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authorBrian Geffon <bgeffon@google.com>2021-04-30 08:57:52 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-30 21:20:39 +0300
commit8593100444e93861fb5c867bf8cc104543259714 (patch)
tree3664b86272b51923d9746444123f5ff1cd252332 /tools/testing
parent14d071134c740cfe61c09fc506fd3ab052beea10 (diff)
downloadlinux-8593100444e93861fb5c867bf8cc104543259714.tar.xz
selftests: add a MREMAP_DONTUNMAP selftest for shmem
This test extends the current mremap tests to validate that the MREMAP_DONTUNMAP operation can be performed on shmem mappings. Link: https://lkml.kernel.org/r/20210323182520.2712101-3-bgeffon@google.com Signed-off-by: Brian Geffon <bgeffon@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Lokesh Gidra <lokeshgidra@google.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Peter Xu <peterx@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: "Michael S . Tsirkin" <mst@redhat.com> Cc: Brian Geffon <bgeffon@google.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Dmitry Safonov <dima@arista.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Alejandro Colomar <alx.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools/testing')
-rw-r--r--tools/testing/selftests/vm/mremap_dontunmap.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/tools/testing/selftests/vm/mremap_dontunmap.c b/tools/testing/selftests/vm/mremap_dontunmap.c
index 3a7b5ef0b0c6..f01dc4a85b0b 100644
--- a/tools/testing/selftests/vm/mremap_dontunmap.c
+++ b/tools/testing/selftests/vm/mremap_dontunmap.c
@@ -127,6 +127,57 @@ static void mremap_dontunmap_simple()
"unable to unmap source mapping");
}
+// This test validates that MREMAP_DONTUNMAP on a shared mapping works as expected.
+static void mremap_dontunmap_simple_shmem()
+{
+ unsigned long num_pages = 5;
+
+ int mem_fd = memfd_create("memfd", MFD_CLOEXEC);
+ BUG_ON(mem_fd < 0, "memfd_create");
+
+ BUG_ON(ftruncate(mem_fd, num_pages * page_size) < 0,
+ "ftruncate");
+
+ void *source_mapping =
+ mmap(NULL, num_pages * page_size, PROT_READ | PROT_WRITE,
+ MAP_FILE | MAP_SHARED, mem_fd, 0);
+ BUG_ON(source_mapping == MAP_FAILED, "mmap");
+
+ BUG_ON(close(mem_fd) < 0, "close");
+
+ memset(source_mapping, 'a', num_pages * page_size);
+
+ // Try to just move the whole mapping anywhere (not fixed).
+ void *dest_mapping =
+ mremap(source_mapping, num_pages * page_size, num_pages * page_size,
+ MREMAP_DONTUNMAP | MREMAP_MAYMOVE, NULL);
+ if (dest_mapping == MAP_FAILED && errno == EINVAL) {
+ // Old kernel which doesn't support MREMAP_DONTUNMAP on shmem.
+ BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+ "unable to unmap source mapping");
+ return;
+ }
+
+ BUG_ON(dest_mapping == MAP_FAILED, "mremap");
+
+ // Validate that the pages have been moved, we know they were moved if
+ // the dest_mapping contains a's.
+ BUG_ON(check_region_contains_byte
+ (dest_mapping, num_pages * page_size, 'a') != 0,
+ "pages did not migrate");
+
+ // Because the region is backed by shmem, we will actually see the same
+ // memory at the source location still.
+ BUG_ON(check_region_contains_byte
+ (source_mapping, num_pages * page_size, 'a') != 0,
+ "source should have no ptes");
+
+ BUG_ON(munmap(dest_mapping, num_pages * page_size) == -1,
+ "unable to unmap destination mapping");
+ BUG_ON(munmap(source_mapping, num_pages * page_size) == -1,
+ "unable to unmap source mapping");
+}
+
// This test validates MREMAP_DONTUNMAP will move page tables to a specific
// destination using MREMAP_FIXED, also while validating that the source
// remains intact.
@@ -300,6 +351,7 @@ int main(void)
BUG_ON(page_buffer == MAP_FAILED, "unable to mmap a page.");
mremap_dontunmap_simple();
+ mremap_dontunmap_simple_shmem();
mremap_dontunmap_simple_fixed();
mremap_dontunmap_partial_mapping();
mremap_dontunmap_partial_mapping_overwrite();