From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933318AbbI1LsZ (ORCPT ); Mon, 28 Sep 2015 07:48:25 -0400 Received: from forward-corp1f.mail.yandex.net ([95.108.130.40]:46772 "EHLO forward-corp1f.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932771AbbI1LsX (ORCPT ); Mon, 28 Sep 2015 07:48:23 -0400 Authentication-Results: smtpcorp4.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Subject: Re: [PATCH 03/16] page-flags: introduce page flags policies wrt compound pages To: "Kirill A. Shutemov" 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> Cc: "Kirill A. Shutemov" , Andrew Morton , 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 , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org From: Konstantin Khlebnikov Message-ID: <560928FC.2090407@yandex-team.ru> Date: Mon, 28 Sep 2015 14:48:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20150928110305.GA4721@node> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -- Konstantin