The test will set the global system THP setting to never, madvise
or always depending on the fixture variant and the 2M setting to
inherit before it starts (and reset to original at teardown).
This tests if the process can:
- successfully set and get the policy to disable THPs completely.
- never get a hugepage when the THPs are completely disabled
with the prctl, including with MADV_HUGE and MADV_COLLAPSE.
- successfully reset the policy of the process.
- after reset, only get hugepages with:
- MADV_COLLAPSE when policy is set to never.
- MADV_HUGE and MADV_COLLAPSE when policy is set to madvise.
- always when policy is set to "always".
- repeat the above tests in a forked process to make sure
the policy is carried across forks.
Signed-off-by: Usama Arif <usamaarif642@gmail.com>
---
tools/testing/selftests/mm/.gitignore | 1 +
tools/testing/selftests/mm/Makefile | 1 +
.../testing/selftests/mm/prctl_thp_disable.c | 173 ++++++++++++++++++
tools/testing/selftests/mm/thp_settings.c | 9 +-
tools/testing/selftests/mm/thp_settings.h | 1 +
5 files changed, 184 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/mm/prctl_thp_disable.c
diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selftests/mm/.gitignore
index e7b23a8a05fe..eb023ea857b3 100644
--- a/tools/testing/selftests/mm/.gitignore
+++ b/tools/testing/selftests/mm/.gitignore
@@ -58,3 +58,4 @@ pkey_sighandler_tests_32
pkey_sighandler_tests_64
guard-regions
merge
+prctl_thp_disable
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index d13b3cef2a2b..2bb8d3ebc17c 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -86,6 +86,7 @@ TEST_GEN_FILES += on-fault-limit
TEST_GEN_FILES += pagemap_ioctl
TEST_GEN_FILES += pfnmap
TEST_GEN_FILES += process_madv
+TEST_GEN_FILES += prctl_thp_disable
TEST_GEN_FILES += thuge-gen
TEST_GEN_FILES += transhuge-stress
TEST_GEN_FILES += uffd-stress
diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c
new file mode 100644
index 000000000000..ef150180daf4
--- /dev/null
+++ b/tools/testing/selftests/mm/prctl_thp_disable.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Basic tests for PR_GET/SET_THP_DISABLE prctl calls
+ *
+ * Author(s): Usama Arif <usamaarif642@gmail.com>
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+
+#include "../kselftest_harness.h"
+#include "thp_settings.h"
+#include "vm_util.h"
+
+static int sz2ord(size_t size, size_t pagesize)
+{
+ return __builtin_ctzll(size / pagesize);
+}
+
+enum thp_collapse_type {
+ THP_COLLAPSE_NONE,
+ THP_COLLAPSE_MADV_HUGEPAGE, /* MADV_HUGEPAGE before access */
+ THP_COLLAPSE_MADV_COLLAPSE, /* MADV_COLLAPSE after access */
+};
+
+/*
+ * Function to mmap a buffer, fault it in, madvise it appropriately (before
+ * page fault for MADV_HUGE, and after for MADV_COLLAPSE), and check if the
+ * mmap region is huge.
