On 03.08.23 21:05, Peter Xu wrote:
On Thu, Aug 03, 2023 at 04:32:07PM +0200, David Hildenbrand wrote:
Let's extend mmap_and_merge_range() to test if anything in the current
process was merged. range_maps_duplicates() is too unreliable for that
use case, so instead look at KSM stats.
Trigger a complete unmerge first, to cleanup the stable tree and
stabilize accounting of merged pages.
Note that we're using /proc/self/ksm_merging_pages instead of
/proc/self/ksm_stat, because that one is available in more existing
kernels.
If /proc/self/ksm_merging_pages can't be opened, we can't perform any
checks and simply skip them.
We have to special-case the shared zeropage for now. But the only user
-- test_unmerge_zero_pages() -- performs its own merge checks.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Hi Peter,
thanks for the review!
Acked-by: Peter Xu <peterx@xxxxxxxxxx>
One nitpick:
---
.../selftests/mm/ksm_functional_tests.c | 47 +++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c
index 0de9d33cd565..cb63b600cb4f 100644
--- a/tools/testing/selftests/mm/ksm_functional_tests.c
+++ b/tools/testing/selftests/mm/ksm_functional_tests.c
@@ -30,6 +30,7 @@
static int ksm_fd;
static int ksm_full_scans_fd;
static int proc_self_ksm_stat_fd;
+static int proc_self_ksm_merging_pages_fd;
static int ksm_use_zero_pages_fd;
static int pagemap_fd;
static size_t pagesize;
@@ -88,6 +89,22 @@ static long get_my_ksm_zero_pages(void)
return my_ksm_zero_pages;
}
+static long get_my_merging_pages(void)
+{
+ char buf[10];
+ ssize_t ret;
+
+ if (proc_self_ksm_merging_pages_fd < 0)
+ return proc_self_ksm_merging_pages_fd;
Better do the fds check all in main(), e.g. not all callers below considers
negative values, so -1 can pass "if (get_my_merging_pages())" etc.
The two existing callers should be handling it correctly:
if (get_my_merging_pages() > 0)
-> fail
if (val && !get_my_merging_pages()
-> fail
Both will pass on negative values, unless I am missing something.
I tried to keep the test working also on older kernels where
ksm_merging_pages does not exist yet (it's ~1 year old).
Anyhow, if you think it's better to make the test fail on these setups,
I can change it.
--
Cheers,
David / dhildenb
