Re: [PATCH 1/2] selftests: mincore: fix tmpfs mincore test failure

[Baolin Wang]

On 2025/3/27 22:36, Zi Yan wrote:
> On 25 Mar 2025, at 23:38, Baolin Wang wrote:
>
> > When running mincore test cases, I encountered the following failures:
> >
> > "
> > mincore_selftest.c:359:check_tmpfs_mmap:Expected ra_pages (511) == 0 (0)
> > mincore_selftest.c:360:check_tmpfs_mmap:Read-ahead pages found in memory
> > check_tmpfs_mmap: Test terminated by assertion
> >            FAIL  global.check_tmpfs_mmap
> > not ok 5 global.check_tmpfs_mmap
> > FAILED: 4 / 5 tests passed
> > "
> >
> > The reason for the test case failure is that my system automatically enabled
> > tmpfs large folio allocation by adding the 'transparent_hugepage_tmpfs=always'
> > cmdline. However, the test case still expects the tmpfs mounted on /dev/shm to
> > allocate small folios, which leads to assertion failures when verifying readahead
> > pages.
> >
> > To fix this issue, remount tmpfs to a new test directory and set the 'huge=never'
> > parameter to avoid allocating large folios, which can pass the test.
> >
> > Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> > ---
> >   .../selftests/mincore/mincore_selftest.c      | 25 +++++++++++++++++--
> >   1 file changed, 23 insertions(+), 2 deletions(-)
>
> <snip>
>
> >   	errno = 0;
> > -	fd = open("/dev/shm", O_TMPFILE | O_RDWR, 0600);
> > +	/* Do not use large folios for tmpfs mincore testing */
> > +	retval = mount("tmpfs", tmpfs_loc, "tmpfs", 0, "huge=never,size=4M");
> > +	ASSERT_EQ(0, retval) {
> > +		TH_LOG("Unable to mount tmpfs for testing\n");
> > +	}
> > +
> > +	retval = snprintf(testfile, INPUT_MAX, "%s/test_file", tmpfs_loc);
> > +	ASSERT_GE(INPUT_MAX, retval) {
> > +		TH_LOG("Unable to create a tmpfs for testing\n");
> > +	}
> > +
> > +	fd = open(testfile, O_CREAT|O_RDWR, 0664);
>
> The fd permission is changed from 0600 to 0664, but it probably does not
> matter.

It is just a temp file, so it doesn't matter.

> >   	ASSERT_NE(-1, fd) {
> >   		TH_LOG("Can't create temporary file: %s",
> >   			strerror(errno));
> > @@ -363,6 +382,8 @@ TEST(check_tmpfs_mmap)
> >   	munmap(addr, FILE_SIZE);
> >   	close(fd);
> >   	free(vec);
> > +	umount(tmpfs_loc);
> > +	rmdir(tmpfs_loc);
> >   }
> >
> >   TEST_HARNESS_MAIN
> > --
> > 2.43.5
>
> Otherwise, LGTM. Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>

Thanks for reviewing.