+ * Returns:
+ * 0 if test doesn't give hugepage
+ * 1 if test gives a hugepage
+ * -errno if mmap fails
+ */
+static int test_mmap_thp(enum thp_collapse_type madvise_buf, size_t pmdsize)
+{
+ char *mem, *mmap_mem;
+ size_t mmap_size;
+ int ret;
+
+ /* For alignment purposes, we need twice the THP size. */
+ mmap_size = 2 * pmdsize;
+ mmap_mem = (char *)mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ if (mmap_mem == MAP_FAILED)
+ return -errno;
+
+ /* We need a THP-aligned memory area. */
+ mem = (char *)(((uintptr_t)mmap_mem + pmdsize) & ~(pmdsize - 1));
+
+ if (madvise_buf == THP_COLLAPSE_MADV_HUGEPAGE)
+ madvise(mem, pmdsize, MADV_HUGEPAGE);
+
+ /* Ensure memory is allocated */
+ memset(mem, 1, pmdsize);
+
+ if (madvise_buf == THP_COLLAPSE_MADV_COLLAPSE)
+ madvise(mem, pmdsize, MADV_COLLAPSE);
+
+ /* HACK: make sure we have a separate VMA that we can check reliably. */
+ mprotect(mem, pmdsize, PROT_READ);
+
+ ret = check_huge_anon(mem, 1, pmdsize);
+ munmap(mmap_mem, mmap_size);
+ return ret;
+}
+
+static void prctl_thp_disable_completely_test(struct __test_metadata *const _metadata,
+ size_t pmdsize,
+ enum thp_enabled thp_policy)
+{
+ ASSERT_EQ(prctl(PR_GET_THP_DISABLE, NULL, NULL, NULL, NULL), 1);
+
+ /* tests after prctl overrides global policy */
+ ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize), 0);
+
+ ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize), 0);
+
+ ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 0);
+
+ /* Reset to global policy */
+ ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 0, NULL, NULL, NULL), 0);
+
+ /* tests after prctl is cleared, and only global policy is effective */
+ ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_NONE, pmdsize),
+ thp_policy == THP_ALWAYS ? 1 : 0);
+
+ ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_HUGEPAGE, pmdsize),
+ thp_policy == THP_NEVER ? 0 : 1);
+
+ ASSERT_EQ(test_mmap_thp(THP_COLLAPSE_MADV_COLLAPSE, pmdsize), 1);
+}
+
+FIXTURE(prctl_thp_disable_completely)
+{
+ struct thp_settings settings;
+ size_t pmdsize;
+};
+
+FIXTURE_VARIANT(prctl_thp_disable_completely)
+{
+ enum thp_enabled thp_policy;
+};
+
+FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, never)
+{
+ .thp_policy = THP_NEVER,
+};
+
+FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, madvise)
+{
+ .thp_policy = THP_MADVISE,
+};
+
+FIXTURE_VARIANT_ADD(prctl_thp_disable_completely, always)
+{
+ .thp_policy = THP_ALWAYS,
+};
+
+FIXTURE_SETUP(prctl_thp_disable_completely)
+{
+ if (!thp_available())
+ SKIP(return, "Transparent Hugepages not available\n");
+
+ self->pmdsize = read_pmd_pagesize();
+ if (!self->pmdsize)
+ SKIP(return, "Unable to read PMD size\n");
+
+ thp_save_settings();
+ thp_read_settings(&self->settings);
+ self->settings.thp_enabled = variant->thp_policy;
+ self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
+ thp_write_settings(&self->settings);
+}
+
+FIXTURE_TEARDOWN(prctl_thp_disable_completely)
+{
+ thp_restore_settings();
+}
+
+TEST_F(prctl_thp_disable_completely, nofork)
+{
+ ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 1, NULL, NULL, NULL), 0);
+ prctl_thp_disable_completely_test(_metadata, self->pmdsize, variant->thp_policy);
+}
+
+TEST_F(prctl_thp_disable_completely, fork)
+{
+ int ret = 0;
+ pid_t pid;
+
+ ASSERT_EQ(prctl(PR_SET_THP_DISABLE, 1, NULL, NULL, NULL), 0);
+
+ /* Make sure prctl changes are carried across fork */
+ pid = fork();
+ ASSERT_GE(pid, 0);
+
+ if (!pid)
+ prctl_thp_disable_completely_test(_metadata, self->pmdsize, variant->thp_policy);
+
+ wait(&ret);
+ if (WIFEXITED(ret))
+ ret = WEXITSTATUS(ret);
+ else
+ ret = -EINVAL;
+ ASSERT_EQ(ret, 0);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
index bad60ac52874..574bd0f8ae48 100644
--- a/tools/testing/selftests/mm/thp_settings.c
+++ b/tools/testing/selftests/mm/thp_settings.c
@@ -382,10 +382,17 @@ unsigned long thp_shmem_supported_orders(void)
return __thp_supported_orders(true);
}
-bool thp_is_enabled(void)
+bool thp_available(void)
{
if (access(THP_SYSFS, F_OK) != 0)
return false;
+ return true;
+}
+
+bool thp_is_enabled(void)
+{
+ if (!thp_available())
+ return false;
int mode = thp_read_string("enabled", thp_enabled_strings);
diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/selftests/mm/thp_settings.h
index 6c07f70beee9..76eeb712e5f1 100644
--- a/tools/testing/selftests/mm/thp_settings.h
+++ b/tools/testing/selftests/mm/thp_settings.h
@@ -84,6 +84,7 @@ void thp_set_read_ahead_path(char *path);
unsigned long thp_supported_orders(void);
unsigned long thp_shmem_supported_orders(void);
+bool thp_available(void);
bool thp_is_enabled(void);
#endif /* __THP_SETTINGS_H__ */
--
2.47.3On 04.08.25 17:40, Usama Arif wrote:
> The test will set the global system THP setting to never, madvise
> or always depending on the fixture variant and the 2M setting to
> inherit before it starts (and reset to original at teardown).
