From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pizda.ninka.net (pizda.ninka.net [216.101.162.242]) by dsl2.external.hp.com (Postfix) with ESMTP id BDBEB48DD for ; Fri, 22 Aug 2003 11:44:06 -0600 (MDT) Date: Fri, 22 Aug 2003 10:36:34 -0700 From: "David S. Miller" To: Matthew Wilcox Cc: willy@debian.org, James.Bottomley@SteelEye.com, linux-kernel@vger.kernel.org, parisc-linux@lists.parisc-linux.org, drepper@redhat.com Subject: Re: [parisc-linux] Re: Problems with kernel mmap (failing tst-mmap-eofsync in glibc on parisc) Message-Id: <20030822103634.46a15747.davem@redhat.com> In-Reply-To: <20030822174103.GI18834@parcelfarce.linux.theplanet.co.uk> References: <1061563239.2090.25.camel@mulgrave> <20030822091447.6ecea6ca.davem@redhat.com> <20030822163429.GH18834@parcelfarce.linux.theplanet.co.uk> <20030822093900.4468c012.davem@redhat.com> <20030822174103.GI18834@parcelfarce.linux.theplanet.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: parisc-linux-admin@lists.parisc-linux.org Errors-To: parisc-linux-admin@lists.parisc-linux.org List-Help: List-Post: List-Subscribe: , List-Id: parisc-linux developers list List-Unsubscribe: , List-Archive: On Fri, 22 Aug 2003 18:41:03 +0100 Matthew Wilcox wrote: > Uhm. So what happens when the user has stored into the page and now > the kernel wants to read from it? There's still data in the cache for > the user mapping that's non-coherent with the kernel mapping. I see. This causes the page cache read flush_dcache_page() call not to trigger. I was very confused by the fact that this bug was explained by saying that "the shared mmap list that flush_dcache_page() checks". So the idea is that VM_SHARED should be set based upon whether we mmap() the thing writable _not_ whether the open() was done with write permission enabled. Yes, I agree with that.