Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751640AbaK0FHz (ORCPT ); Thu, 27 Nov 2014 00:07:55 -0500 Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:51842 "EHLO lgemrelse7q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750754AbaK0FHx (ORCPT ); Thu, 27 Nov 2014 00:07:53 -0500 X-Original-SENDERIP: 10.177.222.213 X-Original-MAILFROM: iamjoonsoo.kim@lge.com Date: Thu, 27 Nov 2014 14:10:59 +0900 From: Joonsoo Kim To: Andrew Morton Cc: Mel Gorman , Johannes Weiner , Minchan Kim , Dave Hansen , Michal Nazarewicz , Jungsoo Son , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 3/8] mm/debug-pagealloc: make debug-pagealloc boottime configurable Message-ID: <20141127051059.GA6755@js1304-P5Q-DELUXE> References: <1416816926-7756-1-git-send-email-iamjoonsoo.kim@lge.com> <1416816926-7756-4-git-send-email-iamjoonsoo.kim@lge.com> <20141124145542.08b97076.akpm@linux-foundation.org> <20141124234237.GA7824@js1304-P5Q-DELUXE> <20141126124936.56cc901e13f27927d7b42aaf@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141126124936.56cc901e13f27927d7b42aaf@linux-foundation.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 26, 2014 at 12:49:36PM -0800, Andrew Morton wrote: > On Tue, 25 Nov 2014 08:42:37 +0900 Joonsoo Kim wrote: > > > On Mon, Nov 24, 2014 at 02:55:42PM -0800, Andrew Morton wrote: > > > On Mon, 24 Nov 2014 17:15:21 +0900 Joonsoo Kim wrote: > > > > > > > Now, we have prepared to avoid using debug-pagealloc in boottime. So > > > > introduce new kernel-parameter to disable debug-pagealloc in boottime, > > > > and makes related functions to be disabled in this case. > > > > > > > > Only non-intuitive part is change of guard page functions. Because > > > > guard page is effective only if debug-pagealloc is enabled, turning off > > > > according to debug-pagealloc is reasonable thing to do. > > > > > > > > ... > > > > > > > > --- a/Documentation/kernel-parameters.txt > > > > +++ b/Documentation/kernel-parameters.txt > > > > @@ -858,6 +858,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > > > > causing system reset or hang due to sending > > > > INIT from AP to BSP. > > > > > > > > + disable_debug_pagealloc > > > > + [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this > > > > + parameter allows user to disable it at boot time. > > > > + With this parameter, we can avoid allocating huge > > > > + chunk of memory for debug pagealloc and then > > > > + the system will work mostly same with the kernel > > > > + built without CONFIG_DEBUG_PAGEALLOC. > > > > + > > > > > > Weren't we going to make this default to "off", require a boot option > > > to turn debug_pagealloc on? > > > > Hello, Andrew. > > > > I'm afraid that changing default to "off" confuses some old users. > > They would expect that it is default "on". But, it is just debug > > feature, so, it may be no problem. If you prefer to change default, I > > will rework this patch. Please let me know your decision. > > I suspect the number of "old users" is one ;) > > I think it would be better to default to off - that's the typical > behaviour for debug features, for good reasons. Okay. Here goes the patch. ------------->8---------------- >From 799eba44b2d071d55e4444399be63f1af0aff204 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Wed, 5 Nov 2014 16:05:14 +0900 Subject: [PATCH v4] mm/debug-pagealloc: make debug-pagealloc boottime configurable Now, we have prepared to avoid using debug-pagealloc in boottime. So, make it disabled in default and introduce new kernel-parameter to enable debug-pagealloc in boottime. This is a debugging feature, so default disabled may be more useful. Only non-intuitive part is change of guard page functions. Because guard page is effective only if debug-pagealloc is enabled, turning on/off according to debug-pagealloc is reasonable thing to do. v2: makes debug-pagealloc boottime configurable for page poisoning, too v4: makes debug-pagealloc disabled in default Signed-off-by: Joonsoo Kim --- Documentation/kernel-parameters.txt | 9 +++++++++ arch/powerpc/mm/hash_utils_64.c | 2 +- arch/powerpc/mm/pgtable_32.c | 2 +- arch/s390/mm/pageattr.c | 2 +- arch/sparc/mm/init_64.c | 2 +- arch/x86/mm/pageattr.c | 2 +- include/linux/mm.h | 17 ++++++++++++++++- mm/debug-pagealloc.c | 8 +++++++- mm/page_alloc.c | 20 ++++++++++++++++++++ 9 files changed, 57 insertions(+), 7 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 3c5a178..e35bfcc 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -829,6 +829,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. CONFIG_DEBUG_PAGEALLOC, hence this option will not help tracking down these problems. + debug_pagealloc= + [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this + parameter enables the feature at boot time. In + default, it is disabled. We can avoid allocating huge + chunk of memory for debug pagealloc if we don't enable + it