From 3212b535f200c85b5a67cbfaea18431da71b5c72 Mon Sep 17 00:00:00 2001 From: Steve Capper Date: Tue, 23 Apr 2013 12:35:02 +0100 Subject: mm: hugetlb: Copy huge_pmd_share from x86 to mm. Under x86, multiple puds can be made to reference the same bank of huge pmds provided that they represent a full PUD_SIZE of shared huge memory that is aligned to a PUD_SIZE boundary. The code to share pmds does not require any architecture specific knowledge other than the fact that pmds can be indexed, thus can be beneficial to some other architectures. This patch copies the huge pmd sharing (and unsharing) logic from x86/ to mm/ and introduces a new config option to activate it: CONFIG_ARCH_WANTS_HUGE_PMD_SHARE Signed-off-by: Steve Capper Acked-by: Catalin Marinas Acked-by: Andrew Morton --- include/linux/hugetlb.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/hugetlb.h') diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 6b4890fa57e7..981546ad231c 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -69,6 +69,10 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed); int dequeue_hwpoisoned_huge_page(struct page *page); void copy_huge_page(struct page *dst, struct page *src); +#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE +pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud); +#endif + extern unsigned long hugepages_treat_as_movable; extern const unsigned long hugetlb_zero, hugetlb_infinity; extern int sysctl_hugetlb_shm_group; -- cgit v1.2.3 From 13d60f4b6ab5b702dc8d2ee20999f98a93728aec Mon Sep 17 00:00:00 2001 From: Zhang Yi Date: Tue, 25 Jun 2013 21:19:31 +0800 Subject: futex: Take hugepages into account when generating futex_key The futex_keys of process shared futexes are generated from the page offset, the mapping host and the mapping index of the futex user space address. This should result in an unique identifier for each futex. Though this is not true when futexes are located in different subpages of an hugepage. The reason is, that the mapping index for all those futexes evaluates to the index of the base page of the hugetlbfs mapping. So a futex at offset 0 of the hugepage mapping and another one at offset PAGE_SIZE of the same hugepage mapping have identical futex_keys. This happens because the futex code blindly uses page->index. Steps to reproduce the bug: 1. Map a file from hugetlbfs. Initialize pthread_mutex1 at offset 0 and pthread_mutex2 at offset PAGE_SIZE of the hugetlbfs mapping. The mutexes must be initialized as PTHREAD_PROCESS_SHARED because PTHREAD_PROCESS_PRIVATE mutexes are not affected by this issue as their keys solely depend on the user space address. 2. Lock mutex1 and mutex2 3. Create thread1 and in the thread function lock mutex1, which results in thread1 blocking on the locked mutex1. 4. Create thread2 and in the thread function lock mutex2, which results in thread2 blocking on the locked mutex2. 5. Unlock mutex2. Despite the fact that mutex2 got unlocked, thread2 still blocks on mutex2 because the futex_key points to mutex1. To solve this issue we need to take the normal page index of the page which contains the futex into account, if the futex is in an hugetlbfs mapping. In other words, we calculate the normal page mapping index of the subpage in the hugetlbfs mapping. Mappings which are not based on hugetlbfs are not affected and still use page->index. Thanks to Mel Gorman who provided a patch for adding proper evaluation functions to the hugetlbfs code to avoid exposing hugetlbfs specific details to the futex code. [ tglx: Massaged changelog ] Signed-off-by: Zhang Yi Reviewed-by: Jiang Biao Tested-by: Ma Chenggong Reviewed-by: 'Mel Gorman' Acked-by: 'Darren Hart' Cc: 'Peter Zijlstra' Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/000101ce71a6%24a83c5880%24f8b50980%24@com Signed-off-by: Thomas Gleixner --- include/linux/hugetlb.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'include/linux/hugetlb.h') diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 6b4890fa57e7..feaf0c7fb7d8 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -358,6 +358,17 @@ static inline int hstate_index(struct hstate *h) return h - hstates; } +pgoff_t __basepage_index(struct page *page); + +/* Return page->index in PAGE_SIZE units */ +static inline pgoff_t basepage_index(struct page *page) +{ + if (!PageCompound(page)) + return page->index; + + return __basepage_index(page); +} + #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; #define alloc_huge_page_node(h, nid) NULL @@ -378,6 +389,11 @@ static inline unsigned int pages_per_huge_page(struct hstate *h) } #define hstate_index_to_shift(index) 0 #define hstate_index(h) 0 + +static inline pgoff_t basepage_index(struct page *page) +{ + return page->index; +} #endif /* CONFIG_HUGETLB_PAGE */ #endif /* _LINUX_HUGETLB_H */ -- cgit v1.2.3 From 5f1e31d2f5977d910d0b2f5018173e99241d1940 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Wed, 3 Jul 2013 15:02:42 -0700 Subject: mm/hugetlb: remove hugetlb_prefault hugetlb_prefault() is not used any more, this patch removes it. Signed-off-by: Wanpeng Li Reviewed-by: Michal Hocko Cc: KAMEZAWA Hiroyuki Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/hugetlb.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux/hugetlb.h') diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 89d4fbf681e7..c2b1801a160b 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -55,7 +55,6 @@ void __unmap_hugepage_range_final(struct mmu_gather *tlb, void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma, unsigned long start, unsigned long end, struct page *ref_page); -int hugetlb_prefault(struct address_space *, struct vm_area_struct *); void hugetlb_report_meminfo(struct seq_file *); int hugetlb_report_node_meminfo(int, char *); void hugetlb_show_meminfo(void); @@ -114,7 +113,6 @@ static inline unsigned long hugetlb_total_pages(void) #define follow_hugetlb_page(m,v,p,vs,a,b,i,w) ({ BUG(); 0; }) #define follow_huge_addr(mm, addr, write) ERR_PTR(-EINVAL) #define copy_hugetlb_page_range(src, dst, vma) ({ BUG(); 0; }) -#define hugetlb_prefault(mapping, vma) ({ BUG(); 0; }) static inline void hugetlb_report_meminfo(struct seq_file *m) { } -- cgit v1.2.3