Messages in this thread | | | Date | Mon, 13 Jul 2015 17:45:46 +0900 | From | Gioh Kim <> | Subject | Re: [RFCv3 2/5] mm/compaction: enable mobile-page migration |
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>> @@ -51,6 +54,66 @@ extern void compaction_defer_reset(struct zone *zone, int order, >> bool alloc_success); >> extern bool compaction_restarting(struct zone *zone, int order); >> >> +static inline bool mobile_page(struct page *page) >> +{ >> + return page->mapping && page->mapping->a_ops && > > Dereferncing mapping->a_ops isn't safe without page-lock and isn't required: > all mappings always have ->a_ops. >
I got it.
>> +static inline void putback_mobilepage(struct page *page) >> +{ >> + /* >> + * 'lock_page()' stabilizes the page and prevents races against >> + * concurrent isolation threads attempting to re-isolate it. >> + */ >> + lock_page(page); >> + if (mobile_page(page) && page->mapping->a_ops->putbackpage) { > > It seems "if (page->mapping && page->mapping->a_ops->putbackpage)" > should be enough: we already seen that page as mobile.
Ditto.
> >> + page->mapping->a_ops->putbackpage(page); >> + /* drop the extra ref count taken for mobile page isolation */ >> + put_page(page); >> + } >> + unlock_page(page); > > call put_page() after unlock and do that always -- putback must drop > page reference from caller. > > lock_page(page); > if (page->mapping && page->mapping->a_ops->putbackpage) > page->mapping->a_ops->putbackpage(page); > unlock_page(); > put_page(page); >
Ditto.
>> +} >> #else >> static inline unsigned long try_to_compact_pages(gfp_t gfp_mask, >> unsigned int order, int alloc_flags, >> @@ -83,6 +146,19 @@ static inline bool compaction_deferred(struct zone *zone, int order) >> return true; >> } >> >> +static inline bool mobile_page(struct page *page) >> +{ >> + return false; >> +} >> + >> +static inline bool isolate_mobilepage(struct page *page, isolate_mode_t mode) >> +{ >> + return false; >> +} >> + >> +static inline void putback_mobilepage(struct page *page) >> +{ >> +} >> #endif /* CONFIG_COMPACTION */ >> >> #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA) >> diff --git a/include/linux/fs.h b/include/linux/fs.h >> index 35ec87e..33c9aa5 100644 >> --- a/include/linux/fs.h >> +++ b/include/linux/fs.h >> @@ -395,6 +395,8 @@ struct address_space_operations { >> */ >> int (*migratepage) (struct address_space *, >> struct page *, struct page *, enum migrate_mode); >> + bool (*isolatepage) (struct page *, isolate_mode_t); >> + void (*putbackpage) (struct page *); >> int (*launder_page) (struct page *); >> int (*is_partially_uptodate) (struct page *, unsigned long, >> unsigned long); >> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h >> index f34e040..abef145 100644 >> --- a/include/linux/page-flags.h >> +++ b/include/linux/page-flags.h >> @@ -582,6 +582,25 @@ static inline void __ClearPageBalloon(struct page *page) >> atomic_set(&page->_mapcount, -1); >> } >> >> +#define PAGE_MOBILE_MAPCOUNT_VALUE (-255) >> + >> +static inline int PageMobile(struct page *page) >> +{ >> + return atomic_read(&page->_mapcount) == PAGE_MOBILE_MAPCOUNT_VALUE; >> +} >> + >> +static inline void __SetPageMobile(struct page *page) >> +{ >> + VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page); >> + atomic_set(&page->_mapcount, PAGE_MOBILE_MAPCOUNT_VALUE); >> +} >> + >> +static inline void __ClearPageMobile(struct page *page) >> +{ >> + VM_BUG_ON_PAGE(!PageMobile(page), page); >> + atomic_set(&page->_mapcount, -1); >> +} >> + >> /* >> * If network-based swap is enabled, sl*b must keep track of whether pages >> * were allocated from pfmemalloc reserves. >> diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h >> index a6c4962..d50d9e8 100644 >> --- a/include/uapi/linux/kernel-page-flags.h >> +++ b/include/uapi/linux/kernel-page-flags.h >> @@ -33,6 +33,7 @@ >> #define KPF_THP 22 >> #define KPF_BALLOON 23 >> #define KPF_ZERO_PAGE 24 >> +#define KPF_MOBILE 25 >> >> >> #endif /* _UAPILINUX_KERNEL_PAGE_FLAGS_H */ >> -- >> 2.1.4 >> >
I fixed the code as your comments and I found patch 3/5 and 4/5 could not be applied separately. So I merge them and report new [PATCH]. I appreciate your reviews.
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