>
> This tests if the process can:
> - successfully set and get the policy to disable THPs completely.
> - never get a hugepage when the THPs are completely disabled
> with the prctl, including with MADV_HUGE and MADV_COLLAPSE.
> - successfully reset the policy of the process.
> - after reset, only get hugepages with:
> - MADV_COLLAPSE when policy is set to never.
> - MADV_HUGE and MADV_COLLAPSE when policy is set to madvise.
> - always when policy is set to "always".
> - repeat the above tests in a forked process to make sure
> the policy is carried across forks.
>
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> ---
> tools/testing/selftests/mm/.gitignore | 1 +
> tools/testing/selftests/mm/Makefile | 1 +
> .../testing/selftests/mm/prctl_thp_disable.c | 173 ++++++++++++++++++
> tools/testing/selftests/mm/thp_settings.c | 9 +-
> tools/testing/selftests/mm/thp_settings.h | 1 +
> 5 files changed, 184 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/mm/prctl_thp_disable.c
>
> diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selftests/mm/.gitignore
> index e7b23a8a05fe..eb023ea857b3 100644
> --- a/tools/testing/selftests/mm/.gitignore
> +++ b/tools/testing/selftests/mm/.gitignore
> @@ -58,3 +58,4 @@ pkey_sighandler_tests_32
> pkey_sighandler_tests_64
> guard-regions
> merge
> +prctl_thp_disable
> diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
> index d13b3cef2a2b..2bb8d3ebc17c 100644
> --- a/tools/testing/selftests/mm/Makefile
> +++ b/tools/testing/selftests/mm/Makefile
> @@ -86,6 +86,7 @@ TEST_GEN_FILES += on-fault-limit
> TEST_GEN_FILES += pagemap_ioctl
> TEST_GEN_FILES += pfnmap
> TEST_GEN_FILES += process_madv
> +TEST_GEN_FILES += prctl_thp_disable
> TEST_GEN_FILES += thuge-gen
> TEST_GEN_FILES += transhuge-stress
> TEST_GEN_FILES += uffd-stress
> diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c
> new file mode 100644
> index 000000000000..ef150180daf4
> --- /dev/null
> +++ b/tools/testing/selftests/mm/prctl_thp_disable.c
> @@ -0,0 +1,173 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Basic tests for PR_GET/SET_THP_DISABLE prctl calls
> + *
> + * Author(s): Usama Arif <usamaarif642@gmail.com>
> + */
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +#include <sys/prctl.h>
> +#include <sys/wait.h>
> +
> +#include "../kselftest_harness.h"
> +#include "thp_settings.h"
> +#include "vm_util.h"
> +
> +static int sz2ord(size_t size, size_t pagesize)
> +{
> + return __builtin_ctzll(size / pagesize);
> +}
Note: We have this helper duplicated elsewhere (e.g., cow.c).
See [1] how we're going to clean it up.
Not sure how to resolve this. Probably, which series lands first in
mm-unstable should clean it up.
I would assume that Donet's series would go in first, such that you can
just reuse the helper from vm_utils.h
[1] https://lkml.kernel.org/r/20250804090410.of5xwrlker665bdp@master
Nothing else jumped at me
Acked-by: David Hildenbrand <david@redhat.com>
--
Cheers,
David / dhildenb
On 05/08/2025 11:30, David Hildenbrand wrote:
> On 04.08.25 17:40, Usama Arif wrote:
>> The test will set the global system THP setting to never, madvise
>> or always depending on the fixture variant and the 2M setting to
>> inherit before it starts (and reset to original at teardown).
>>
>> This tests if the process can:
>> - successfully set and get the policy to disable THPs completely.
>> - never get a hugepage when the THPs are completely disabled
>> with the prctl, including with MADV_HUGE and MADV_COLLAPSE.
>> - successfully reset the policy of the process.
>> - after reset, only get hugepages with:
>> - MADV_COLLAPSE when policy is set to never.
>> - MADV_HUGE and MADV_COLLAPSE when policy is set to madvise.
>> - always when policy is set to "always".
