On 13.08.25 20:52, Lorenzo Stoakes wrote:
On Wed, Aug 13, 2025 at 06:24:11PM +0200, David Hildenbrand wrote:
+
+FIXTURE_SETUP(prctl_thp_disable_except_madvise)
+{
+ 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");
+
+ if (prctl(PR_SET_THP_DISABLE, 1, PR_THP_DISABLE_EXCEPT_ADVISED, NULL, NULL))
+ SKIP(return, "Unable to set PR_THP_DISABLE_EXCEPT_ADVISED\n");
This should be a test fail I think, as the only ways this could fail are
invalid flags, or failure to obtain an mmap write lock.
Running a kernel that does not support it?
I can't see anything in the kernel to #ifdef it out so I suppose you mean
running these tests on an older kernel?
Yes.
But this is an unsupported way of running self-tests, they are tied to the
kernel version in which they reside, and test that specific version.
Unless I'm missing something here?
I remember we allow for a bit of flexibility when it is simple to handle.
Is that documented somewhere?
We could check the errno to distinguish I guess.
Which one? manpage says -EINVAL, but can also be due to incorrect invocation,
which would mean a typo could mean tests pass but your tests do nothing :)
Right, no ENOSYS in that case to distinguish :(
--
Cheers
David / dhildenb
