Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754681Ab3JUIxj (ORCPT ); Mon, 21 Oct 2013 04:53:39 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39932 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754516Ab3JUIxf (ORCPT ); Mon, 21 Oct 2013 04:53:35 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Mel Gorman" , "David Rientjes" , "Michal Hocko" , "Dave Hansen" , "Linus Torvalds" Date: Mon, 21 Oct 2013 09:46:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 148/149] mm, show_mem: suppress page counts in non-blockable contexts In-Reply-To: X-SA-Exim-Connect-IP: 212.20.242.100 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4482 Lines: 140 3.2.52-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: David Rientjes commit 4b59e6c4730978679b414a8da61514a2518da512 upstream. On large systems with a lot of memory, walking all RAM to determine page types may take a half second or even more. In non-blockable contexts, the page allocator will emit a page allocation failure warning unless __GFP_NOWARN is specified. In such contexts, irqs are typically disabled and such a lengthy delay may even result in NMI watchdog timeouts. To fix this, suppress the page walk in such contexts when printing the page allocation failure warning. Signed-off-by: David Rientjes Cc: Mel Gorman Acked-by: Michal Hocko Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- arch/arm/mm/init.c | 3 +++ arch/ia64/mm/contig.c | 2 ++ arch/ia64/mm/discontig.c | 2 ++ arch/parisc/mm/init.c | 2 ++ arch/unicore32/mm/init.c | 3 +++ include/linux/mm.h | 3 ++- lib/show_mem.c | 3 +++ mm/page_alloc.c | 7 +++++++ 8 files changed, 24 insertions(+), 1 deletion(-) --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -98,6 +98,9 @@ void show_mem(unsigned int filter) printk("Mem-info:\n"); show_free_areas(filter); + if (filter & SHOW_MEM_FILTER_PAGE_COUNT) + return; + for_each_bank (i, mi) { struct membank *bank = &mi->bank[i]; unsigned int pfn1, pfn2; --- a/arch/ia64/mm/contig.c +++ b/arch/ia64/mm/contig.c @@ -46,6 +46,8 @@ void show_mem(unsigned int filter) printk(KERN_INFO "Mem-info:\n"); show_free_areas(filter); printk(KERN_INFO "Node memory in pages:\n"); + if (filter & SHOW_MEM_FILTER_PAGE_COUNT) + return; for_each_online_pgdat(pgdat) { unsigned long present; unsigned long flags; --- a/arch/ia64/mm/discontig.c +++ b/arch/ia64/mm/discontig.c @@ -623,6 +623,8 @@ void show_mem(unsigned int filter) printk(KERN_INFO "Mem-info:\n"); show_free_areas(filter); + if (filter & SHOW_MEM_FILTER_PAGE_COUNT) + return; printk(KERN_INFO "Node memory in pages:\n"); for_each_online_pgdat(pgdat) { unsigned long present; --- a/arch/parisc/mm/init.c +++ b/arch/parisc/mm/init.c @@ -685,6 +685,8 @@ void show_mem(unsigned int filter) printk(KERN_INFO "Mem-info:\n"); show_free_areas(filter); + if (filter & SHOW_MEM_FILTER_PAGE_COUNT) + return; #ifndef CONFIG_DISCONTIGMEM i = max_mapnr; while (i-- > 0) { --- a/arch/unicore32/mm/init.c +++ b/arch/unicore32/mm/init.c @@ -65,6 +65,9 @@ void show_mem(unsigned int filter) printk(KERN_DEFAULT "Mem-info:\n"); show_free_areas(filter); + if (filter & SHOW_MEM_FILTER_PAGE_COUNT) + return; + for_each_bank(i, mi) { struct membank *bank = &mi->bank[i]; unsigned int pfn1, pfn2; --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -865,7 +865,8 @@ extern void pagefault_out_of_memory(void * Flags passed to show_mem() and show_free_areas() to suppress output in * various contexts. */ -#define SHOW_MEM_FILTER_NODES (0x0001u) /* filter disallowed nodes */ +#define SHOW_MEM_FILTER_NODES (0x0001u) /* disallowed nodes */ +#define SHOW_MEM_FILTER_PAGE_COUNT (0x0002u) /* page type count */ extern void show_free_areas(unsigned int flags); extern bool skip_free_areas_node(unsigned int flags, int nid); --- a/lib/show_mem.c +++ b/lib/show_mem.c @@ -18,6 +18,9 @@ void show_mem(unsigned int filter) printk("Mem-Info:\n"); show_free_areas(filter); + if (filter & SHOW_MEM_FILTER_PAGE_COUNT) + return; + for_each_online_pgdat(pgdat) { unsigned long i, flags; --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1760,6 +1760,13 @@ void warn_alloc_failed(gfp_t gfp_mask, i return; /* + * Walking all memory to count page types is very expensive and should + * be inhibited in non-blockable contexts. + */ + if (!(gfp_mask & __GFP_WAIT)) + filter |= SHOW_MEM_FILTER_PAGE_COUNT; + + /* * This documents exceptions given to allocations in certain * contexts that are allowed to allocate outside current's set * of allowed nodes. -- 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/