From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f172.google.com (mail-we0-f172.google.com [74.125.82.172]) by kanga.kvack.org (Postfix) with ESMTP id EC90E6B0038 for ; Fri, 20 Mar 2015 17:35:07 -0400 (EDT) Received: by weop45 with SMTP id p45so91708726weo.0 for ; Fri, 20 Mar 2015 14:35:07 -0700 (PDT) Received: from jenni1.inet.fi (mta-out1.inet.fi. [62.71.2.227]) by mx.google.com with ESMTP id ex5si489831wic.96.2015.03.20.14.35.06 for ; Fri, 20 Mar 2015 14:35:06 -0700 (PDT) Date: Fri, 20 Mar 2015 23:34:49 +0200 From: "Kirill A. Shutemov" Subject: Re: [PATCH 03/16] page-flags: introduce page flags policies wrt compound pages Message-ID: <20150320213449.GA19774@node.dhcp.inet.fi> References: <1426784902-125149-1-git-send-email-kirill.shutemov@linux.intel.com> <1426784902-125149-4-git-send-email-kirill.shutemov@linux.intel.com> <20150320133553.eb8576a5ff1e85f201690628@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150320133553.eb8576a5ff1e85f201690628@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Hugh Dickins , Dave Hansen , Mel Gorman , Rik van Riel , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , Jerome Marchand , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, Mar 20, 2015 at 01:35:53PM -0700, Andrew Morton wrote: > On Thu, 19 Mar 2015 19:08:09 +0200 "Kirill A. Shutemov" wrote: > > > This patch third argument to macros which create function definitions > > for page flags. This arguments defines how page-flags helpers behave > > on compound functions. > > > > For now we define four policies: > > > > - ANY: the helper function operates on the page it gets, regardless if > > it's non-compound, head or tail. > > > > - HEAD: the helper function operates on the head page of the compound > > page if it gets tail page. > > > > - NO_TAIL: only head and non-compond pages are acceptable for this > > helper function. > > > > - NO_COMPOUND: only non-compound pages are acceptable for this helper > > function. > > > > For now we use policy ANY for all helpers, which match current > > behaviour. > > > > We do not enforce the policy for TESTPAGEFLAG, because we have flags > > checked for random pages all over the kernel. Noticeable exception to > > this is PageTransHuge() which triggers VM_BUG_ON() for tail page. > > > > +/* Page flags policies wrt compound pages */ > > +#define ANY(page, enforce) page > > +#define HEAD(page, enforce) compound_head(page) > > +#define NO_TAIL(page, enforce) ({ \ > > +#define NO_COMPOUND(page, enforce) ({ \ > > ... > > > > +#undef ANY > > +#undef HEAD > > +#undef NO_TAIL > > +#undef NO_COMPOUND > > #endif /* !__GENERATING_BOUNDS_H */ > > This is risky - there are existing definitions of ANY and HEAD, and > this code may go and undefine them. This is improbable at present, as > those definitions are in .c, after all includes. But still, it's not > good to chew off great hunks of the namespace like this. > > So I think I'll prefix all these with "PF_", OK? Yeah. That's fine. -- Kirill A. Shutemov -- 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