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/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 dec628b26f59..5d20af921a30 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3973,7 +3973,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, ret = copy_huge_page_from_user(page, (const void __user *) src_addr, - pages_per_huge_page(h)); + pages_per_huge_page(h), false); /* fallback to copy_from_user outside mmap_sem */ if (unlikely(ret)) { -- cgit