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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@redhat.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2017-02-22 15:43:01 -08:00 committed by Linus Torvalds
parent 810a56b943
commit 1a1aad8a9b
1 changed files with 33 additions and 0 deletions
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33
mm/hugetlb.c
View File

@ -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;
@ -3680,6 +3681,38 @@ 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);