Changelog since v2 o Change some function names o Remove mark_memmap_hole in memmap bring up o Change CONFIG_SPARSEMEM with CONFIG_ARCH_HAS_HOLES_MEMORYMODEL I have a plan following as after this patch is acked. TODO: 1) expand pfn_valid to FALTMEM in ARM I think we can enhance pfn_valid of FLATMEM in ARM. Now it is doing binary search and it's expesive. First of all, After we merge this patch, I expand it to FALTMEM of ARM. 2) remove memmap_valid_within We can remove memmap_valid_within by strict pfn_valid's tight check. 3) Optimize hole check in sparsemem In case of spasemem, we can optimize pfn_valid through defining new flag like SECTION_HAS_HOLE of hole mem_section. == CUT HERE == Kukjin reported oops happen while he change min_free_kbytes http://www.spinics.net/lists/arm-kernel/msg92894.html It happen by memory map on sparsemem. The system has a memory map following as. section 0 section 1 section 2 0x20000000-0x25000000, 0x40000000-0x50000000, 0x50000000-0x58000000 SECTION_SIZE_BITS 28(256M) It means section 0 is an incompletely filled section. Nontheless, current pfn_valid of sparsemem checks pfn loosely. It checks only mem_section's validation but ARM can free mem_map on hole to save memory space. So in above case, pfn on 0x25000000 can pass pfn_valid's validation check. It's not what we want. We can match section size to smallest valid size.(ex, above case, 16M) But Russell doesn't like it due to mem_section's memory overhead with different configuration(ex, 512K section). I tried to add valid pfn range in mem_section but everyone doesn't like it due to size overhead. This patch is suggested by KAMEZAWA-san. I just fixed compile error and change some naming. This patch registers address of mem_section to memmap itself's page struct's pg->private field. This means the page is used for memmap of the section. Otherwise, the page is used for other purpose and memmap has a hole. This patch is based on mmotm-2010-07-19 Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Reported-by: Kukjin Kim <kgene.kim@xxxxxxxxxxx> Cc: Mel Gorman <mel@xxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxxx> --- arch/arm/mm/init.c | 4 +++- include/linux/mmzone.h | 22 +++++++++++++++++++++- mm/mmzone.c | 34 ++++++++++++++++++++++++++++++++++ 5 files changed, 58 insertions(+), 2 deletions(-) diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index f6a9994..25e2670 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -482,8 +482,10 @@ free_memmap(int node, unsigned long start_pfn, unsigned long end_pfn) * If there are free pages between these, * free the section of the memmap array. */ - if (pg < pgend) + if (pg < pgend) { + mark_invalid_memmap(pg >> PAGE_SHIFT, pgend >> PAGE_SHIFT); free_bootmem_node(NODE_DATA(node), pg, pgend - pg); + } } /* diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index b4d109e..a3195bd 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -15,6 +15,7 @@ #include <linux/seqlock.h> #include <linux/nodemask.h> #include <linux/pageblock-flags.h> +#include <linux/mm_types.h> #include <generated/bounds.h> #include <asm/atomic.h> #include <asm/page.h> @@ -1049,11 +1050,30 @@ static inline struct mem_section *__pfn_to_section(unsigned long pfn) return __nr_to_section(pfn_to_section_nr(pfn)); } +void mark_invalid_memmap(unsigned long start, unsigned long end); + +#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL +#define MEMMAP_HOLE (0x1UL) +static inline int memmap_valid(unsigned long pfn) +{ + struct page *page = pfn_to_page(pfn); + struct page *__pg = virt_to_page(page); + return !(__pg->private & MEMMAP_HOLE); +} +#else +static inline int memmap_valid(unsigned long pfn) +{ + return 1; +} +#endif + static inline int pfn_valid(unsigned long pfn) { + struct mem_section *ms; if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; - return valid_section(__nr_to_section(pfn_to_section_nr(pfn))); + ms = __nr_to_section(pfn_to_section_nr(pfn)); + return valid_section(ms) && memmap_valid(pfn); } static inline int pfn_present(unsigned long pfn) diff --git a/mm/mmzone.c b/mm/mmzone.c index f5b7d17..7c84e5e 100644 --- a/mm/mmzone.c +++ b/mm/mmzone.c @@ -86,4 +86,38 @@ int memmap_valid_within(unsigned long pfn, return 1; } + +/* + * Fill pg->private on hole memmap with MEMMAP_HOLE. + * pfn_valid() will check this later. (see include/linux/mmzone.h) + * Evenry arch should call + * mark_invalid_memmap(start, end) # for all holes in mem_map. + * please see usage in ARM. + */ +void mark_invalid_memmap(unsigned long start, unsigned long end) +{ + struct mem_section *ms; + unsigned long pos, next; + struct page *pg; + void *memmap, *mapend; + + for (pos = start; pos < end; pos = next) { + next = (pos + PAGES_PER_SECTION) & PAGE_SECTION_MASK; + ms = __pfn_to_section(pos); + if (!valid_section(ms)) + continue; + + for (memmap = (void*)pfn_to_page(pos), + /* The last page in section */ + mapend = pfn_to_page(next-1); + memmap < mapend; memmap += PAGE_SIZE) { + pg = virt_to_page(memmap); + pg->private = MEMMAP_HOLE; + } + } +} +#else +void mark_invalid_memmap(unsigned long start, unsigned long end) +{ +} #endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */ -- 1.7.0.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . 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