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From: Andrea Arcangeli <aarcange@redhat.com>
Subject: [PATCH 20/33] userfaultfd: introduce vma_can_userfault
Date: Wed,  2 Nov 2016 20:33:52 +0100
Message-Id: <1478115245-32090-21-git-send-email-aarcange@redhat.com>
In-Reply-To: <1478115245-32090-1-git-send-email-aarcange@redhat.com>
References: <1478115245-32090-1-git-send-email-aarcange@redhat.com>
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, Michael Rapoport <RAPOPORT@il.ibm.com>, "Dr. David Alan Gilbert"@v2.random, " <dgilbert@redhat.com>,  Mike Kravetz <mike.kravetz@oracle.com>,  Shaohua Li <shli@fb.com>,  Pavel Emelyanov <xemul@parallels.com>"@v2.random

From: Mike Rapoport <rppt@linux.vnet.ibm.com>

Check whether a VMA can be used with userfault in more compact way

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
 fs/userfaultfd.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 9552734..387fe77 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1060,6 +1060,11 @@ static __always_inline int validate_range(struct mm_struct *mm,
 	return 0;
 }
 
+static inline bool vma_can_userfault(struct vm_area_struct *vma)
+{
+	return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma);
+}
+
 static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 				unsigned long arg)
 {
@@ -1149,7 +1154,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 
 		/* check not compatible vmas */
 		ret = -EINVAL;
-		if (!vma_is_anonymous(cur) && !is_vm_hugetlb_page(cur))
+		if (!vma_can_userfault(cur))
 			goto out_unlock;
 		/*
 		 * If this vma contains ending address, and huge pages
@@ -1193,7 +1198,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 	do {
 		cond_resched();
 
-		BUG_ON(!vma_is_anonymous(vma) && !is_vm_hugetlb_page(vma));
+		BUG_ON(!vma_can_userfault(vma));
 		BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
 		       vma->vm_userfaultfd_ctx.ctx != ctx);
 
@@ -1331,7 +1336,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 		 * provides for more strict behavior to notice
 		 * unregistration errors.
 		 */
-		if (!vma_is_anonymous(cur) && !is_vm_hugetlb_page(cur))
+		if (!vma_can_userfault(cur))
 			goto out_unlock;
 
 		found = true;
@@ -1345,7 +1350,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	do {
 		cond_resched();
 
-		BUG_ON(!vma_is_anonymous(vma) && !is_vm_hugetlb_page(vma));
+		BUG_ON(!vma_can_userfault(vma));
 
 		/*
 		 * Nothing to do: this vma is already registered into this

--
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