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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39924C433EF for ; Wed, 6 Oct 2021 15:29:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C3AAD61040 for ; Wed, 6 Oct 2021 15:29:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C3AAD61040 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 65E596B0071; Wed, 6 Oct 2021 11:29:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 60E026B0073; Wed, 6 Oct 2021 11:29:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4FD146B0074; Wed, 6 Oct 2021 11:29:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0253.hostedemail.com [216.40.44.253]) by kanga.kvack.org (Postfix) with ESMTP id 411976B0071 for ; Wed, 6 Oct 2021 11:29:45 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 070F92C58A for ; Wed, 6 Oct 2021 15:29:45 +0000 (UTC) X-FDA: 78666397530.18.CD2D629 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf13.hostedemail.com (Postfix) with ESMTP id 7471C103B960 for ; Wed, 6 Oct 2021 15:29:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=HVJLkxV8KXTKQ/73bUbSbkDvZ1xhZ4iTaPTxuxYbi3k=; b=aYLZWTTBDxcHDI3FWx07sgiLY9 IuENJawX4udoSekO9rglP046BDSYIU1MxrgSNuSEO/YEJXA3+0K5OW/4yqZYnS9l1Vwz82JfaeZQO kgVXWU9NVQVvzfPDVmRnGkkb77PuoyhZEFQPQw1AvwT4FD+43uYROeA5mBWTV/r/dckfp4xei5LuV OdVddo8ZdcJk2ZZt6EVXRNB5sIaZlrW3LMLi4KzF59zDPd1WRQb+Wfn16W+ha31kMZM1PwbiVhS/B qX1mJ4GFR0TrtOPUys9mwwiqUdnHR6CNKegYWOIHO/HiYNdpaQy8eHoz8FaYo9/Qbr+u6gB3PnJim bV8Jp+OA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mY8qq-0011bF-KD; Wed, 06 Oct 2021 15:29:15 +0000 Date: Wed, 6 Oct 2021 16:29:00 +0100 From: Matthew Wilcox To: David Hildenbrand Cc: linux-mm@kvack.org, Kent Overstreet , Johannes Weiner , linux-fsdevel@vger.kernel.org Subject: Re: [RFC] pgflags_t Message-ID: References: <89efcd40-9b56-00d4-1e29-9ad337b35426@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <89efcd40-9b56-00d4-1e29-9ad337b35426@redhat.com> Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=aYLZWTTB; spf=none (imf13.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 7471C103B960 X-Stat-Signature: teo3ar6rxkskeeg3cqn4uks5jphoq3bc X-HE-Tag: 1633534184-852124 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Oct 06, 2021 at 05:16:51PM +0200, David Hildenbrand wrote: > On 06.10.21 16:58, Matthew Wilcox wrote: > > David expressed some unease about the lack of typesafety in patches > > 1 & 2 of the page->slab conversion [1], and I'll admit to not being > > I yet have to reply to your mail (-EBUSY), I'd even enjoy doing all > pgflags_t access via the struct page, for example, using simpler "reserved" > placeholders for such fields in "struct slab" that we really want to move > out of struct slab later. When accessing flags, we'd cast to "struct page" > and do the access. There are several bits that slab/slob/slub use in page->flags currently. The obvious one is the node ID (whether stored directly or indirected via section), but also PG_pfmemalloc (aka PG_active), PG_slob_free (aka PG_private), PG_lock, PG_slab and PG_head, We might be able to change that too, but for the moment, how about we not explore that path in the interest of getting something merged that won't preclude exploring that path sometime in the future? > ... but whatever approach we use on that fron, this patch is a step into the > right direction IMHO. Thank you!