On 11/23/21 18:19, Yosry Ahmed wrote: > On Tue, Nov 23, 2021 at 5:08 PM Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote: >> >> On 11/23/21 12:46, Yosry Ahmed wrote: >>> The hugetlb vma mremap() test mentions in the header comment that it >>> uses 10MB worth of huge pages, when it actually uses 1GB. This causes >>> the test to fail on devices with smaller memories. >>> >>> Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx> >>> --- >>> tools/testing/selftests/vm/hugepage-mremap.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> I'll let Mina comment, but I think I know what happened. > > Thanks for taking the time to review this and explain what happened. > >> >> >> The original version of the test did indeed use 10MB. However, the mremap >> code must 'unshare' and shared pmd mappings before remapping. Since sharing >> requires mappings of at least 1GB, the size was changed to make sure unsharing >> worked. >> >> In the end, I believe I suggested adding hugepage-mremap to run_vmtests.sh. >> The script does not try to configure a GB worth of huge pages. And, I think >> it is somewhat unreasonable to suggest users gave a spare GB to run the test. > > Alternatively, we can pass an optional argument to the test that makes it use > 1GB instead of 10MB. This way, if the test is run with run_vmtests.sh the > default behavior would be to use 10MB, making sure users do not run out of > memory. Otherwise, an interested user could run the test without run_vmtest.sh > and provide the extra argument to make the test use 1GB and make sure that > unsharing works correctly. Thoughts? > Passing a 'mapping size' argument as you suggest would be best. That way run_vmtest.sh can pass in a size such as 10MB, but the test could be used independently with arbitrary size mappings. If you have the time to do this, go for it! -- Mike Kravetz
