On Sun, Aug 09, 2026 at 11:03:35AM +0300, Mike Rapoport (Microsoft) wrote:
> Commit 49a4e7186b08 ("selftests/mm: thuge-gen: add setup of HugeTLB pages")
> changed thuge-gen test to use common functions for reading hugetlb
> attributes from sysfs, but it missed that the original read_free() function
> special cased PAGE_SIZE tests.
>
> For PAGE_SIZE tests, failure to read sysfs was ignored and read_free()
> returned 0.
>
> This allowed test_shmget() to essentially skip the check of how many huge
> pages was consumed when it ran with PAGE_SIZE.
>
> Commit 3199b0c09efa ("selftests/mm: fix read_file() return value check")
> fixed the common read_file() to actually return error on failure and this
> exposed the issue in test_shmget() that checks the number of free hugetlb
> pages even for PAGE_SIZE test, tries to access
>
> /sys/kernel/mm/hugepages/hugepages-<PAGE_SIZE>/free_hugepages
>
> and obviously fails there.
>
> Gate the checks for free huge pages on size != getpagesize() and initialize
> before and after variables to values matching PAGE_SIZE test.
>
> Fixes: 49a4e7186b08 ("selftests/mm: thuge-gen: add setup of HugeTLB pages")
> Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>With the issue Sarthak brought up addressed, LGTM, so: Acked-by: Lorenzo Stoakes (ARM) <[email protected]> > --- > selftests/mm: thuge-gen: fix test_shmget() for PAGE_SIZE check > --- > tools/testing/selftests/mm/thuge-gen.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/tools/testing/selftests/mm/thuge-gen.c > b/tools/testing/selftests/mm/thuge-gen.c > index 22b9c2f1c35d..50d0805b65db 100644 > --- a/tools/testing/selftests/mm/thuge-gen.c > +++ b/tools/testing/selftests/mm/thuge-gen.c > @@ -71,12 +71,16 @@ void test_mmap(unsigned long size, unsigned flags) > > void test_shmget(unsigned long size, unsigned flags) > { > - int id; > - unsigned long before, after; > + /* values for PAGE_SIZE test */ > + unsigned long before = NUM_PAGES; > + unsigned long after = 0; > struct shm_info i; > char *map; > + int id; > + > + if (size != getpagesize()) > + before = hugetlb_free_pages(size); > > - before = hugetlb_free_pages(size); > id = shmget(IPC_PRIVATE, size * NUM_PAGES, IPC_CREAT|0600|flags); > if (id < 0) { > if (errno == EPERM) { > @@ -97,10 +101,11 @@ void test_shmget(unsigned long size, unsigned flags) > shmctl(id, IPC_RMID, NULL); > > memset(map, 0xff, size*NUM_PAGES); > - after = hugetlb_free_pages(size); > + if (size != getpagesize()) > + after = hugetlb_free_pages(size); > > show(size); > - ksft_test_result(size == getpagesize() || (before - after) == NUM_PAGES, > + ksft_test_result((before - after) == NUM_PAGES, > "%s: mmap %lu %x\n", __func__, size, flags); > if (shmdt(map)) > ksft_exit_fail_msg("%s: shmdt: %s\n", __func__, > strerror(errno)); > > --- > base-commit: 17e5919bdca144d4e67337f53bf57d7811f62192 > change-id: 20260809-selftests-thuge-gen-fix-5ac05f56307c > > -- > Sincerely yours, > Mike. > -- Cheers, Lorenzo
