymous mapping and remap part of it back over itself to create a circular buffer:
  p = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0)
  remap_file_pages(p + sz/2, sz/2, 0/*prot*/, 0/*offset*/, 0/*flags*/)

I find the same method fails with EINVAL on the remap_file_pages call in 2.6.35/38.  Making a dummy file or shared memory object works, but seems a bit more messy.

Why drop support for ANONYMOUS?  Is there another way to get the same effect?

thanks,
-Kenny



      

             reply	other threads:[~2011-03-17  6:01 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-17  5:54 Kenny Simpson [this message]
2011-03-19 22:52 ` Hugh Dickins
2011-03-20 17:51   ` Kenny Simpson
2011-03-21  1:57     ` Hugh Dickins

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