Though migrating gigantic HugeTLB pages does not sound much like real world use case, they can be affected by memory errors. Hence migration at the PGD level HugeTLB pages should be supported just to enable soft and hard offline use cases. While allocating the new gigantic HugeTLB page, it should not matter whether new page comes from the same node or not. There would be very few gigantic pages on the system afterall, we should not be bothered about node locality when trying to save a big page from crashing. This introduces a new HugeTLB allocator called alloc_huge_page_nonid() which will scan over all online nodes on the system and allocate a single HugeTLB page. Signed-off-by: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx> --- Tested on a POWER8 machine with 16GB pages along with Aneesh's recent HugeTLB enablement patch series on powerpc which can be found here. https://lkml.org/lkml/2017/4/17/225 Here, we directly call alloc_huge_page_nonid() which ignores the node locality. But we can also first call normal alloc_huge_page() with the node number and if that fails to allocate only then call alloc_huge_page_nonid() as a fallback option. Aneesh mentioned about the waste of memory if we just have to soft offline a single page. The problem persists both on PGD as well as PMD level HugeTLB pages. Tried solving the problem with https://patchwork.kernel.org/patch/9690119/ but right now madvise splits the entire range of HugeTLB pages (if the page is HugeTLB one) and calls soft_offline_page() on the head page of each HugeTLB page as soft_offline_page() acts on the entire HugeTLB range not just the individual pages. Changing the iterator in madvise() scan over individual pages solves the problem but then it creates multiple HugeTLB migrations (HUGE_PAGE_SIZE / PAGE_SIZE times to be precise) if we really have to soft offline a single HugeTLB page which is not optimal. Hence for now, lets just enable PGD level HugeTLB soft offline at par with the PMD level HugeTLB before we can go back and address the memory wastage problem comprehensively for both PGD and PMD level HugeTLB page as mentioned above. include/linux/hugetlb.h | 8 +++++++- mm/hugetlb.c | 17 +++++++++++++++++ mm/memory-failure.c | 8 ++++++-- 3 files changed, 30 insertions(+), 3 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 04b73a9c8b4b..882e6241da71 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -347,6 +347,7 @@ struct huge_bootmem_page { struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr, int avoid_reserve); +struct page *alloc_huge_page_nonid(struct hstate *h); struct page *alloc_huge_page_node(struct hstate *h, int nid); struct page *alloc_huge_page_noerr(struct vm_area_struct *vma, unsigned long addr, int avoid_reserve); @@ -473,7 +474,11 @@ extern int dissolve_free_huge_pages(unsigned long start_pfn, static inline bool hugepage_migration_supported(struct hstate *h) { #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION - return huge_page_shift(h) == PMD_SHIFT; + if ((huge_page_shift(h) == PMD_SHIFT) || + (huge_page_shift(h) == PGDIR_SHIFT)) + return true; + else + return false; #else return false; #endif @@ -511,6 +516,7 @@ static inline void hugetlb_count_sub(long l, struct mm_struct *mm) #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; #define alloc_huge_page(v, a, r) NULL +#define alloc_huge_page_nonid(h) NULL #define alloc_huge_page_node(h, nid) NULL #define alloc_huge_page_noerr(v, a, r) NULL #define alloc_bootmem_huge_page(h) NULL diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 97a44db06850..bd96fff2bc09 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1669,6 +1669,23 @@ struct page *__alloc_buddy_huge_page_with_mpol(struct hstate *h, return __alloc_buddy_huge_page(h, vma, addr, NUMA_NO_NODE); } +struct page *alloc_huge_page_nonid(struct hstate *h) +{ + struct page *page = NULL; + int nid = 0; + + spin_lock(&hugetlb_lock); + if (h->free_huge_pages - h->resv_huge_pages > 0) { + for_each_online_node(nid) { + page = dequeue_huge_page_node(h, nid); + if (page) + break; + } + } + spin_unlock(&hugetlb_lock); + return page; +} + /* * This allocation function is useful in the context where vma is irrelevant. * E.g. soft-offlining uses this function because it only cares physical diff --git a/mm/memory-failure.c b/mm/memory-failure.c index fe64d7729a8e..d4f5710cf3f7 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1481,11 +1481,15 @@ EXPORT_SYMBOL(unpoison_memory); static struct page *new_page(struct page *p, unsigned long private, int **x) { int nid = page_to_nid(p); - if (PageHuge(p)) + if (PageHuge(p)) { + if (hstate_is_gigantic(page_hstate(compound_head(p)))) + return alloc_huge_page_nonid(page_hstate(compound_head(p))); + return alloc_huge_page_node(page_hstate(compound_head(p)), nid); - else + } else { return __alloc_pages_node(nid, GFP_HIGHUSER_MOVABLE, 0); + } } /* -- 2.12.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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