From: Mike Kravetz <mike.kravetz@oracle.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>,
David Hildenbrand <david@redhat.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Mina Almasry <almasrymina@google.com>,
Michal Hocko <mhocko@suse.com>, Peter Xu <peterx@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Shuah Khan <shuah@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: [PATCH v2 1/3] mm: enable MADV_DONTNEED for hugetlb mappings
Date: Tue, 1 Feb 2022 17:40:32 -0800 [thread overview]
Message-ID: <20220202014034.182008-2-mike.kravetz@oracle.com> (raw)
In-Reply-To: <20220202014034.182008-1-mike.kravetz@oracle.com>
MADV_DONTNEED is currently disabled for hugetlb mappings. This
certainly makes sense in shared file mappings as the pagecache maintains
a reference to the page and it will never be freed. However, it could
be useful to unmap and free pages in private mappings.
The only thing preventing MADV_DONTNEED from working on hugetlb mappings
is a check in can_madv_lru_vma(). To allow support for hugetlb mappings
create and use a new routine madvise_dontneed_free_valid_vma() that will
allow hugetlb mappings. Also, before calling zap_page_range in the
DONTNEED case align start and size to huge page size for hugetlb vmas.
madvise only requires PAGE_SIZE alignment, but the hugetlb unmap routine
requires huge page size alignment.
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
mm/madvise.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c
index 5604064df464..7ae891e030a4 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -796,10 +796,30 @@ static int madvise_free_single_vma(struct vm_area_struct *vma,
static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
+ /*
+ * start and size (end - start) must be huge page size aligned
+ * for hugetlb vmas.
+ */
+ if (is_vm_hugetlb_page(vma)) {
+ struct hstate *h = hstate_vma(vma);
+
+ start = ALIGN_DOWN(start, huge_page_size(h));
+ end = ALIGN(end, huge_page_size(h));
+ }
+
zap_page_range(vma, start, end - start);
return 0;
}
+static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
+ int behavior)
+{
+ if (is_vm_hugetlb_page(vma))
+ return behavior == MADV_DONTNEED;
+ else
+ return can_madv_lru_vma(vma);
+}
+
static long madvise_dontneed_free(struct vm_area_struct *vma,
struct vm_area_struct **prev,
unsigned long start, unsigned long end,
@@ -808,7 +828,7 @@ static long madvise_dontneed_free(struct vm_area_struct *vma,
struct mm_struct *mm = vma->vm_mm;
*prev = vma;
- if (!can_madv_lru_vma(vma))
+ if (!madvise_dontneed_free_valid_vma(vma, behavior))
return -EINVAL;
if (!userfaultfd_remove(vma, start, end)) {
@@ -830,7 +850,7 @@ static long madvise_dontneed_free(struct vm_area_struct *vma,
*/
return -ENOMEM;
}
- if (!can_madv_lru_vma(vma))
+ if (!madvise_dontneed_free_valid_vma(vma, behavior))
return -EINVAL;
if (end > vma->vm_end) {
/*
--
2.34.1
next prev parent reply other threads:[~2022-02-02 1:41 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-02 1:40 [PATCH v2 0/3] Add hugetlb MADV_DONTNEED support Mike Kravetz
2022-02-02 1:40 ` Mike Kravetz [this message]
2022-02-02 8:14 ` [PATCH v2 1/3] mm: enable MADV_DONTNEED for hugetlb mappings David Hildenbrand
2022-02-02 19:32 ` Mike Kravetz
2022-02-04 8:35 ` David Hildenbrand
2022-02-07 23:47 ` Mike Kravetz
2022-02-10 13:09 ` David Hildenbrand
2022-02-10 22:11 ` Mike Kravetz
2022-02-11 8:43 ` David Hildenbrand
2022-02-10 3:21 ` Peter Xu
2022-02-10 21:36 ` Mike Kravetz
2022-02-11 2:28 ` Peter Xu
2022-02-11 19:08 ` Axel Rasmussen
2022-02-11 19:18 ` Mike Kravetz
2022-02-02 1:40 ` [PATCH v2 2/3] selftests/vm: add hugetlb madvise MADV_DONTNEED MADV_REMOVE test Mike Kravetz
2022-02-02 1:40 ` [PATCH v2 3/3] userfaultfd/selftests: enable huegtlb remap and remove event testing Mike Kravetz
2022-02-02 6:11 ` Mike Rapoport
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