From b4330afbed0cdceeba33c4945158c55771047e81 Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Fri, 5 Feb 2016 15:36:38 -0800 Subject: mm/hugetlb: fix gigantic page initialization/allocation Attempting to preallocate 1G gigantic huge pages at boot time with "hugepagesz=1G hugepages=1" on the kernel command line will prevent booting with the following: kernel BUG at mm/hugetlb.c:1218! When mapcount accounting was reworked, the setting of compound_mapcount_ptr in prep_compound_gigantic_page was overlooked. As a result, the validation of mapcount in free_huge_page fails. The "BUG_ON" checks in free_huge_page were also changed to "VM_BUG_ON_PAGE" to assist with debugging. Fixes: 53f9263baba69 ("mm: rework mapcount accounting to enable 4k mapping of THPs") Signed-off-by: Mike Kravetz Signed-off-by: Naoya Horiguchi Acked-by: Kirill A. Shutemov Acked-by: David Rientjes Tested-by: Vlastimil Babka Cc: "Aneesh Kumar K.V" Cc: Jerome Marchand Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 12908dcf5831..d7a802427ea8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1214,8 +1214,8 @@ void free_huge_page(struct page *page) set_page_private(page, 0); page->mapping = NULL; - BUG_ON(page_count(page)); - BUG_ON(page_mapcount(page)); + VM_BUG_ON_PAGE(page_count(page), page); + VM_BUG_ON_PAGE(page_mapcount(page), page); restore_reserve = PagePrivate(page); ClearPagePrivate(page); @@ -1286,6 +1286,7 @@ static void prep_compound_gigantic_page(struct page *page, unsigned int order) set_page_count(p, 0); set_compound_head(p, page); } + atomic_set(compound_mapcount_ptr(page), -1); } /* -- cgit v1.2.3 From 080fe2068e1c7f19f565b30b78baf78edf16a980 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Fri, 5 Feb 2016 15:36:41 -0800 Subject: mm, hugetlb: don't require CMA for runtime gigantic pages Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime") has added the runtime gigantic page allocation via alloc_contig_range(), making this support available only when CONFIG_CMA is enabled. Because it doesn't depend on MIGRATE_CMA pageblocks and the associated infrastructure, it is possible with few simple adjustments to require only CONFIG_MEMORY_ISOLATION instead of full CONFIG_CMA. After this patch, alloc_contig_range() and related functions are available and used for gigantic pages with just CONFIG_MEMORY_ISOLATION enabled. Note CONFIG_CMA selects CONFIG_MEMORY_ISOLATION. This allows supporting runtime gigantic pages without the CMA-specific checks in page allocator fastpaths. Signed-off-by: Vlastimil Babka Cc: Luiz Capitulino Cc: Kirill A. Shutemov Cc: Zhang Yanfei Cc: Yasuaki Ishimatsu Cc: Joonsoo Kim Cc: Naoya Horiguchi Cc: Mel Gorman Cc: Davidlohr Bueso Cc: Hillf Danton Cc: Mike Kravetz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index d7a802427ea8..06ae13e869d0 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1001,7 +1001,7 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed) ((node = hstate_next_node_to_free(hs, mask)) || 1); \ nr_nodes--) -#if defined(CONFIG_CMA) && defined(CONFIG_X86_64) +#if defined(CONFIG_X86_64) && ((defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)) static void destroy_compound_gigantic_page(struct page *page, unsigned int order) { -- cgit v1.2.3 From f8b74815a452ff2904b5d7fcce1a5ae2a4d7ca5e Mon Sep 17 00:00:00 2001 From: Vaishali Thakkar Date: Wed, 17 Feb 2016 13:11:26 -0800 Subject: mm/hugetlb.c: fix incorrect proc nr_hugepages value Currently incorrect default hugepage pool size is reported by proc nr_hugepages when number of pages for the default huge page size is specified twice. When multiple huge page sizes are supported, /proc/sys/vm/nr_hugepages indicates the current number of pre-allocated huge pages of the default size. Basically /proc/sys/vm/nr_hugepages displays default_hstate-> max_huge_pages and after boot time pre-allocation, max_huge_pages should equal the number of pre-allocated pages (nr_hugepages). Test case: Note that this is specific to x86 architecture. Boot the kernel with command line option 'default_hugepagesz=1G hugepages=X hugepagesz=2M hugepages=Y hugepagesz=1G hugepages=Z'. After boot, 'cat /proc/sys/vm/nr_hugepages' and 'sysctl -a | grep hugepages' returns the value X. However, dmesg output shows that Z huge pages were pre-allocated. So, the root cause of the problem here is that the global variable default_hstate_max_huge_pages is set if a default huge page size is specified (directly or indirectly) on the command line. After the command line processing in hugetlb_init, if default_hstate_max_huge_pages is set, the value is assigned to default_hstae.max_huge_pages. However, default_hstate.max_huge_pages may have already been set based on the number of pre-allocated huge pages of default_hstate size. The solution to this problem is if hstate->max_huge_pages is already set then it should not set as a result of global max_huge_pages value. Basically if the value of the variable hugepages is set multiple times on a command line for a specific supported hugepagesize then proc layer should consider the last specified value. Signed-off-by: Vaishali Thakkar Reviewed-by: Naoya Horiguchi Cc: Mike Kravetz Cc: Hillf Danton Cc: Kirill A. Shutemov Cc: Dave Hansen Cc: Paul Gortmaker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'mm/hugetlb.c') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 06ae13e869d0..01f2b48c8618 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2630,8 +2630,10 @@ static int __init hugetlb_init(void) hugetlb_add_hstate(HUGETLB_PAGE_ORDER); } default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size)); - if (default_hstate_max_huge_pages) - default_hstate.max_huge_pages = default_hstate_max_huge_pages; + if (default_hstate_max_huge_pages) { + if (!default_hstate.max_huge_pages) + default_hstate.max_huge_pages = default_hstate_max_huge_pages; + } hugetlb_init_hstates(); gather_bootmem_prealloc(); -- cgit v1.2.3