From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com [209.85.220.48]) by kanga.kvack.org (Postfix) with ESMTP id 95D776B0069 for ; Fri, 28 Nov 2014 02:32:16 -0500 (EST) Received: by mail-pa0-f48.google.com with SMTP id rd3so6305792pab.35 for ; Thu, 27 Nov 2014 23:32:16 -0800 (PST) Received: from lgeamrelo02.lge.com (lgeamrelo02.lge.com. [156.147.1.126]) by mx.google.com with ESMTP id sf9si12930900pac.8.2014.11.27.23.32.13 for ; Thu, 27 Nov 2014 23:32:15 -0800 (PST) Date: Fri, 28 Nov 2014 16:35:24 +0900 From: Joonsoo Kim Subject: Re: [PATCH v3 2/8] mm/debug-pagealloc: prepare boottime configurable on/off Message-ID: <20141128073524.GC11802@js1304-P5Q-DELUXE> References: <1416816926-7756-1-git-send-email-iamjoonsoo.kim@lge.com> <1416816926-7756-3-git-send-email-iamjoonsoo.kim@lge.com> <1417091739.29407.95.camel@x220> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1417091739.29407.95.camel@x220> Sender: owner-linux-mm@kvack.org List-ID: To: Paul Bolle Cc: Valentin Rothberg , Andrew Morton , Mel Gorman , Johannes Weiner , Minchan Kim , Dave Hansen , Michal Nazarewicz , Jungsoo Son , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Nov 27, 2014 at 01:35:39PM +0100, Paul Bolle wrote: > Joonsoo, > > On Mon, 2014-11-24 at 17:15 +0900, Joonsoo Kim wrote: > > Until now, debug-pagealloc needs extra flags in struct page, so we need > > to recompile whole source code when we decide to use it. This is really > > painful, because it takes some time to recompile and sometimes rebuild is > > not possible due to third party module depending on struct page. > > So, we can't use this good feature in many cases. > > > > Now, we have the page extension feature that allows us to insert > > extra flags to outside of struct page. This gets rid of third party module > > issue mentioned above. And, this allows us to determine if we need extra > > memory for this page extension in boottime. With these property, we can > > avoid using debug-pagealloc in boottime with low computational overhead > > in the kernel built with CONFIG_DEBUG_PAGEALLOC. This will help our > > development process greatly. > > > > This patch is the preparation step to achive above goal. debug-pagealloc > > originally uses extra field of struct page, but, after this patch, it > > will use field of struct page_ext. Because memory for page_ext is > > allocated later than initialization of page allocator in CONFIG_SPARSEMEM, > > we should disable debug-pagealloc feature temporarily until initialization > > of page_ext. This patch implements this. > > > > v2: fix compile error on CONFIG_PAGE_POISONING > > > > Signed-off-by: Joonsoo Kim > > This patch is included in today's linux-next (ie, next-2o0141127) as > commit 1e491e9be4c9 ("mm/debug-pagealloc: prepare boottime configurable > on/off"). > > > [...] > > > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > > index 33a8acf..c7b22e7 100644 > > --- a/include/linux/mm_types.h > > +++ b/include/linux/mm_types.h > > @@ -10,7 +10,6 @@ > > #include > > #include > > #include > > -#include > > #include > > #include > > #include > > @@ -186,9 +185,6 @@ struct page { > > void *virtual; /* Kernel virtual address (NULL if > > not kmapped, ie. highmem) */ > > #endif /* WANT_PAGE_VIRTUAL */ > > -#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS > > - unsigned long debug_flags; /* Use atomic bitops on this */ > > -#endif > > > > #ifdef CONFIG_KMEMCHECK > > /* > > diff --git a/include/linux/page-debug-flags.h b/include/linux/page-debug-flags.h > > deleted file mode 100644 > > index 22691f61..0000000 > > --- a/include/linux/page-debug-flags.h > > +++ /dev/null > > @@ -1,32 +0,0 @@ > > -#ifndef LINUX_PAGE_DEBUG_FLAGS_H > > -#define LINUX_PAGE_DEBUG_FLAGS_H > > - > > -/* > > - * page->debug_flags bits: > > - * > > - * PAGE_DEBUG_FLAG_POISON is set for poisoned pages. This is used to > > - * implement generic debug pagealloc feature. The pages are filled with > > - * poison patterns and set this flag after free_pages(). The poisoned > > - * pages are verified whether the patterns are not corrupted and clear > > - * the flag before alloc_pages(). > > - */ > > - > > -enum page_debug_flags { > > - PAGE_DEBUG_FLAG_POISON, /* Page is poisoned */ > > - PAGE_DEBUG_FLAG_GUARD, > > -}; > > - > > -/* > > - * Ensure that CONFIG_WANT_PAGE_DEBUG_FLAGS reliably > > - * gets turned off when no debug features are enabling it! > > - */ > > - > > -#ifdef CONFIG_WANT_PAGE_DEBUG_FLAGS > > -#if !defined(CONFIG_PAGE_POISONING) && \ > > - !defined(CONFIG_PAGE_GUARD) \ > > -/* && !defined(CONFIG_PAGE_DEBUG_SOMETHING_ELSE) && ... */ > > -#error WANT_PAGE_DEBUG_FLAGS is turned on with no debug features! > > -#endif > > -#endif /* CONFIG_WANT_PAGE_DEBUG_FLAGS */ > > - > > -#endif /* LINUX_PAGE_DEBUG_FLAGS_H */ > > This remove all uses of CONFIG_WANT_PAGE_DEBUG_FLAGS and > CONFIG_PAGE_GUARD. So the Kconfig symbols WANT_PAGE_DEBUG_FLAGS and > PAGE_GUARD are now unused. > > Should I submit the trivial patch to remove these symbols or is a patch > that does that queued already? Hello, Paul. Thanks for spotting this. I attach the patch. :) Andrew, Could you kindly fold this into the patch in your tree? Thanks. ------------------->8---------------