f2ca0b5571
Currently, we store each page's allocation stacktrace on corresponding page_ext structure and it requires a lot of memory. This causes the problem that memory tight system doesn't work well if page_owner is enabled. Moreover, even with this large memory consumption, we cannot get full stacktrace because we allocate memory at boot time and just maintain 8 stacktrace slots to balance memory consumption. We could increase it to more but it would make system unusable or change system behaviour. To solve the problem, this patch uses stackdepot to store stacktrace. It obviously provides memory saving but there is a drawback that stackdepot could fail. stackdepot allocates memory at runtime so it could fail if system has not enough memory. But, most of allocation stack are generated at very early time and there are much memory at this time. So, failure would not happen easily. And, one failure means that we miss just one page's allocation stacktrace so it would not be a big problem. In this patch, when memory allocation failure happens, we store special stracktrace handle to the page that is failed to save stacktrace. With it, user can guess memory usage properly even if failure happens. Memory saving looks as following. (4GB memory system with page_owner) (before the patch -> after the patch) static allocation: 92274688 bytes -> 25165824 bytes dynamic allocation after boot + kernel build: 0 bytes -> 327680 bytes total: 92274688 bytes -> 25493504 bytes 72% reduction in total. Note that implementation looks complex than someone would imagine because there is recursion issue. stackdepot uses page allocator and page_owner is called at page allocation. Using stackdepot in page_owner could re-call page allcator and then page_owner. That is a recursion. To detect and avoid it, whenever we obtain stacktrace, recursion is checked and page_owner is set to dummy information if found. Dummy information means that this page is allocated for page_owner feature itself (such as stackdepot) and it's understandable behavior for user. [iamjoonsoo.kim@lge.com: mm-page_owner-use-stackdepot-to-store-stacktrace-v3] Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com Link: http://lkml.kernel.org/r/1466150259-27727-7-git-send-email-iamjoonsoo.kim@lge.com Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Minchan Kim <minchan@kernel.org> Cc: Alexander Potapenko <glider@google.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
90 lines
1.9 KiB
C
90 lines
1.9 KiB
C
#ifndef __LINUX_PAGE_EXT_H
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#define __LINUX_PAGE_EXT_H
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#include <linux/types.h>
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#include <linux/stacktrace.h>
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#include <linux/stackdepot.h>
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struct pglist_data;
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struct page_ext_operations {
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bool (*need)(void);
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void (*init)(void);
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};
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#ifdef CONFIG_PAGE_EXTENSION
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/*
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* page_ext->flags bits:
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*
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* PAGE_EXT_DEBUG_POISON is set for poisoned pages. This is used to
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* implement generic debug pagealloc feature. The pages are filled with
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* poison patterns and set this flag after free_pages(). The poisoned
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* pages are verified whether the patterns are not corrupted and clear
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* the flag before alloc_pages().
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*/
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enum page_ext_flags {
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PAGE_EXT_DEBUG_POISON, /* Page is poisoned */
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PAGE_EXT_DEBUG_GUARD,
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PAGE_EXT_OWNER,
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#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
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PAGE_EXT_YOUNG,
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PAGE_EXT_IDLE,
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#endif
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};
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/*
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* Page Extension can be considered as an extended mem_map.
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* A page_ext page is associated with every page descriptor. The
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* page_ext helps us add more information about the page.
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* All page_ext are allocated at boot or memory hotplug event,
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* then the page_ext for pfn always exists.
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*/
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struct page_ext {
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unsigned long flags;
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#ifdef CONFIG_PAGE_OWNER
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unsigned int order;
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gfp_t gfp_mask;
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int last_migrate_reason;
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depot_stack_handle_t handle;
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#endif
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};
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extern void pgdat_page_ext_init(struct pglist_data *pgdat);
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#ifdef CONFIG_SPARSEMEM
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static inline void page_ext_init_flatmem(void)
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{
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}
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extern void page_ext_init(void);
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#else
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extern void page_ext_init_flatmem(void);
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static inline void page_ext_init(void)
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{
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}
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#endif
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struct page_ext *lookup_page_ext(struct page *page);
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#else /* !CONFIG_PAGE_EXTENSION */
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struct page_ext;
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static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
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{
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}
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static inline struct page_ext *lookup_page_ext(struct page *page)
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{
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return NULL;
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}
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static inline void page_ext_init(void)
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{
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}
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static inline void page_ext_init_flatmem(void)
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{
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}
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#endif /* CONFIG_PAGE_EXTENSION */
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#endif /* __LINUX_PAGE_EXT_H */
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