From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BECD2C4360F for ; Tue, 12 Mar 2019 04:35:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8032E214D8 for ; Tue, 12 Mar 2019 04:35:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazonses.com header.i=@amazonses.com header.b="dPZiNMzA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726273AbfCLEfQ (ORCPT ); Tue, 12 Mar 2019 00:35:16 -0400 Received: from a9-46.smtp-out.amazonses.com ([54.240.9.46]:54406 "EHLO a9-46.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725792AbfCLEfQ (ORCPT ); Tue, 12 Mar 2019 00:35:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1552365315; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=IbeuS+zdcBFTccbustqiwuLJ9wpMqCNVsFWBtNbKAts=; b=dPZiNMzAgEKy+d5R3GmABBmXu0+p3BIgveTRcb7Y/V7shB2pxnRd55Rqpq7Yz/RQ 7+pnOikBn+Tz2XvX+HJq2s3moWzsIlT6WXoDzB+cHCSn8yPHAMbQ+c+XWdpOzK9LIjj 1sdDXaJUK9OT5kVjMh14wrdnAv2+iM2QHZ5z4Jjw= Date: Tue, 12 Mar 2019 04:35:15 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Roman Gushchin cc: "Tobin C. Harding" , Andrew Morton , Pekka Enberg , Matthew Wilcox , Tycho Andersen , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC 02/15] slub: Add isolate() and migrate() methods In-Reply-To: <20190311215106.GA7915@tower.DHCP.thefacebook.com> Message-ID: <01000169702ee357-fe8b85e5-e601-41da-8ba2-25e8b7db52eb-000000@email.amazonses.com> References: <20190308041426.16654-1-tobin@kernel.org> <20190308041426.16654-3-tobin@kernel.org> <20190311215106.GA7915@tower.DHCP.thefacebook.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SES-Outgoing: 2019.03.12-54.240.9.46 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 11 Mar 2019, Roman Gushchin wrote: > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -4325,6 +4325,34 @@ int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags) > > return err; > > } > > > > +void kmem_cache_setup_mobility(struct kmem_cache *s, > > + kmem_cache_isolate_func isolate, > > + kmem_cache_migrate_func migrate) > > +{ > > I wonder if it's better to adapt kmem_cache_create() to take two additional > argument? I suspect mobility is not a dynamic option, so it can be > set on kmem_cache creation. One other idea that prior versions of this patchset used was to change kmem_cache_create() so that the ctor parameter becomes an ops vector. However, in order to reduce the size of the patchset I dropped that. It could be easily moved back to the way it was before. > > + /* > > + * Sadly serialization requirements currently mean that we have > > + * to disable fast cmpxchg based processing. > > + */ > > Can you, please, elaborate a bit more here? cmpxchg based processing does not lock the struct page. SMO requires to ensure that all changes on a slab page can be stopped. The page->lock will accomplish that. I think we could avoid dealing with actually locking the page with some more work.