From 4db9b2efe94967be34e3b136a93251a3c1736dd5 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Mon, 10 Jul 2017 15:48:44 -0700 Subject: [PATCH] hugetlb, memory_hotplug: prefer to use reserved pages for migration new_node_page will try to use the origin's next NUMA node as the migration destination for hugetlb pages. If such a node doesn't have any preallocated pool it falls back to __alloc_buddy_huge_page_no_mpol to allocate a surplus page instead. This is quite subotpimal for any configuration when hugetlb pages are no distributed to all NUMA nodes evenly. Say we have a hotplugable node 4 and spare hugetlb pages are node 0 /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node3/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node4/hugepages/hugepages-2048kB/nr_hugepages:10000 /sys/devices/system/node/node5/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node6/hugepages/hugepages-2048kB/nr_hugepages:0 /sys/devices/system/node/node7/hugepages/hugepages-2048kB/nr_hugepages:0 Now we consume the whole pool on node 4 and try to offline this node. All the allocated pages should be moved to node0 which has enough preallocated pages to hold them. With the current implementation offlining very likely fails because hugetlb allocations during runtime are much less reliable. Fix this by reusing the nodemask which excludes migration source and try to find a first node which has a page in the preallocated pool first and fall back to __alloc_buddy_huge_page_no_mpol only when the whole pool is consumed. [akpm@linux-foundation.org: remove bogus arg from alloc_huge_page_nodemask() stub] Link: http://lkml.kernel.org/r/20170608074553.22152-3-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Vlastimil Babka Cc: Naoya Horiguchi Cc: Xishi Qiu Cc: zhong jiang Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/hugetlb.h | 2 ++ mm/hugetlb.c | 27 +++++++++++++++++++++++++++ mm/memory_hotplug.c | 9 ++------- 3 files changed, 31 insertions(+), 7 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 57f700ac127e..8fd0725d3f30 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -349,6 +349,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, 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); +struct page *alloc_huge_page_nodemask(struct hstate *h, const nodemask_t *nmask); int huge_add_to_page_cache(struct page *page, struct address_space *mapping, pgoff_t idx); @@ -524,6 +525,7 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr struct hstate {}; #define alloc_huge_page(v, a, r) NULL #define alloc_huge_page_node(h, nid) NULL +#define alloc_huge_page_nodemask(h, nmask) NULL #define alloc_huge_page_noerr(v, a, r) NULL #define alloc_bootmem_huge_page(h) NULL #define hstate_file(f) NULL diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 761a669d0b62..01c11ceb47d6 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1723,6 +1723,33 @@ struct page *alloc_huge_page_node(struct hstate *h, int nid) return page; } +struct page *alloc_huge_page_nodemask(struct hstate *h, const nodemask_t *nmask) +{ + struct page *page = NULL; + int node; + + spin_lock(&hugetlb_lock); + if (h->free_huge_pages - h->resv_huge_pages > 0) { + for_each_node_mask(node, *nmask) { + page = dequeue_huge_page_node_exact(h, node); + if (page) + break; + } + } + spin_unlock(&hugetlb_lock); + if (page) + return page; + + /* No reservations, try to overcommit */ + for_each_node_mask(node, *nmask) { + page = __alloc_buddy_huge_page_no_mpol(h, node); + if (page) + return page; + } + + return NULL; +} + /* * Increase the hugetlb pool such that it can accommodate a reservation * of size 'delta'. diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index f42a8ef93ec4..1cf3404bd065 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1446,14 +1446,9 @@ static struct page *new_node_page(struct page *page, unsigned long private, if (nodes_empty(nmask)) node_set(nid, nmask); - /* - * TODO: allocate a destination hugepage from a nearest neighbor node, - * accordance with memory policy of the user process if possible. For - * now as a simple work-around, we use the next node for destination. - */ if (PageHuge(page)) - return alloc_huge_page_node(page_hstate(compound_head(page)), - next_node_in(nid, nmask)); + return alloc_huge_page_nodemask( + page_hstate(compound_head(page)), &nmask); if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))