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Message-ID: <61e36a73-2c8c-4897-9ba5-3b2d59f57b5d@redhat.com>
Date: Mon, 7 Apr 2025 17:04:42 +0200
From: David Hildenbrand <david@...hat.com>
To: Baolin Wang <baolin.wang@...ux.alibaba.com>, akpm@...ux-foundation.org,
hughd@...gle.com
Cc: willy@...radead.org, 21cnbao@...il.com, ryan.roberts@....com,
ziy@...dia.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] selftests: mincore: fix tmpfs mincore test failure
On 07.04.25 13:31, 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.
>
> As discussed with David, there's no reason to continue checking the readahead
> logic for tmpfs. Drop it to fix this issue.
>
BTW, should we add a Fixes: ? Could only be tmpfs support that changed
the behavior but didn't fixup the test case.
> Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> ---
> Changes from v1:
> - Drop the readahead logic check, per David.
> ---
> .../testing/selftests/mincore/mincore_selftest.c | 16 ++--------------
> 1 file changed, 2 insertions(+), 14 deletions(-)
>
> diff --git a/tools/testing/selftests/mincore/mincore_selftest.c b/tools/testing/selftests/mincore/mincore_selftest.c
> index e949a43a6145..0fd4b00bd345 100644
> --- a/tools/testing/selftests/mincore/mincore_selftest.c
> +++ b/tools/testing/selftests/mincore/mincore_selftest.c
> @@ -286,8 +286,7 @@ TEST(check_file_mmap)
>
> /*
> * Test mincore() behavior on a page backed by a tmpfs file. This test
> - * performs the same steps as the previous one. However, we don't expect
> - * any readahead in this case.
> + * performs the same steps as the previous one.
> */
> TEST(check_tmpfs_mmap)
> {
> @@ -298,7 +297,6 @@ TEST(check_tmpfs_mmap)
> int page_size;
> int fd;
> int i;
> - int ra_pages = 0;
>
> page_size = sysconf(_SC_PAGESIZE);
> vec_size = FILE_SIZE / page_size;
> @@ -341,8 +339,7 @@ TEST(check_tmpfs_mmap)
> }
>
> /*
> - * Touch a page in the middle of the mapping. We expect only
> - * that page to be fetched into memory.
> + * Touch a page in the middle of the mapping.
> */
> addr[FILE_SIZE / 2] = 1;
> retval = mincore(addr, FILE_SIZE, vec);
> @@ -351,15 +348,6 @@ TEST(check_tmpfs_mmap)
> TH_LOG("Page not found in memory after use");
> }
>
> - i = FILE_SIZE / 2 / page_size + 1;
> - while (i < vec_size && vec[i]) {
> - ra_pages++;
> - i++;
> - }
> - ASSERT_EQ(ra_pages, 0) {
> - TH_LOG("Read-ahead pages found in memory");
> - }
> -
> munmap(addr, FILE_SIZE);
> close(fd);
> free(vec);
Acked-by: David Hildenbrand <david@...hat.com>
--
Cheers,
David / dhildenb
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