Subject: [PATCH] mm: do not call do_fault_around for non-linear fault
From: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
To: linux-mm@kvack.org, Hugh Dickins <hughd@google.com>,
        linux-kernel@vger.kernel.org, Sasha Levin <sasha.levin@oracle.com>
Cc: Ingo Korb <ingo.korb@tu-dortmund.de>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Dave Jones <davej@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>, Ning Qu <quning@google.com>,
        Konstantin Khlebnikov <koct9i@gmail.com>
Date: Tue, 15 Jul 2014 15:58:32 +0400
Message-id: <20140715115832.18997.90349.stgit@buzz>
In-reply-to: <CALYGNiM9Fu9-i7hXMQNTUP69RfydN+2NqO29wZYd+4Gn25GbCQ@mail.gmail.com>
References: <CALYGNiM9Fu9-i7hXMQNTUP69RfydN+2NqO29wZYd+4Gn25GbCQ@mail.gmail.com>
User-Agent: StGit/0.17.1-dirty
MIME-version: 1.0
Content-type: text/plain; charset=utf-8
Content-transfer-encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org

From: Konstantin Khlebnikov <koct9i@gmail.com>

Faulting around non-linear page-fault has no sense and
breaks logic in do_fault_around because pgoff is shifted.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-by: "Ingo Korb" <ingo.korb@tu-dortmund.de>
---
 mm/memory.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index d67fd9f..7e8d820 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2882,7 +2882,8 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * if page by the offset is not ready to be mapped (cold cache or
 	 * something).
 	 */
-	if (vma->vm_ops->map_pages && fault_around_pages() > 1) {
+	if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
+	    fault_around_pages() > 1) {
 		pte = pte_offset_map_lock(mm, pmd, address, &ptl);
 		do_fault_around(vma, address, pte, pgoff, flags);
 		if (!pte_same(*pte, orig_pte))

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/