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From: Axel Rasmussen <axelrasmussen@google.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	Jerome Glisse <jglisse@redhat.com>, Joe Perches <joe@perches.com>,
	Lokesh Gidra <lokeshgidra@google.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	Peter Xu <peterx@redhat.com>, Shaohua Li <shli@fb.com>,
	Shuah Khan <shuah@kernel.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Wang Qing <wangqing@vivo.com>
Cc: linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-mm@kvack.org, Axel Rasmussen <axelrasmussen@google.com>,
	Brian Geffon <bgeffon@google.com>,
	"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
	Mina Almasry <almasrymina@google.com>,
	Oliver Upton <oupton@google.com>
Subject: [PATCH v4 06/10] userfaultfd/selftests: create alias mappings in the shmem test
Date: Tue, 20 Apr 2021 15:08:00 -0700
Message-ID: <20210420220804.486803-7-axelrasmussen@google.com> (raw)
In-Reply-To: <20210420220804.486803-1-axelrasmussen@google.com>

Previously, we just allocated two shm areas: area_src and area_dst. With
this commit, change this so we also allocate area_src_alias, and
area_dst_alias.

area_*_alias and area_* (respectively) point to the same underlying
physical pages, but are different VMAs. In a future commit in this
series, we'll leverage this setup to exercise minor fault handling
support for shmem, just like we do in the hugetlb_shared test.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
---
 tools/testing/selftests/vm/userfaultfd.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
index fc40831f818f..1f65c4ab7994 100644
--- a/tools/testing/selftests/vm/userfaultfd.c
+++ b/tools/testing/selftests/vm/userfaultfd.c
@@ -278,13 +278,29 @@ static void shmem_release_pages(char *rel_area)
 
 static void shmem_allocate_area(void **alloc_area)
 {
-	unsigned long offset =
-		alloc_area == (void **)&area_src ? 0 : nr_pages * page_size;
+	void *area_alias = NULL;
+	bool is_src = alloc_area == (void **)&area_src;
+	unsigned long offset = is_src ? 0 : nr_pages * page_size;
 
 	*alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
 			   MAP_SHARED, shm_fd, offset);
 	if (*alloc_area == MAP_FAILED)
 		err("mmap of memfd failed");
+
+	area_alias = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
+			  MAP_SHARED, shm_fd, offset);
+	if (area_alias == MAP_FAILED)
+		err("mmap of memfd alias failed");
+
+	if (is_src)
+		area_src_alias = area_alias;
+	else
+		area_dst_alias = area_alias;
+}
+
+static void shmem_alias_mapping(__u64 *start, size_t len, unsigned long offset)
+{
+	*start = (unsigned long)area_dst_alias + offset;
 }
 
 struct uffd_test_ops {
@@ -314,7 +330,7 @@ static struct uffd_test_ops shmem_uffd_test_ops = {
 	.expected_ioctls = SHMEM_EXPECTED_IOCTLS,
 	.allocate_area	= shmem_allocate_area,
 	.release_pages	= shmem_release_pages,
-	.alias_mapping = noop_alias_mapping,
+	.alias_mapping = shmem_alias_mapping,
 };
 
 static struct uffd_test_ops hugetlb_uffd_test_ops = {
-- 
2.31.1.368.gbe11c130af-goog


  parent reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-20 22:07 [PATCH v4 00/10] userfaultfd: add minor fault handling for shmem Axel Rasmussen
2021-04-20 22:07 ` [PATCH v4 01/10] userfaultfd/hugetlbfs: avoid including userfaultfd_k.h in hugetlb.h Axel Rasmussen
2021-04-27  2:05   ` Hugh Dickins
2021-04-20 22:07 ` [PATCH v4 02/10] userfaultfd/shmem: combine shmem_{mcopy_atomic,mfill_zeropage}_pte Axel Rasmussen
2021-04-20 22:07 ` [PATCH v4 03/10] userfaultfd/shmem: support UFFDIO_CONTINUE for shmem Axel Rasmussen
2021-04-22 20:22   ` Axel Rasmussen
2021-04-22 21:18     ` Peter Xu
2021-04-22 22:05       ` Axel Rasmussen
2021-04-27  2:19   ` Hugh Dickins
2021-04-27 15:54     ` Peter Xu
2021-04-27 16:57       ` Axel Rasmussen
2021-04-27 18:03         ` Peter Xu
2021-04-27 20:29           ` Axel Rasmussen
2021-04-27 20:42             ` Peter Xu
2021-04-27 20:59               ` Hugh Dickins
2021-04-20 22:07 ` [PATCH v4 04/10] userfaultfd/shmem: support minor fault registration " Axel Rasmussen
2021-04-27  2:23   ` Hugh Dickins
2021-04-27 15:57     ` Peter Xu
2021-04-27 17:03       ` Axel Rasmussen
2021-04-20 22:07 ` [PATCH v4 05/10] userfaultfd/selftests: use memfd_create for shmem test type Axel Rasmussen
2021-04-20 22:08 ` Axel Rasmussen [this message]
2021-04-20 22:08 ` [PATCH v4 07/10] userfaultfd/selftests: reinitialize test context in each test Axel Rasmussen
2021-04-20 22:08 ` [PATCH v4 08/10] userfaultfd/selftests: exercise minor fault handling shmem support Axel Rasmussen
2021-04-20 22:08 ` [PATCH v4 09/10] userfaultfd/shmem: modify shmem_mcopy_atomic_pte to use install_pte() Axel Rasmussen
2021-04-21  1:02   ` Peter Xu
2021-04-27  2:59     ` Hugh Dickins
2021-04-20 22:08 ` [PATCH v4 10/10] userfaultfd: update documentation to mention shmem minor faults Axel Rasmussen
2021-04-27  2:27   ` Hugh Dickins

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