>> - repeat the above tests in a forked process to make sure
>> the policy is carried across forks.
>>
>> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
>> ---
>> tools/testing/selftests/mm/.gitignore | 1 +
>> tools/testing/selftests/mm/Makefile | 1 +
>> .../testing/selftests/mm/prctl_thp_disable.c | 173 ++++++++++++++++++
>> tools/testing/selftests/mm/thp_settings.c | 9 +-
>> tools/testing/selftests/mm/thp_settings.h | 1 +
>> 5 files changed, 184 insertions(+), 1 deletion(-)
>> create mode 100644 tools/testing/selftests/mm/prctl_thp_disable.c
>>
>> diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selftests/mm/.gitignore
>> index e7b23a8a05fe..eb023ea857b3 100644
>> --- a/tools/testing/selftests/mm/.gitignore
>> +++ b/tools/testing/selftests/mm/.gitignore
>> @@ -58,3 +58,4 @@ pkey_sighandler_tests_32
>> pkey_sighandler_tests_64
>> guard-regions
>> merge
>> +prctl_thp_disable
>> diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
>> index d13b3cef2a2b..2bb8d3ebc17c 100644
>> --- a/tools/testing/selftests/mm/Makefile
>> +++ b/tools/testing/selftests/mm/Makefile
>> @@ -86,6 +86,7 @@ TEST_GEN_FILES += on-fault-limit
>> TEST_GEN_FILES += pagemap_ioctl
>> TEST_GEN_FILES += pfnmap
>> TEST_GEN_FILES += process_madv
>> +TEST_GEN_FILES += prctl_thp_disable
>> TEST_GEN_FILES += thuge-gen
>> TEST_GEN_FILES += transhuge-stress
>> TEST_GEN_FILES += uffd-stress
>> diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c
>> new file mode 100644
>> index 000000000000..ef150180daf4
>> --- /dev/null
>> +++ b/tools/testing/selftests/mm/prctl_thp_disable.c
>> @@ -0,0 +1,173 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Basic tests for PR_GET/SET_THP_DISABLE prctl calls
>> + *
>> + * Author(s): Usama Arif <usamaarif642@gmail.com>
>> + */
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <string.h>
>> +#include <unistd.h>
>> +#include <sys/mman.h>
>> +#include <sys/prctl.h>
>> +#include <sys/wait.h>
>> +
>> +#include "../kselftest_harness.h"
>> +#include "thp_settings.h"
>> +#include "vm_util.h"
>> +
>> +static int sz2ord(size_t size, size_t pagesize)
>> +{
>> + return __builtin_ctzll(size / pagesize);
>> +}
>
> Note: We have this helper duplicated elsewhere (e.g., cow.c).
>
> See [1] how we're going to clean it up.
>
> Not sure how to resolve this. Probably, which series lands first in mm-unstable should clean it up.
>
> I would assume that Donet's series would go in first, such that you can just reuse the helper from vm_utils.h
>
> [1] https://lkml.kernel.org/r/20250804090410.of5xwrlker665bdp@master
>
>
> Nothing else jumped at me
>
> Acked-by: David Hildenbrand <david@redhat.com>
>
Thanks!
I will wait a few days and see if it has made it into mm-new and rebase and send the next revision.
>> >> Nothing else jumped at me >> >> Acked-by: David Hildenbrand <david@redhat.com> >> > > Thanks! > > I will wait a few days and see if it has made it into mm-new and rebase and send the next revision. Will only happen next week, after the merge windows is closed. @Donet, are you planning on re-submitting you series? -- Cheers, David / dhildenb
> +FIXTURE_SETUP(prctl_thp_disable_completely)
> +{
> + if (!thp_available())
> + SKIP(return, "Transparent Hugepages not available\n");
> +
> + self->pmdsize = read_pmd_pagesize();
> + if (!self->pmdsize)
> + SKIP(return, "Unable to read PMD size\n");
> +
> + thp_save_settings();
> + thp_read_settings(&self->settings);
> + self->settings.thp_enabled = variant->thp_policy;
> + self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
Oh, one more thing: should we set all other sizes also to THP_INHERIT or
(for simplicity) THP_NEVER?
