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=-8.5 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 A53DEC43381 for ; Thu, 21 Mar 2019 14:57:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5865420850 for ; Thu, 21 Mar 2019 14:57:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5865420850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DF8506B0010; Thu, 21 Mar 2019 10:57:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D7F5E6B0269; Thu, 21 Mar 2019 10:57:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C20BF6B026B; Thu, 21 Mar 2019 10:57:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 6EF5B6B0010 for ; Thu, 21 Mar 2019 10:57:49 -0400 (EDT) Received: by mail-ed1-f72.google.com with SMTP id l19so2302437edr.12 for ; Thu, 21 Mar 2019 07:57:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:date:from:to :cc:subject:message-id:references:mime-version:content-disposition :in-reply-to:user-agent; bh=i2uSTCGkfQuL3YOlx+NsfZROp2req3n+zLD2kKxzDZ8=; b=HVC5/f7GRr49Isf3Ad16ZNsMkloBYLM4dJZ+lsWoo3kFlei12k48b56NpVvd8Z/Cr0 ADQHXNnE09vHVNSWPbkrbdyOF+bxzn/ngn1p/iJa15V3rwLkrx9s5SvPS09dPAiwo+gH 9aOmmJQbDwaVwK9Njm5FloHO+EaEbmZEz6TUtxHzSiAmtEKzDq/FsatmGYbQa5n6n+15 RvnisnyTOJwPfmTXS/RRn39MEGae3bBASmWUQtQ78b4DNor0p8f54HIhjW2jstFBqXeF hfpeInQ+KVmXUsntmrzmYR0Dh5+4q2T/gRX1XCRUwwCN3eD2FKHE+KDjHogKC0GbdpnP TsZQ== X-Original-Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Gm-Message-State: APjAAAWiwjn6EY4ycpSWazVZsmzSgNpCF/lraEftIaejItEnSuoWYJqA IVLZ9jDKBiGvLWmsVDy8D3gkgQnUBaA4QcCvionT6342EAmJX697DxuVrxhH95Jq3s98f49HRLq aPlF+z60rQM1EI8mYJTwWou8Rx51M4PO13eBqvk4lzSqSGZQm6KffZvDgvz4pmEo= X-Received: by 2002:aa7:dc5a:: with SMTP id g26mr2790595edu.273.1553180269005; Thu, 21 Mar 2019 07:57:49 -0700 (PDT) X-Google-Smtp-Source: APXvYqxMYXtu6K9khMZVxXgFhQbPhtF/huU2F03bwG/Mh5paW0R3R05CYMhE8PygUKSl1neApZPI X-Received: by 2002:aa7:dc5a:: with SMTP id g26mr2790546edu.273.1553180267826; Thu, 21 Mar 2019 07:57:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1553180267; cv=none; d=google.com; s=arc-20160816; b=g6O8yV8th4Pkaf7Ymb5iQWiETFIJtxYuQ+Jy5sNpssQVFt7STQI+vbvcMbyC2HL3HN gOgtu4gZA6kk/ld/bXFryvjQjIRRAUsYYSelpy8Ke0/jOmsHjwd2kIyBelszk33/oog8 RkcU7qvMDrlsmHXu10UmQ3SCgKsM+INwog2QPC6Qb9EsgqGeNzTqtkiAgOj6ti54Gn9a KYAa8VUkzrc1CeSnSnGCZGfB1g1fiz4eQyX8ShO15+5o9alJYcWrqMvHqkbqsYd3M5+i opObkSnR9O7XpC/mIj11dL6lWkoGF/ZIWSF9qSVWoxWCNcmqAkzuImfp6N+NnVNUxO0I ystg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date; bh=i2uSTCGkfQuL3YOlx+NsfZROp2req3n+zLD2kKxzDZ8=; b=W9eBHVgczyUhfwZwaf822uLa/N9Hh2j88OPjtuH/VSd41VEEo/jKsCL+ooxweg1aBh fKesIc1un2u14VOh7KUEBFToAUgObv10emFD1AbFdUqNRyTj5tgLFNTOKklc9UaRYfq3 ipAy309vi7BLSFyQdWEP+J1QgYrhhWJ4khaqX8EeIhapdvuKon3V4bs+LNrfw9hkx1pV rJSVv3DTAgw/Yz/rEI6f1UygbnReKNx/3Y4B5QsKdDuU7bouQ6mASX8vTC13jZVKhSou rHdgDk2L1ZeIYbCJliAfNwywVvX5ojo7K6Al3464tkeqrgHpoNnblNEaRBHUXq8Mwg7S 4afQ== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id y1si792435edp.441.2019.03.21.07.57.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 21 Mar 2019 07:57:47 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CD105ABDC; Thu, 21 Mar 2019 14:57:46 +0000 (UTC) Date: Thu, 21 Mar 2019 15:57:45 +0100 From: Michal Hocko To: Yang Shi Cc: mgorman@techsingularity.net, vbabka@suse.cz, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] mm: mempolicy: remove MPOL_MF_LAZY Message-ID: <20190321145745.GS8696@dhcp22.suse.cz> References: <1553041659-46787-1-git-send-email-yang.shi@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1553041659-46787-1-git-send-email-yang.shi@linux.alibaba.