From 810a56b943e265bbabfcd5a8e54cb8d3b16cd6e4 Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Wed, 22 Feb 2017 15:42:58 -0800 Subject: userfaultfd: hugetlbfs: fix __mcopy_atomic_hugetlb retry/error processing The new routine copy_huge_page_from_user() uses kmap_atomic() to map PAGE_SIZE pages. However, this prevents page faults in the subsequent call to copy_from_user(). This is OK in the case where the routine is copied with mmap_sema held. However, in another case we want to allow page faults. So, add a new argument allow_pagefault to indicate if the routine should allow page faults. [dan.carpenter@oracle.com: unmap the correct pointer] Link: http://lkml.kernel.org/r/20170113082608.GA3548@mwanda [akpm@linux-foundation.org: kunmap() takes a page*, per Hugh] Link: http://lkml.kernel.org/r/20161216144821.5183-20-aarcange@redhat.com Signed-off-by: Mike Kravetz Signed-off-by: Andrea Arcangeli Signed-off-by: Dan Carpenter Cc: "Dr. David Alan Gilbert" Cc: Hillf Danton Cc: Michael Rapoport Cc: Mike Rapoport Cc: Pavel Emelyanov Cc: Hugh Dickins Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index 4ade940d105c..d7676a68c80a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4155,7 +4155,8 @@ void copy_user_huge_page(struct page *dst, struct page *src, long copy_huge_page_from_user(struct page *dst_page, const void __user *usr_src, - unsigned int pages_per_huge_page) + unsigned int pages_per_huge_page, + bool allow_pagefault) { void *src = (void *)usr_src; void *page_kaddr; @@ -4163,11 +4164,17 @@ long copy_huge_page_from_user(struct page *dst_page, unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; for (i = 0; i < pages_per_huge_page; i++) { - page_kaddr = kmap_atomic(dst_page + i); + if (allow_pagefault) + page_kaddr = kmap(dst_page + i); + else + page_kaddr = kmap_atomic(dst_page + i); rc = copy_from_user(page_kaddr, (const void __user *)(src + i * PAGE_SIZE), PAGE_SIZE); - kunmap_atomic(page_kaddr); + if (allow_pagefault) + kunmap(dst_page + i); + else + kunmap_atomic(page_kaddr); ret_val -= (PAGE_SIZE - rc); if (rc) -- cgit v1.2.3-55-g7522