at boot time and the system will work mostly same + with the kernel built without CONFIG_DEBUG_PAGEALLOC. + on: enable the feature + debugpat [X86] Enable PAT debugging decnet.addr= [HW,NET] diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index d5339a3..57b9c23 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -1432,7 +1432,7 @@ static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi) mmu_kernel_ssize, 0); } -void kernel_map_pages(struct page *page, int numpages, int enable) +void __kernel_map_pages(struct page *page, int numpages, int enable) { unsigned long flags, vaddr, lmi; int i; diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c index cf11342..b98aac6 100644 --- a/arch/powerpc/mm/pgtable_32.c +++ b/arch/powerpc/mm/pgtable_32.c @@ -430,7 +430,7 @@ static int change_page_attr(struct page *page, int numpages, pgprot_t prot) } -void kernel_map_pages(struct page *page, int numpages, int enable) +void __kernel_map_pages(struct page *page, int numpages, int enable) { if (PageHighMem(page)) return; diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index 3fef3b2..426c9d4 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -120,7 +120,7 @@ static void ipte_range(pte_t *pte, unsigned long address, int nr) } } -void kernel_map_pages(struct page *page, int numpages, int enable) +void __kernel_map_pages(struct page *page, int numpages, int enable) { unsigned long address; int nr, i, j; diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c index 2d91c62..3ea267c 100644 --- a/arch/sparc/mm/init_64.c +++ b/arch/sparc/mm/init_64.c @@ -1621,7 +1621,7 @@ static void __init kernel_physical_mapping_init(void) } #ifdef CONFIG_DEBUG_PAGEALLOC -void kernel_map_pages(struct page *page, int numpages, int enable) +void __kernel_map_pages(struct page *page, int numpages, int enable) { unsigned long phys_start = page_to_pfn(page) << PAGE_SHIFT; unsigned long phys_end = phys_start + (numpages * PAGE_SIZE); diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 36de293..4d304e1 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -1801,7 +1801,7 @@ static int __set_pages_np(struct page *page, int numpages) return __change_page_attr_set_clr(&cpa, 0); } -void kernel_map_pages(struct page *page, int numpages, int enable) +void __kernel_map_pages(struct page *page, int numpages, int enable) { if (PageHighMem(page)) return; diff --git a/include/linux/mm.h b/include/linux/mm.h index 5a8d4d4..5dc11e7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2055,7 +2055,22 @@ static inline void vm_stat_account(struct mm_struct *mm, #endif /* CONFIG_PROC_FS */ #ifdef CONFIG_DEBUG_PAGEALLOC -extern void kernel_map_pages(struct page *page, int numpages, int enable); +extern bool _debug_pagealloc_enabled; +extern void __kernel_map_pages(struct page *page, int numpages, int enable); + +static inline bool debug_pagealloc_enabled(void) +{ + return _debug_pagealloc_enabled; +} + +static inline void +kernel_map_pages(struct page *page, int numpages, int enable) +{ + if (!debug_pagealloc_enabled()) + return; + + __kernel_map_pages(page, numpages, enable); +} #ifdef CONFIG_HIBERNATION extern bool kernel_page_present(struct page *page); #endif /* CONFIG_HIBERNATION */ diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c index 0072f2c..5bf5906 100644 --- a/mm/debug-pagealloc.c +++ b/mm/debug-pagealloc.c @@ -10,11 +10,17 @@ static bool page_poisoning_enabled __read_mostly; static bool need_page_poisoning(void) { + if (!debug_pagealloc_enabled()) + return false; + return true; } static void init_page_poisoning(void) { + if (!debug_pagealloc_enabled()) + return; + page_poisoning_enabled = true; } @@ -119,7 +125,7 @@ static void unpoison_pages(struct page *page, int n) unpoison_page(page + i); } -void kernel_map_pages(struct page *page, int numpages, int enable) +void __kernel_map_pages(struct page *page, int numpages, int enable) { if (!page_poisoning_enabled) return; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7534733..10310ad 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -426,15 +426,35 @@ static inline void prep_zero_page(struct page *page, unsigned int order, #ifdef CONFIG_DEBUG_PAGEALLOC unsigned int _debug_guardpage_minorder; +bool _debug_pagealloc_enabled __read_mostly; bool _debug_guardpage_enabled __read_mostly; +static int __init early_debug_pagealloc(char *buf) +{ + if (!buf) + return -EINVAL; + + if (strcmp(buf, "on") == 0) + _debug_pagealloc_enabled = true; + + return 0; +} +early_param("debug_pagealloc", early_debug_pagealloc); + static bool need_debug_guardpage(void) { + /* If we don't use debug_pagealloc, we don't need guard page */ + if (!debug_pagealloc_enabled()) + return false; + return true; } static void init_debug_guardpage(void) { + if (!debug_pagealloc_enabled()) + return; + _debug_guardpage_enabled = true; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/