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 20-03-19 08:27:39, Yang Shi wrote: > MPOL_MF_LAZY was added by commit b24f53a0bea3 ("mm: mempolicy: Add > MPOL_MF_LAZY"), then it was disabled by commit a720094ded8c ("mm: > mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now") > right away in 2012. So, it is never ever exported to userspace. > > And, it looks nobody is interested in revisiting it since it was > disabled 7 years ago. So, it sounds pointless to still keep it around. The above changelog owes us a lot of explanation about why this is safe and backward compatible. I am also not sure you can change MPOL_MF_INTERNAL because somebody still might use the flag from userspace and we want to guarantee it will have the exact same semantic. > Cc: Mel Gorman > Cc: Michal Hocko > Cc: Vlastimil Babka > Signed-off-by: Yang Shi > --- > Hi folks, > I'm not sure if you still would like to revisit it later. And, I may be > not the first one to try to remvoe it. IMHO, it sounds pointless to still > keep it around if nobody is interested in it. > > include/uapi/linux/mempolicy.h | 3 +-- > mm/mempolicy.c | 13 ------------- > 2 files changed, 1 insertion(+), 15 deletions(-) > > diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h > index 3354774..eb52a7a 100644 > --- a/include/uapi/linux/mempolicy.h > +++ b/include/uapi/linux/mempolicy.h > @@ -45,8 +45,7 @@ enum { > #define MPOL_MF_MOVE (1<<1) /* Move pages owned by this process to conform > to policy */ > #define MPOL_MF_MOVE_ALL (1<<2) /* Move every page to conform to policy */ > -#define MPOL_MF_LAZY (1<<3) /* Modifies '_MOVE: lazy migrate on fault */ > -#define MPOL_MF_INTERNAL (1<<4) /* Internal flags start here */ > +#define MPOL_MF_INTERNAL (1<<3) /* Internal flags start here */ > > #define MPOL_MF_VALID (MPOL_MF_STRICT | \ > MPOL_MF_MOVE | \ > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index af171cc..67886f4 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -593,15 +593,6 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end, > > qp->prev = vma; > > - if (flags & MPOL_MF_LAZY) { > - /* Similar to task_numa_work, skip inaccessible VMAs */ > - if (!is_vm_hugetlb_page(vma) && > - (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) && > - !(vma->vm_flags & VM_MIXEDMAP)) > - change_prot_numa(vma, start, endvma); > - return 1; > - } > - > /* queue pages from current vma */ > if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) > return 0; > @@ -1181,9 +1172,6 @@ static long do_mbind(unsigned long start, unsigned long len, > if (IS_ERR(new)) > return PTR_ERR(new); > > - if (flags & MPOL_MF_LAZY) > - new->flags |= MPOL_F_MOF; > - > /* > * If we are using the default policy then operation > * on discontinuous address spaces is okay after all > @@ -1226,7 +1214,6 @@ static long do_mbind(unsigned long start, unsigned long len, > int nr_failed = 0; > > if (!list_empty(&pagelist)) { > - WARN_ON_ONCE(flags & MPOL_MF_LAZY); > nr_failed = migrate_pages(&pagelist, new_page, NULL, > start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND); > if (nr_failed) > -- > 1.8.3.1 > -- Michal Hocko SUSE Labs