--
Cheers,
David / dhildenb
On 05/08/2025 13:39, David Hildenbrand wrote:
>> +FIXTURE_SETUP(prctl_thp_disable_completely)
>> +{
>> + if (!thp_available())
>> + SKIP(return, "Transparent Hugepages not available\n");
>> +
>> + self->pmdsize = read_pmd_pagesize();
>> + if (!self->pmdsize)
>> + SKIP(return, "Unable to read PMD size\n");
>> +
>> + thp_save_settings();
>> + thp_read_settings(&self->settings);
>> + self->settings.thp_enabled = variant->thp_policy;
>> + self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
>
> Oh, one more thing: should we set all other sizes also to THP_INHERIT or (for simplicity) THP_NEVER?
>
hmm do we need to? I am hoping that we should always get the PMD size THP no matter what the policy
for others is in the scenario we have?
On 05.08.25 14:46, Usama Arif wrote:
>
>
> On 05/08/2025 13:39, David Hildenbrand wrote:
>>> +FIXTURE_SETUP(prctl_thp_disable_completely)
>>> +{
>>> + if (!thp_available())
>>> + SKIP(return, "Transparent Hugepages not available\n");
>>> +
>>> + self->pmdsize = read_pmd_pagesize();
>>> + if (!self->pmdsize)
>>> + SKIP(return, "Unable to read PMD size\n");
>>> +
>>> + thp_save_settings();
>>> + thp_read_settings(&self->settings);
>>> + self->settings.thp_enabled = variant->thp_policy;
>>> + self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
>>
>> Oh, one more thing: should we set all other sizes also to THP_INHERIT or (for simplicity) THP_NEVER?
>>
>
> hmm do we need to? I am hoping that we should always get the PMD size THP no matter what the policy
> for others is in the scenario we have?
Assuming 64K is set to "always", couldn't it mislead us in the
"madvise"/"never" test cases in some scenarios?
--
Cheers,
David / dhildenb
On 05/08/2025 13:55, David Hildenbrand wrote:
> On 05.08.25 14:46, Usama Arif wrote:
>>
>>
>> On 05/08/2025 13:39, David Hildenbrand wrote:
>>>> +FIXTURE_SETUP(prctl_thp_disable_completely)
>>>> +{
>>>> + if (!thp_available())
>>>> + SKIP(return, "Transparent Hugepages not available\n");
>>>> +
>>>> + self->pmdsize = read_pmd_pagesize();
>>>> + if (!self->pmdsize)
>>>> + SKIP(return, "Unable to read PMD size\n");
>>>> +
>>>> + thp_save_settings();
>>>> + thp_read_settings(&self->settings);
>>>> + self->settings.thp_enabled = variant->thp_policy;
>>>> + self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
>>>
>>> Oh, one more thing: should we set all other sizes also to THP_INHERIT or (for simplicity) THP_NEVER?
>>>
>>
>> hmm do we need to? I am hoping that we should always get the PMD size THP no matter what the policy
>> for others is in the scenario we have?
>
> Assuming 64K is set to "always", couldn't it mislead us in the "madvise"/"never" test cases in some scenarios?
>
I tried it with 64K to always and seems to be ok. check_huge_anon checks AnonHugepages from smaps which
only indicates the pmd mapped THPs only. So I think should be ok?
Happy to set them to never and the change is probably something simple like below (untested), but
just trying to understand better the need for it.
diff --git a/tools/testing/selftests/mm/prctl_thp_disable.c b/tools/testing/selftests/mm/prctl_thp_disable.c
index 4b072d4ecc30..ee692c397835 100644
--- a/tools/testing/selftests/mm/prctl_thp_disable.c
+++ b/tools/testing/selftests/mm/prctl_thp_disable.c
@@ -142,6 +142,8 @@ FIXTURE_SETUP(prctl_thp_disable_completely)
thp_save_settings();
thp_read_settings(&self->settings);
self->settings.thp_enabled = variant->thp_policy;
+ for (int i = 1; i < sz2ord(self->pmdsize, getpagesize()); i++)
+ self->settings.hugepages[i].enabled = THP_INHERIT;
self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
thp_write_settings(&self->settings);
}
@@ -244,6 +246,8 @@ FIXTURE_SETUP(prctl_thp_disable_except_madvise)
thp_save_settings();
thp_read_settings(&self->settings);
self->settings.thp_enabled = variant->thp_policy;
+ for (int i = 1; i < sz2ord(self->pmdsize, getpagesize()); i++)
+ self->settings.hugepages[i].enabled = THP_INHERIT;
self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
thp_write_settings(&self->settings);
}
[root@vm7 vmuser]# echo always > /sys/kernel/mm/transparent_hugepage/hugepages-64kB/enabled
