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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 BC6B6C83003 for ; Wed, 29 Apr 2020 07:34:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9ABB3206D9 for ; Wed, 29 Apr 2020 07:34:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726420AbgD2HeP (ORCPT ); Wed, 29 Apr 2020 03:34:15 -0400 Received: from mail-oi1-f196.google.com ([209.85.167.196]:43776 "EHLO mail-oi1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726355AbgD2HeP (ORCPT ); Wed, 29 Apr 2020 03:34:15 -0400 Received: by mail-oi1-f196.google.com with SMTP id j16so956311oih.10 for ; Wed, 29 Apr 2020 00:34:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SyWquW6C3h9yYRPnL8ZX6mVqONgOMsOlS/nbLkzCvR8=; b=Q7b1WloH3BNWLKrfpG7q1BWRxDDIlc4cnuGijD2OuPAT89XUyE0HqkTLAQSs0yHVY6 IVIg8IbL+mSskV/zWYRVBPLgAKGJba/pnwHGG38l6HYjhaOZd9rQT3Jb9V+ycK4Cl4OG 70UzW1J4NNlhJXUP4KHEYNG6+9wZNc+T7NNhCdjvuBypQ2tVG1QuNf3bH0mGvuKgxrqM F1oruI9MJvCTy5HVDuDc9bA7UqFInRIi5T14xfXW6vgtN8sVmuaUqGhy3B8G8yR3yWKm VftCjDiWrdFBATEyz80q3KhjUPKK4z53ldthPzlD+qlV/qTdeGNlOmZC70MtQXortLsY 1daw== X-Gm-Message-State: AGi0Pub2a345ncbkPH7oYCzujCMVdUHDoOAQO8g/+OrMriSDMEVrjHCP 74cEVjU9ILtTdu+n5djhXgGw+/6Oxar+VmQy0aY= X-Google-Smtp-Source: APiQypJAsZR6cJVnPhd52DhYQokiZWeX1PxL/6m2Vvtp1dgHuL2QQU2M5utJVEIEaKuPsXF6mplj99rnUrUZngmlKtw= X-Received: by 2002:aca:d50f:: with SMTP id m15mr810760oig.54.1588145654121; Wed, 29 Apr 2020 00:34:14 -0700 (PDT) MIME-Version: 1.0 References: <20200428194449.22615-1-willy@infradead.org> <20200428194449.22615-3-willy@infradead.org> In-Reply-To: <20200428194449.22615-3-willy@infradead.org> From: Geert Uytterhoeven Date: Wed, 29 Apr 2020 09:34:02 +0200 Message-ID: Subject: Re: [PATCH 2/7] mm: Move pt_mm within struct page To: Matthew Wilcox Cc: Linux MM , Linux Kernel Mailing List , Linux ARM , Will Deacon , Catalin Marinas , Russell King , linux-m68k Content-Type: text/plain; charset="UTF-8" Sender: linux-m68k-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Hi Matthew, On Tue, Apr 28, 2020 at 9:44 PM Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" > Instead of a per-arch word within struct page, use a formerly reserved > word. This word is shared with page->mapping, so it must be cleared > before being freed as it is checked in free_pages(). > > Signed-off-by: Matthew Wilcox (Oracle) Thanks for your patch! > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -149,11 +149,8 @@ struct page { > pgtable_t pmd_huge_pte; > }; > }; > - unsigned long _pt_pad_2; /* mapping */ > - union { > - struct mm_struct *pt_mm; /* x86 pgds only */ > - atomic_t pt_frag_refcount; /* powerpc */ > - }; > + struct mm_struct *pt_mm; > + atomic_t pt_frag_refcount; /* powerpc */ So here is now an implicit hole on 64-bit platforms, right? Do we have any where alignof(long) != 8? > #if ALLOC_SPLIT_PTLOCKS > spinlock_t *ptl; > #else Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds