DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
  s=s1024; d=yahoo.com;
  h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding;
  b=V33dYnDEXlFVNLFQgwcNhR/7XLmUPmCgilohnBE8fc1GUhVecVpqVhV9/gfN7ogGDUdVu6y5pNf2732sj7zHnQG2SCCRLehyxIpMw2ep8XDKGjwEekeSfFisGG1ewF5gRRrxgHwd1PqKMgAbDPiFLXVhOvJUjyAfmT//Z7PAwR8=;
Message-ID: <11649.19421.qm@web39421.mail.mud.yahoo.com>
Date: Wed, 16 Mar 2011 22:54:51 -0700 (PDT)
From: Kenny Simpson <theonetruekenny@yahoo.com>
Subject: remap_file_pages doesn't like MAP_ANONYMOUS (but used to?)
To: linux-kernel@vger.kernel.org
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8BIT
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 813
Lines: 20

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


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/