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| author | Lorenzo Stoakes <lorenzo.stoakes@oracle.com> | 2025-05-29 18:15:48 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-07-09 22:41:54 -0700 |
| commit | 4a1ff347e44ce45e8a5c15f466574583b019e4f9 (patch) | |
| tree | f68ad4cc5eaa42aa1a8d3455586702c3ffcc7dc9 | |
| parent | cf7e7a3503df0b71afd68ee84e9a09d4514cc2dd (diff) | |
| download | tip-4a1ff347e44ce45e8a5c15f466574583b019e4f9.tar.gz | |
tools/testing/selftests: add VMA merge tests for KSM merge
Add test to assert that we have now allowed merging of VMAs when KSM
merging-by-default has been set by prctl(PR_SET_MEMORY_MERGE, ...).
We simply perform a trivial mapping of adjacent VMAs expecting a merge,
however prior to recent changes implementing this mode earlier than
before, these merges would not have succeeded.
Assert that we have fixed this!
Link: https://lkml.kernel.org/r/6dec7aabf062c6b121cfac992c9c716cefdda00c.1748537921.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Tested-by: Chengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Stefan Roesch <shr@devkernel.io>
Cc: Xu Xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | tools/testing/selftests/mm/merge.c | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c index cc26480098ae87..150dd5baed2b46 100644 --- a/tools/testing/selftests/mm/merge.c +++ b/tools/testing/selftests/mm/merge.c @@ -2,11 +2,13 @@ #define _GNU_SOURCE #include "../kselftest_harness.h" +#include <linux/prctl.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/mman.h> +#include <sys/prctl.h> #include <sys/syscall.h> #include <sys/wait.h> #include <linux/perf_event.h> @@ -34,6 +36,11 @@ FIXTURE_TEARDOWN(merge) { ASSERT_EQ(munmap(self->carveout, 12 * self->page_size), 0); ASSERT_EQ(close_procmap(&self->procmap), 0); + /* + * Clear unconditionally, as some tests set this. It is no issue if this + * fails (KSM may be disabled for instance). + */ + prctl(PR_SET_MEMORY_MERGE, 0, 0, 0, 0); } TEST_F(merge, mprotect_unfaulted_left) @@ -498,4 +505,75 @@ out: remove(probe_file); } +TEST_F(merge, ksm_merge) +{ + unsigned int page_size = self->page_size; + char *carveout = self->carveout; + struct procmap_fd *procmap = &self->procmap; + char *ptr, *ptr2; + int err; + + /* + * Map two R/W immediately adjacent to one another, they should + * trivially merge: + * + * |-----------|-----------| + * | R/W | R/W | + * |-----------|-----------| + * ptr ptr2 + */ + + ptr = mmap(&carveout[page_size], page_size, PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr, MAP_FAILED); + ptr2 = mmap(&carveout[2 * page_size], page_size, + PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr2, MAP_FAILED); + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 2 * page_size); + + /* Unmap the second half of this merged VMA. */ + ASSERT_EQ(munmap(ptr2, page_size), 0); + + /* OK, now enable global KSM merge. We clear this on test teardown. */ + err = prctl(PR_SET_MEMORY_MERGE, 1, 0, 0, 0); + if (err == -1) { + int errnum = errno; + + /* Only non-failure case... */ + ASSERT_EQ(errnum, EINVAL); + /* ...but indicates we should skip. */ + SKIP(return, "KSM memory merging not supported, skipping."); + } + + /* + * Now map a VMA adjacent to the existing that was just made + * VM_MERGEABLE, this should merge as well. + */ + ptr2 = mmap(&carveout[2 * page_size], page_size, + PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr2, MAP_FAILED); + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 2 * page_size); + + /* Now this VMA altogether. */ + ASSERT_EQ(munmap(ptr, 2 * page_size), 0); + + /* Try the same operation as before, asserting this also merges fine. */ + ptr = mmap(&carveout[page_size], page_size, PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr, MAP_FAILED); + ptr2 = mmap(&carveout[2 * page_size], page_size, + PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr2, MAP_FAILED); + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 2 * page_size); +} + TEST_HARNESS_MAIN |