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Commit 1a1aad8a authored by Mike Kravetz's avatar Mike Kravetz Committed by Linus Torvalds
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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: default avatarMike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarHillf 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 810a56b9

mm/hugetlb.c

+33 −0
Original line number Diff line number Diff line
@@ -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 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 
		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);