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980ac1672e
Until now, if some page_ext users want to use it's own field on
page_ext, it should be defined in struct page_ext by hard-coding. It
has a problem that wastes memory in following situation.
struct page_ext {
#ifdef CONFIG_A
int a;
#endif
#ifdef CONFIG_B
int b;
#endif
};
Assume that kernel is built with both CONFIG_A and CONFIG_B. Even if we
enable feature A and doesn't enable feature B at runtime, each entry of
struct page_ext takes two int rather than one int. It's undesirable
result so this patch tries to fix it.
To solve above problem, this patch implements to support extra space
allocation at runtime. When need() callback returns true, it's extra
memory requirement is summed to entry size of page_ext. Also, offset
for each user's extra memory space is returned. With this offset, user
can use this extra space and there is no need to define needed field on
page_ext by hard-coding.
This patch only implements an infrastructure. Following patch will use
it for page_owner which is only user having it's own fields on page_ext.
Link: http://lkml.kernel.org/r/1471315879-32294-6-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
91 lines
2 KiB
C
91 lines
2 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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size_t offset;
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size_t size;
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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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