[root@vm7 vmuser]# ./prctl_thp_disable
TAP version 13
1..12
# Starting 12 tests from 6 test cases.
# RUN prctl_thp_disable_completely.never.nofork ...
# OK prctl_thp_disable_completely.never.nofork
ok 1 prctl_thp_disable_completely.never.nofork
# RUN prctl_thp_disable_completely.never.fork ...
# OK prctl_thp_disable_completely.never.fork
ok 2 prctl_thp_disable_completely.never.fork
# RUN prctl_thp_disable_completely.madvise.nofork ...
# OK prctl_thp_disable_completely.madvise.nofork
ok 3 prctl_thp_disable_completely.madvise.nofork
# RUN prctl_thp_disable_completely.madvise.fork ...
# OK prctl_thp_disable_completely.madvise.fork
ok 4 prctl_thp_disable_completely.madvise.fork
# RUN prctl_thp_disable_completely.always.nofork ...
# OK prctl_thp_disable_completely.always.nofork
ok 5 prctl_thp_disable_completely.always.nofork
# RUN prctl_thp_disable_completely.always.fork ...
# OK prctl_thp_disable_completely.always.fork
ok 6 prctl_thp_disable_completely.always.fork
# RUN prctl_thp_disable_except_madvise.never.nofork ...
# OK prctl_thp_disable_except_madvise.never.nofork
ok 7 prctl_thp_disable_except_madvise.never.nofork
# RUN prctl_thp_disable_except_madvise.never.fork ...
# OK prctl_thp_disable_except_madvise.never.fork
ok 8 prctl_thp_disable_except_madvise.never.fork
# RUN prctl_thp_disable_except_madvise.madvise.nofork ...
# OK prctl_thp_disable_except_madvise.madvise.nofork
ok 9 prctl_thp_disable_except_madvise.madvise.nofork
# RUN prctl_thp_disable_except_madvise.madvise.fork ...
# OK prctl_thp_disable_except_madvise.madvise.fork
ok 10 prctl_thp_disable_except_madvise.madvise.fork
# RUN prctl_thp_disable_except_madvise.always.nofork ...
# OK prctl_thp_disable_except_madvise.always.nofork
ok 11 prctl_thp_disable_except_madvise.always.nofork
# RUN prctl_thp_disable_except_madvise.always.fork ...
# OK prctl_thp_disable_except_madvise.always.fork
ok 12 prctl_thp_disable_except_madvise.always.fork
# PASSED: 12 / 12 tests passed.
# Totals: pass:12 fail:0 xfail:0 xpass:0 skip:0 error:0
On 05.08.25 16:26, Usama Arif wrote:
>
>
> On 05/08/2025 13:55, David Hildenbrand wrote:
>> On 05.08.25 14:46, Usama Arif wrote:
>>>
>>>
>>> On 05/08/2025 13:39, David Hildenbrand wrote:
>>>>> +FIXTURE_SETUP(prctl_thp_disable_completely)
>>>>> +{
>>>>> + if (!thp_available())
>>>>> + SKIP(return, "Transparent Hugepages not available\n");
>>>>> +
>>>>> + self->pmdsize = read_pmd_pagesize();
>>>>> + if (!self->pmdsize)
>>>>> + SKIP(return, "Unable to read PMD size\n");
>>>>> +
>>>>> + thp_save_settings();
>>>>> + thp_read_settings(&self->settings);
>>>>> + self->settings.thp_enabled = variant->thp_policy;
>>>>> + self->settings.hugepages[sz2ord(self->pmdsize, getpagesize())].enabled = THP_INHERIT;
>>>>
>>>> Oh, one more thing: should we set all other sizes also to THP_INHERIT or (for simplicity) THP_NEVER?
>>>>
>>>
>>> hmm do we need to? I am hoping that we should always get the PMD size THP no matter what the policy
>>> for others is in the scenario we have?
>>
>> Assuming 64K is set to "always", couldn't it mislead us in the "madvise"/"never" test cases in some scenarios?
>>
>
> I tried it with 64K to always and seems to be ok. check_huge_anon checks AnonHugepages from smaps which
> only indicates the pmd mapped THPs only. So I think should be ok?
Ah, yes. If that's the case, then we can focus on PMD only and not care
about how the others are configured.
--
Cheers,
David / dhildenb
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