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Commit 230ca982 authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
Browse files

userfaultfd: non-cooperative: add madvise() event for MADV_FREE request 

MADV_FREE is identical to MADV_DONTNEED from the point of view of uffd
monitor.  The monitor has to stop handling #PF events in the range being
freed.  We are reusing userfaultfd_remove callback along with the logic
required to re-get and re-validate the VMA which may change or disappear
because userfaultfd_remove releases mmap_sem.

Link: http://lkml.kernel.org/r/1497876311-18615-1-git-send-email-rppt@linux.vnet.ibm.com


Signed-off-by: default avatarMike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 76b6f9b7

mm/madvise.c

+22 −20
Original line number Diff line number Diff line
@@ -451,9 +451,6 @@ static int madvise_free_single_vma(struct vm_area_struct *vma, 
	struct mm_struct *mm = vma->vm_mm;

	struct mmu_gather tlb;



	if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))

		return -EINVAL;



	/* MADV_FREE works for only anon vma at the moment */

	if (!vma_is_anonymous(vma))

		return -EINVAL;
@@ -477,14 +474,6 @@ static int madvise_free_single_vma(struct vm_area_struct *vma, 
	return 0;

}



static long madvise_free(struct vm_area_struct *vma,

			     struct vm_area_struct **prev,

			     unsigned long start, unsigned long end)

{

	*prev = vma;

	return madvise_free_single_vma(vma, start, end);

}



/*

 * Application no longer needs these pages.  If the pages are dirty,

 * it's OK to just throw them away.  The app will be more careful about
@@ -504,9 +493,17 @@ static long madvise_free(struct vm_area_struct *vma, 
 * An interface that causes the system to free clean pages and flush

 * dirty pages is already available as msync(MS_INVALIDATE).

 */

static long madvise_dontneed(struct vm_area_struct *vma,

			     struct vm_area_struct **prev,

static long madvise_dontneed_single_vma(struct vm_area_struct *vma,

					unsigned long start, unsigned long end)

{

	zap_page_range(vma, start, end - start);

	return 0;

}



static long madvise_dontneed_free(struct vm_area_struct *vma,

				  struct vm_area_struct **prev,

				  unsigned long start, unsigned long end,

				  int behavior)

{

	*prev = vma;

	if (!can_madv_dontneed_vma(vma))
@@ -526,7 +523,8 @@ static long madvise_dontneed(struct vm_area_struct *vma, 
			 * is also < vma->vm_end. If start <

			 * vma->vm_start it means an hole materialized

			 * in the user address space within the

			 * virtual range passed to MADV_DONTNEED.

			 * virtual range passed to MADV_DONTNEED

			 * or MADV_FREE.

			 */

			return -ENOMEM;

		}
@@ -537,7 +535,7 @@ static long madvise_dontneed(struct vm_area_struct *vma, 
			 * Don't fail if end > vma->vm_end. If the old

			 * vma was splitted while the mmap_sem was

			 * released the effect of the concurrent

			 * operation may not cause MADV_DONTNEED to

			 * operation may not cause madvise() to

			 * have an undefined result. There may be an

			 * adjacent next vma that we'll walk

			 * next. userfaultfd_remove() will generate an
@@ -549,8 +547,13 @@ static long madvise_dontneed(struct vm_area_struct *vma, 
		}

		VM_WARN_ON(start >= end);

	}

	zap_page_range(vma, start, end - start);

	return 0;



	if (behavior == MADV_DONTNEED)

		return madvise_dontneed_single_vma(vma, start, end);

	else if (behavior == MADV_FREE)

		return madvise_free_single_vma(vma, start, end);

	else

		return -EINVAL;

}



/*
@@ -656,9 +659,8 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, 
	case MADV_WILLNEED:

		return madvise_willneed(vma, prev, start, end);

	case MADV_FREE:

		return madvise_free(vma, prev, start, end);

	case MADV_DONTNEED:

		return madvise_dontneed(vma, prev, start, end);

		return madvise_dontneed_free(vma, prev, start, end, behavior);

	default:

		return madvise_behavior(vma, prev, start, end, behavior);

	}