From 230c92a8797e0e717c6732de0fffdd5726c0f48f Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Fri, 4 Sep 2015 15:47:20 -0700 Subject: [PATCH] userfaultfd: propagate the full address in THP faults The THP faults were not propagating the original fault address. The latest version of the API with uffd.arg.pagefault.address is supposed to propagate the full address through THP faults. This was not a kernel crashing bug and it wouldn't risk to corrupt user memory, but it would cause a SIGBUS failure because the wrong page was being copied. For various reasons this wasn't easily reproducible in the qemu workload, but the strestest exposed the problem immediately. Signed-off-by: Andrea Arcangeli Cc: Pavel Emelyanov Cc: Dave Hansen Cc: Linus Torvalds Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d38aaf9dcba6..279a818a39b1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -717,13 +717,14 @@ static inline pmd_t mk_huge_pmd(struct page *page, pgprot_t prot) static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, - unsigned long haddr, pmd_t *pmd, + unsigned long address, pmd_t *pmd, struct page *page, gfp_t gfp, unsigned int flags) { struct mem_cgroup *memcg; pgtable_t pgtable; spinlock_t *ptl; + unsigned long haddr = address & HPAGE_PMD_MASK; VM_BUG_ON_PAGE(!PageCompound(page), page); @@ -765,7 +766,7 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm, mem_cgroup_cancel_charge(page, memcg); put_page(page); pte_free(mm, pgtable); - ret = handle_userfault(vma, haddr, flags, + ret = handle_userfault(vma, address, flags, VM_UFFD_MISSING); VM_BUG_ON(ret & VM_FAULT_FALLBACK); return ret; @@ -841,7 +842,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, if (pmd_none(*pmd)) { if (userfaultfd_missing(vma)) { spin_unlock(ptl); - ret = handle_userfault(vma, haddr, flags, + ret = handle_userfault(vma, address, flags, VM_UFFD_MISSING); VM_BUG_ON(ret & VM_FAULT_FALLBACK); } else { @@ -865,7 +866,8 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, count_vm_event(THP_FAULT_FALLBACK); return VM_FAULT_FALLBACK; } - return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page, gfp, flags); + return __do_huge_pmd_anonymous_page(mm, vma, address, pmd, page, gfp, + flags); } int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, -- 2.20.1