From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755449AbbI1Rv3 (ORCPT ); Mon, 28 Sep 2015 13:51:29 -0400 Received: from mail-la0-f42.google.com ([209.85.215.42]:35542 "EHLO mail-la0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754178AbbI1Rv1 (ORCPT ); Mon, 28 Sep 2015 13:51:27 -0400 Date: Mon, 28 Sep 2015 20:51:23 +0300 From: "Kirill A. Shutemov" To: Konstantin Khlebnikov , Mel Gorman Cc: "Kirill A. Shutemov" , Andrew Morton , Andrea Arcangeli , Hugh Dickins , Dave Hansen , Rik van Riel , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Steve Capper , "Aneesh Kumar K.V" , Johannes Weiner , Michal Hocko , Jerome Marchand , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 03/16] page-flags: introduce page flags policies wrt compound pages Message-ID: <20150928175123.GA6590@node> References: <20150921153509.fef7ecdf313ef74307c43b65@linux-foundation.org> <1443106264-78075-1-git-send-email-kirill.shutemov@linux.intel.com> <1443106264-78075-4-git-send-email-kirill.shutemov@linux.intel.com> <56053E1D.7050001@yandex-team.ru> <20150925191307.GA25711@node.dhcp.inet.fi> <5609102B.5020704@yandex-team.ru> <20150928110305.GA4721@node> <560928FC.2090407@yandex-team.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <560928FC.2090407@yandex-team.ru> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 28, 2015 at 02:48:12PM +0300, Konstantin Khlebnikov wrote: > On 28.09.2015 14:03, Kirill A. Shutemov wrote: > >On Mon, Sep 28, 2015 at 01:02:19PM +0300, Konstantin Khlebnikov wrote: > >>On 25.09.2015 22:13, Kirill A. Shutemov wrote: > >>>On Fri, Sep 25, 2015 at 03:29:17PM +0300, Konstantin Khlebnikov wrote: > >>>>On 24.09.2015 17:50, Kirill A. Shutemov wrote: > >>>>>This patch adds a third argument to macros which create function > >>>>>definitions for page flags. This argument defines how page-flags helpers > >>>>>behave on compound functions. > >>>>> > >>>>>For now we define four policies: > >>>>> > >>>>>- PF_ANY: the helper function operates on the page it gets, regardless > >>>>> if it's non-compound, head or tail. > >>>>> > >>>>>- PF_HEAD: the helper function operates on the head page of the compound > >>>>> page if it gets tail page. > >>>>> > >>>>>- PF_NO_TAIL: only head and non-compond pages are acceptable for this > >>>>> helper function. > >>>>> > >>>>>- PF_NO_COMPOUND: only non-compound pages are acceptable for this helper > >>>>> function. > >>>>> > >>>>>For now we use policy PF_ANY for all helpers, which matches 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. > >>>>> > >>>>>Signed-off-by: Kirill A. Shutemov > >>>>>--- > >>>>> include/linux/page-flags.h | 154 ++++++++++++++++++++++++++------------------- > >>>>> 1 file changed, 90 insertions(+), 64 deletions(-) > >>>>> > >>>>>diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > >>>>>index 713d3f2c2468..1b3babe5ff69 100644 > >>>>>--- a/include/linux/page-flags.h > >>>>>+++ b/include/linux/page-flags.h > >>>>>@@ -154,49 +154,68 @@ static inline int PageCompound(struct page *page) > >>>>> return test_bit(PG_head, &page->flags) || PageTail(page); > >>>>> } > >>>>> > >>>>>+/* Page flags policies wrt compound pages */ > >>>>>+#define PF_ANY(page, enforce) page > >>>>>+#define PF_HEAD(page, enforce) compound_head(page) > >>>>>+#define PF_NO_TAIL(page, enforce) ({ \ > >>>>>+ if (enforce) \ > >>>>>+ VM_BUG_ON_PAGE(PageTail(page), page); \ > >>>>>+ else \ > >>>>>+ page = compound_head(page); \ > >>>>>+ page;}) > >>>>>+#define PF_NO_COMPOUND(page, enforce) ({ \ > >>>>>+ if (enforce) \ > >>>>>+ VM_BUG_ON_PAGE(PageCompound(page), page); \ > >>>> > >>>>Linux next-20150925 crashes here (at least in lkvm) > >>>>if CONFIG_DEFERRED_STRUCT_PAGE_INIT=y > >>> > >>>Hm. I don't see the crash in qemu. Could you share your config? > >> > >>see in attachment > > > >Still don't see it. Have you tried patch from my previous mail? > > > > Just checked: patch fixes oops. > > > This part of 7e18adb4f80bea90d30b62158694d97c31f71d37 > (mm: meminit: initialise remaining struct pages in parallel with kswapd) > is unclear: > > +#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT > +static void init_reserved_page(unsigned long pfn) > +{ > + pg_data_t *pgdat; > + int nid, zid; > + > + if (!early_page_uninitialised(pfn)) > + return; > + > + nid = early_pfn_to_nid(pfn); > + pgdat = NODE_DATA(nid); > + > + for (zid = 0; zid < MAX_NR_ZONES; zid++) { > + struct zone *zone = &pgdat->node_zones[zid]; > + > + if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone)) > + break; > + } > + __init_single_pfn(pfn, zid, nid); > +} > +#else > +static inline void init_reserved_page(unsigned long pfn) > +{ > +} > +#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */ > + > /* > * Initialised pages do not have PageReserved set. This function is > * called for each range allocated by the bootmem allocator and > * marks the pages PageReserved. The remaining valid pages are later > * sent to the buddy page allocator. > */ > -void reserve_bootmem_region(unsigned long start, unsigned long end) > +void __meminit reserve_bootmem_region(unsigned long start, unsigned long > end) > { > unsigned long start_pfn = PFN_DOWN(start); > unsigned long end_pfn = PFN_UP(end); > > - for (; start_pfn < end_pfn; start_pfn++) > - if (pfn_valid(start_pfn)) > - SetPageReserved(pfn_to_page(start_pfn)); > + for (; start_pfn < end_pfn; start_pfn++) { > + if (pfn_valid(start_pfn)) { > + struct page *page = pfn_to_page(start_pfn); > + > + init_reserved_page(start_pfn); > + SetPageReserved(page); > + } > + } > } > > We leave struct page uninitialized but call SetPageReserved for it. __init_single_pfn() initializes the page. I guess the problem is false-negative reply from early_page_uninitialised(). No idea why it could happen. Mel? -- Kirill A. Shutemov