github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-03 20:14:06 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

tools/testing/selftests: add VMA merge tests for KSM merge

Browse Source 
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>
This commit is contained in:
Lorenzo Stoakes 2025-05-29 18:15:48 +01:00 committed by Andrew Morton
parent cf7e7a3503
commit 4a1ff347e4
1 changed files with 78 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
tools/testing/selftests/mm/merge.c
View File

@ -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 @@ TEST_F(merge, handle_uprobe_upon_merged_vma)
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