On 2026-05-01 11:25, Mike Rapoport wrote:
On Thu, Apr 30, 2026 at 02:31:48PM -0400, Luiz Capitulino wrote:
On 2026-04-28 16:42, Mike Rapoport wrote:
From: "Mike Rapoport (Microsoft)" <[email protected]>
A lot of tests require free HugeTLB pages. Some need just a few default
huge pages, some need a certain amount of memory available as HugeTLB, and
some just skip lots of tests if huge pages of all supported sizes are not
available.
This all resulted in a huge mess in run_vmtests.sh that sets up some huge
pages, adjusts them later and restores some of the settings if the stars
align.
Add APIs that allow saving the state of HugeTLB and setting up the desired
amount of HugeTLB pages.
Saving the state also registers atexit() callback and signal handler that
will ensure restoration of HugeTLB state.
Since many tests use both HugeTLB and THP, the atexit() callbacks and
signal handler are restoring both.
For kselftest_harness tests that run fixture setups and test in child
processes add a constructor that will save and restore settings in the main
process.
Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
---
.../testing/selftests/mm/hugepage_settings.c | 178 +++++++++++++++---
.../testing/selftests/mm/hugepage_settings.h | 30 ++-
2 files changed, 183 insertions(+), 25 deletions(-)
diff --git a/tools/testing/selftests/mm/hugepage_settings.c
b/tools/testing/selftests/mm/hugepage_settings.c
index 4ae7332b5e1b..9d31b53dbc67 100644
--- a/tools/testing/selftests/mm/hugepage_settings.c
+++ b/tools/testing/selftests/mm/hugepage_settings.c
@@ -306,31 +306,12 @@ void thp_restore_settings(void)
thp_write_settings(&saved_settings);
}
-static void thp_restore_settings_atexit(void)
+static void __thp_save_settings(void)
{
- thp_restore_settings();
-}
-
-static void thp_restore_settings_sighandler(int sig)
-{
- /* exit() will invoke the thp_restore_settings_atexit handler. */
- exit(KSFT_FAIL);
-}
+ if (!thp_available())
+ return;
-void thp_save_settings(void)
-{
thp_read_settings(&saved_settings);
-
- /*
- * setup exit hooks to make sure THP settings are restored on graceful
- * and error exits and signals
- */
- atexit(thp_restore_settings_atexit);
- signal(SIGTERM, thp_restore_settings_sighandler);
- signal(SIGINT, thp_restore_settings_sighandler);
- signal(SIGHUP, thp_restore_settings_sighandler);
- signal(SIGQUIT, thp_restore_settings_sighandler);
-
thp_settings_saved = true;
}
@@ -399,11 +380,31 @@ bool thp_is_enabled(void)
return mode == 1 || mode == 3;
}
+#define HUGETLB_MAX_NR_PAGESIZES 10
+struct hugetlb_settings {
+ unsigned long free_hugepages[HUGETLB_MAX_NR_PAGESIZES];
It looks like we don't actually use this in the API or maybe I'm missing
something?
Yes, it's used only in later patches.
I don't see it, the patch below builds fine (again, sorry in advance if
I'm missing something obvious):
diff --git a/tools/testing/selftests/mm/hugepage_settings.c
b/tools/testing/selftests/mm/hugepage_settings.c
index 097ba085f423..a023cfeb69c5 100644
--- a/tools/testing/selftests/mm/hugepage_settings.c
+++ b/tools/testing/selftests/mm/hugepage_settings.c
@@ -341,7 +341,6 @@ bool thp_is_enabled(void)
#define HUGETLB_MAX_NR_PAGESIZES 10
struct hugetlb_settings {
- unsigned long free_hugepages[HUGETLB_MAX_NR_PAGESIZES];
unsigned long nr_hugepages[HUGETLB_MAX_NR_PAGESIZES];
unsigned long sizes[HUGETLB_MAX_NR_PAGESIZES];
unsigned long default_size;
@@ -509,7 +508,6 @@ static void __hugetlb_save_settings(void)
if (!sz)
continue;
- settings->free_hugepages[i] = hugetlb_free_pages(sz);
settings->nr_hugepages[i] = hugetlb_nr_pages(sz);
}
I felt it would be too churny to add users in this patch.
Otherwise, the API looks great to me. But if you allow me to bikeshed :)
I think I'd do:
struct hugetlb_state {
unsigned long nr_hugepages;
unsigned long size;
};
struct hugetlb_settings {
struct hugetlb_state hstate[HUGETLB_MAX_PAGESIZES];
unsigned long default_size;
int nr_sizes;
};
It might be slightly nicer abstraction but ...
+static void __hugetlb_save_settings(void)
+{
+ struct hugetlb_settings *settings = &hugetlb_saved_settings;
+ int nr_sizes;
+
+ settings->default_size = default_huge_page_size();
+ if (!settings->default_size)
+ return;
+
+ nr_sizes = detect_hugetlb_page_sizes(settings->sizes,
+ HUGETLB_MAX_NR_PAGESIZES);
... this immediately becomes more complex.
+ if (!nr_sizes) {
+ settings->default_size = 0;
+ return;
+ }
+
+ for (int i = 0; i < nr_sizes; i++) {
+ unsigned long sz = settings->sizes[i];
+
+ if (!sz)
+ continue;
+
+ settings->free_hugepages[i] = hugetlb_free_pages(sz);
+ settings->nr_hugepages[i] = hugetlb_nr_pages(sz);
And this as well.
We'd need a little more code to handle those cases, may or may not be
worth it. But enough bikesheding from my side :) the series is great as
is.
