From d63fa776c1560c8cdc67352bdbe10543e8b13d75 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Wed, 27 Mar 2013 10:24:17 +1100 Subject: [PATCH] mm, show_mem: suppress page counts in non-blockable contexts 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 --- 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(-) diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index ad722f1208a5..ad9a9f3f0322 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -99,6 +99,9 @@ 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; diff --git a/arch/ia64/mm/contig.c b/arch/ia64/mm/contig.c index 80dab509dfb0..67c59ebec899 100644 --- a/arch/ia64/mm/contig.c +++ b/arch/ia64/mm/contig.c @@ -47,6 +47,8 @@ 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; diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c index c2e955ee79a8..a57436e5d405 100644 --- 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; diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c index 3ac462de53a4..cf2da13c41e6 100644 --- a/arch/parisc/mm/init.c +++ b/arch/parisc/mm/init.c @@ -697,6 +697,8 @@ 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) { diff --git a/arch/unicore32/mm/init.c b/arch/unicore32/mm/init.c index de186bde8975..644482882bae 100644 --- a/arch/unicore32/mm/init.c +++ b/arch/unicore32/mm/init.c @@ -66,6 +66,9 @@ 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; diff --git a/include/linux/mm.h b/include/linux/mm.h index acb2c98a4e3f..92162a59b336 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -899,7 +899,8 @@ 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); diff --git a/lib/show_mem.c b/lib/show_mem.c index 4407f8c9b1f7..b7c72311ad0c 100644 --- 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; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7ff1536f01b8..da7a2fe7332e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2002,6 +2002,13 @@ void warn_alloc_failed(gfp_t gfp_mask, int order, const char *fmt, ...) debug_guardpage_minorder() > 0) 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 -- 2.39.5