From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: Best way to pin a page in ext4? Date: Wed, 17 Sep 2014 15:57:19 +0200 Message-ID: <20140917135719.GK2840@worktop.localdomain> References: <20140915185102.0944158037A@closure.thunk.org> <36321733-F488-49E3-8733-C6758F83DFA1@dilger.ca> <20140916180759.GI6205@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Hugh Dickins , Theodore Ts'o , Andreas Dilger , linux-mm , linux-ext4@vger.kernel.org To: Christoph Lameter Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On Tue, Sep 16, 2014 at 10:31:24PM -0500, Christoph Lameter wrote: > On Tue, 16 Sep 2014, Hugh Dickins wrote: > > > On the page migration issue: it's not quite as straightforward as > > Christoph suggests. He and I agree completely that mlocked pages > > should be migratable, but some real-time-minded people disagree: > > so normal compaction is still forbidden to migrate mlocked pages in > > the vanilla kernel (though we in Google patch that prohibition out). > > So pinning by refcount is no worse for compaction than mlocking, > > in the vanilla kernel. > > Note though that compaction is not the only mechanism that uses page > migration. Agreed, and not all migration paths check for mlocked iirc. ISTR it is very much possible for mlocked pages to get migrated in mainline. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org