From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f72.google.com (mail-it0-f72.google.com [209.85.214.72]) by kanga.kvack.org (Postfix) with ESMTP id B73A86B0271 for ; Fri, 16 Dec 2016 09:48:28 -0500 (EST) Received: by mail-it0-f72.google.com with SMTP id g187so21100989itc.2 for ; Fri, 16 Dec 2016 06:48:28 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id e205si6178890ioa.58.2016.12.16.06.48.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Dec 2016 06:48:28 -0800 (PST) From: Andrea Arcangeli Subject: [PATCH 19/42] userfaultfd: hugetlbfs: fix __mcopy_atomic_hugetlb retry/error processing Date: Fri, 16 Dec 2016 15:47:58 +0100 Message-Id: <20161216144821.5183-20-aarcange@redhat.com> In-Reply-To: <20161216144821.5183-1-aarcange@redhat.com> References: <20161216144821.5183-1-aarcange@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, Andrew Morton Cc: Michael Rapoport , "Dr. David Alan Gilbert" , Mike Kravetz , Pavel Emelyanov , Hillf Danton From: Mike Kravetz 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. Signed-off-by: Mike Kravetz Signed-off-by: Andrea Arcangeli --- include/linux/mm.h | 3 ++- mm/hugetlb.c | 2 +- mm/memory.c | 13 ++++++++++--- mm/userfaultfd.c | 2 +- 4 files changed, 14 insertions(+), 6 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 298b265..f9914ba 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2396,7 +2396,8 @@ extern void copy_user_huge_page(struct page *dst, struct page *src, unsigned int pages_per_huge_page); extern 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); #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ extern struct page_ext_operations debug_guardpage_ops; diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f815f56..9ea7588 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3954,7 +3954,7 @@ 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)) { diff --git a/mm/memory.c b/mm/memory.c index 9e4ecf1..5c9bfd2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4142,7 +4142,8 @@ 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; @@ -4150,11 +4151,17 @@ 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(page_kaddr); + else + kunmap_atomic(page_kaddr); ret_val -= (PAGE_SIZE - rc); if (rc) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index ef0495b..0997674 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -274,7 +274,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, err = copy_huge_page_from_user(page, (const void __user *)src_addr, - pages_per_huge_page(h)); + pages_per_huge_page(h), true); if (unlikely(err)) { err = -EFAULT; goto out; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org