The patch titled
Subject: userfaultfd: hugetlbfs: add userfaultfd hugetlb hook
has been added to the -mm tree. Its filename is
userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Subject: userfaultfd: hugetlbfs: add userfaultfd hugetlb hook
When processing a hugetlb fault for no page present, check the vma to
determine if faults are to be handled via userfaultfd. If so, drop the
hugetlb_fault_mutex and call handle_userfault().
Link: http://lkml.kernel.org/r/20161216144821.5183-21-aarcange@xxxxxxxxxx
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff -puN mm/hugetlb.c~userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook mm/hugetlb.c
--- a/mm/hugetlb.c~userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook
+++ a/mm/hugetlb.c
@@ -32,6 +32,7 @@
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
#include <linux/node.h>
+#include <linux/userfaultfd_k.h>
#include "internal.h"
int hugepages_treat_as_movable;
@@ -3661,6 +3662,38 @@ retry:
size = i_size_read(mapping->host) >> huge_page_shift(h);
if (idx >= size)
goto out;
+
+ /*
+ * Check for page in userfault range
+ */
+ if (userfaultfd_missing(vma)) {
+ u32 hash;
+ struct vm_fault vmf = {
+ .vma = vma,
+ .address = address,
+ .flags = flags,
+ /*
+ * Hard to debug if it ends up being
+ * used by a callee that assumes
+ * something about the other
+ * uninitialized fields... same as in
+ * memory.c
+ */
+ };
+
+ /*
+ * hugetlb_fault_mutex must be dropped before
+ * handling userfault. Reacquire after handling
+ * fault to make calling code simpler.
+ */
+ hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping,
+ idx, address);
+ mutex_unlock(&hugetlb_fault_mutex_table[hash]);
+ ret = handle_userfault(&vmf, VM_UFFD_MISSING);
+ mutex_lock(&hugetlb_fault_mutex_table[hash]);
+ goto out;
+ }
+
page = alloc_huge_page(vma, address, 0);
if (IS_ERR(page)) {
ret = PTR_ERR(page);
_
Patches currently in -mm which might be from mike.kravetz@xxxxxxxxxx are
userfaultfd-hugetlbfs-add-copy_huge_page_from_user-for-hugetlb-userfaultfd-support.patch
userfaultfd-hugetlbfs-add-hugetlb_mcopy_atomic_pte-for-userfaultfd-support.patch
userfaultfd-hugetlbfs-add-__mcopy_atomic_hugetlb-for-huge-page-uffdio_copy.patch
userfaultfd-hugetlbfs-fix-__mcopy_atomic_hugetlb-retry-error-processing.patch
userfaultfd-hugetlbfs-add-userfaultfd-hugetlb-hook.patch
userfaultfd-hugetlbfs-allow-registration-of-ranges-containing-huge-pages.patch
userfaultfd-hugetlbfs-add-userfaultfd_hugetlb-test.patch
userfaultfd-hugetlbfs-userfaultfd_huge_must_wait-for-hugepmd-ranges.patch
userfaultfd-hugetlbfs-reserve-count-on-error-in-__mcopy_atomic_hugetlb.patch
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