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![Naoya Horiguchi](/assets/img/avatar_default.png)
Until now we can't offline memory blocks which contain hugepages because a hugepage is considered as an unmovable page. But now with this patch series, a hugepage has become movable, so by using hugepage migration we can offline such memory blocks. What's different from other users of hugepage migration is that we need to decompose all the hugepages inside the target memory block into free buddy pages after hugepage migration, because otherwise free hugepages remaining in the memory block intervene the memory offlining. For this reason we introduce new functions dissolve_free_huge_page() and dissolve_free_huge_pages(). Other than that, what this patch does is straightforwardly to add hugepage migration code, that is, adding hugepage code to the functions which scan over pfn and collect hugepages to be migrated, and adding a hugepage allocation function to alloc_migrate_target(). As for larger hugepages (1GB for x86_64), it's not easy to do hotremove over them because it's larger than memory block. So we now simply leave it to fail as it is. [yongjun_wei@trendmicro.com.cn: remove duplicated include] Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Andi Kleen <ak@linux.intel.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rik van Riel <riel@redhat.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
273 lines
7.5 KiB
C
273 lines
7.5 KiB
C
/*
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* linux/mm/page_isolation.c
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*/
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#include <linux/mm.h>
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#include <linux/page-isolation.h>
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#include <linux/pageblock-flags.h>
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#include <linux/memory.h>
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#include <linux/hugetlb.h>
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#include "internal.h"
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int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
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{
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struct zone *zone;
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unsigned long flags, pfn;
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struct memory_isolate_notify arg;
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int notifier_ret;
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int ret = -EBUSY;
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zone = page_zone(page);
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spin_lock_irqsave(&zone->lock, flags);
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pfn = page_to_pfn(page);
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arg.start_pfn = pfn;
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arg.nr_pages = pageblock_nr_pages;
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arg.pages_found = 0;
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/*
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* It may be possible to isolate a pageblock even if the
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* migratetype is not MIGRATE_MOVABLE. The memory isolation
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* notifier chain is used by balloon drivers to return the
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* number of pages in a range that are held by the balloon
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* driver to shrink memory. If all the pages are accounted for
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* by balloons, are free, or on the LRU, isolation can continue.
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* Later, for example, when memory hotplug notifier runs, these
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* pages reported as "can be isolated" should be isolated(freed)
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* by the balloon driver through the memory notifier chain.
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*/
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notifier_ret = memory_isolate_notify(MEM_ISOLATE_COUNT, &arg);
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notifier_ret = notifier_to_errno(notifier_ret);
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if (notifier_ret)
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goto out;
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/*
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* FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
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* We just check MOVABLE pages.
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*/
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if (!has_unmovable_pages(zone, page, arg.pages_found,
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skip_hwpoisoned_pages))
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ret = 0;
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/*
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* immobile means "not-on-lru" paes. If immobile is larger than
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* removable-by-driver pages reported by notifier, we'll fail.
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*/
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out:
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if (!ret) {
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unsigned long nr_pages;
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int migratetype = get_pageblock_migratetype(page);
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set_pageblock_migratetype(page, MIGRATE_ISOLATE);
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nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);
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__mod_zone_freepage_state(zone, -nr_pages, migratetype);
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}
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spin_unlock_irqrestore(&zone->lock, flags);
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if (!ret)
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drain_all_pages();
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return ret;
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}
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void unset_migratetype_isolate(struct page *page, unsigned migratetype)
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{
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struct zone *zone;
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unsigned long flags, nr_pages;
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zone = page_zone(page);
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spin_lock_irqsave(&zone->lock, flags);
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if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
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goto out;
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nr_pages = move_freepages_block(zone, page, migratetype);
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__mod_zone_freepage_state(zone, nr_pages, migratetype);
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set_pageblock_migratetype(page, migratetype);
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out:
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spin_unlock_irqrestore(&zone->lock, flags);
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}
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static inline struct page *
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__first_valid_page(unsigned long pfn, unsigned long nr_pages)
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{
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int i;
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for (i = 0; i < nr_pages; i++)
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if (pfn_valid_within(pfn + i))
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break;
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if (unlikely(i == nr_pages))
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return NULL;
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return pfn_to_page(pfn + i);
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}
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/*
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* start_isolate_page_range() -- make page-allocation-type of range of pages
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* to be MIGRATE_ISOLATE.
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* @start_pfn: The lower PFN of the range to be isolated.
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* @end_pfn: The upper PFN of the range to be isolated.
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* @migratetype: migrate type to set in error recovery.
