+ selftests-mincore-fix-tmpfs-mincore-test-failure.patch added to mm-hotfixes-unstable branch

+ selftests-mincore-fix-tmpfs-mincore-test-failure.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: selftests: mincore: fix tmpfs mincore test failure
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     selftests-mincore-fix-tmpfs-mincore-test-failure.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-mincore-fix-tmpfs-mincore-test-failure.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Baolin Wang <baolin.wang@linux.alibaba.com>
Subject: selftests: mincore: fix tmpfs mincore test failure
Date: Mon, 7 Apr 2025 19:31:35 +0800

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.

Link: https://lkml.kernel.org/r/9a00856cc6a8b4e46f4ab8b1af11ce5fc1a31851.1744025467.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mincore/mincore_selftest.c |   16 +----------
 1 file changed, 2 insertions(+), 14 deletions(-)

--- a/tools/testing/selftests/mincore/mincore_selftest.c~selftests-mincore-fix-tmpfs-mincore-test-failure
+++ a/tools/testing/selftests/mincore/mincore_selftest.c
@@ -286,8 +286,7 @@ out_free:
 
 /*
  * 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);
_

Patches currently in -mm which might be from baolin.wang@linux.alibaba.com are

selftests-mincore-fix-tmpfs-mincore-test-failure.patch