linux-kernel - [PATCH v4 13/27] mm: introduce do_wp_page

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Date:   Fri, 26 Apr 2019 12:51:37 +0800
From:   Peter Xu <peterx@...hat.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Maya Gokhale <gokhale2@...l.gov>,
        Jerome Glisse <jglisse@...hat.com>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>, peterx@...hat.com,
        Martin Cracauer <cracauer@...s.org>, Shaohua Li <shli@...com>,
        Denis Plotnikov <dplotnikov@...tuozzo.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Marty McFadden <mcfadden8@...l.gov>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: [PATCH v4 13/27] mm: introduce do_wp_page_cont()

The userfaultfd handling in do_wp_page() is very special comparing to
the rest of the function because it only postpones the real handling
of the page fault to the userspace program.  Isolate the handling part
of do_wp_page() into a new function called do_wp_page_cont() so that
we can use it somewhere else when resolving the userfault page fault.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 include/linux/mm.h | 2 ++
 mm/memory.c        | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index a5ac81188523..a2911de04cdd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -445,6 +445,8 @@ struct vm_fault {
 					 */
 };
 
+vm_fault_t do_wp_page_cont(struct vm_fault *vmf);
+
 /* page entry size for vm->huge_fault() */
 enum page_entry_size {
 	PE_SIZE_PTE = 0,
diff --git a/mm/memory.c b/mm/memory.c
index 64bd8075f054..ab98a1eb4702 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2497,6 +2497,14 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf)
 		return handle_userfault(vmf, VM_UFFD_WP);
 	}
 
+	return do_wp_page_cont(vmf);
+}
+
+vm_fault_t do_wp_page_cont(struct vm_fault *vmf)
+	__releases(vmf->ptl)
+{
+	struct vm_area_struct *vma = vmf->vma;
+
 	vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
 	if (!vmf->page) {
 		/*
-- 
2.17.1