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*
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* Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
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* the range will never be allocated. Any free pages and pages freed in the
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* future will not be allocated again.
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*
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* start_pfn/end_pfn must be aligned to pageblock_order.
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* Returns 0 on success and -EBUSY if any part of range cannot be isolated.
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*/
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int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
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unsigned migratetype, bool skip_hwpoisoned_pages)
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{
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unsigned long pfn;
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unsigned long undo_pfn;
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struct page *page;
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BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
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BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
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for (pfn = start_pfn;
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pfn < end_pfn;
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pfn += pageblock_nr_pages) {
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page = __first_valid_page(pfn, pageblock_nr_pages);
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if (page &&
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set_migratetype_isolate(page, skip_hwpoisoned_pages)) {
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undo_pfn = pfn;
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goto undo;
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}
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}
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return 0;
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undo:
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for (pfn = start_pfn;
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pfn < undo_pfn;
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pfn += pageblock_nr_pages)
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unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
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return -EBUSY;
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}
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/*
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* Make isolated pages available again.
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*/
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int undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
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unsigned migratetype)
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{
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unsigned long pfn;
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struct page *page;
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BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
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BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
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for (pfn = start_pfn;
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pfn < end_pfn;
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pfn += pageblock_nr_pages) {
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page = __first_valid_page(pfn, pageblock_nr_pages);
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if (!page || get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
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continue;
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unset_migratetype_isolate(page, migratetype);
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}
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return 0;
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}
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/*
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* Test all pages in the range is free(means isolated) or not.
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* all pages in [start_pfn...end_pfn) must be in the same zone.
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* zone->lock must be held before call this.
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*
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* Returns 1 if all pages in the range are isolated.
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*/
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static int
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__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
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bool skip_hwpoisoned_pages)
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{
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struct page *page;
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while (pfn < end_pfn) {
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if (!pfn_valid_within(pfn)) {
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pfn++;
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continue;
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}
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page = pfn_to_page(pfn);
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if (PageBuddy(page)) {
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/*
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* If race between isolatation and allocation happens,
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* some free pages could be in MIGRATE_MOVABLE list
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* although pageblock's migratation type of the page
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* is MIGRATE_ISOLATE. Catch it and move the page into
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* MIGRATE_ISOLATE list.
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*/
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if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) {
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struct page *end_page;
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end_page = page + (1 << page_order(page)) - 1;
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move_freepages(page_zone(page), page, end_page,
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MIGRATE_ISOLATE);
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}
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pfn += 1 << page_order(page);
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}
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else if (page_count(page) == 0 &&
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get_freepage_migratetype(page) == MIGRATE_ISOLATE)
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pfn += 1;
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else if (skip_hwpoisoned_pages && PageHWPoison(page)) {
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/*
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* The HWPoisoned page may be not in buddy
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* system, and page_count() is not 0.
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*/
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pfn++;
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continue;
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}
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else
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break;
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}
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if (pfn < end_pfn)
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return 0;
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return 1;
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}
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int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
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bool skip_hwpoisoned_pages)
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{
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unsigned long pfn, flags;
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struct page *page;
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struct zone *zone;
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int ret;
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/*
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* Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
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* are not aligned to pageblock_nr_pages.
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* Then we just check migratetype first.
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*/
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for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
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page = __first_valid_page(pfn, pageblock_nr_pages);
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if (page && get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
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break;
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}
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page = __first_valid_page(start_pfn, end_pfn - start_pfn);
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if ((pfn < end_pfn) || !page)
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return -EBUSY;
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/* Check all pages are free or marked as ISOLATED */
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zone = page_zone(page);
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spin_lock_irqsave(&zone->lock, flags);
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ret = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
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skip_hwpoisoned_pages);
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spin_unlock_irqrestore(&zone->lock, flags);
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return ret ? 0 : -EBUSY;
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}
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struct page *alloc_migrate_target(struct page *page, unsigned long private,
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int **resultp)
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{
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gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;
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/*
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* TODO: allocate a destination hugepage from a nearest neighbor node,
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* accordance with memory policy of the user process if possible. For
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* now as a simple work-around, we use the next node for destination.
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*/
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if (PageHuge(page)) {
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nodemask_t src = nodemask_of_node(page_to_nid(page));
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nodemask_t dst;
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nodes_complement(dst, src);
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return alloc_huge_page_node(page_hstate(compound_head(page)),
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next_node(page_to_nid(page), dst));
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}
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if (PageHighMem(page))
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gfp_mask |= __GFP_HIGHMEM;
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return alloc_page(gfp_mask);
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}
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