Baolin Wang 7962e05a83 selftests: khugepaged: fix the shmem collapse failure ... When running the khugepaged selftest for shmem (./khugepaged all:shmem), I encountered the following test failures: : Run test: collapse_full (khugepaged:shmem) : Collapse multiple fully populated PTE table.... Fail : ... : Run test: collapse_single_pte_entry (khugepaged:shmem) : Collapse PTE table with single PTE entry present.... Fail : ... : Run test: collapse_full_of_compound (khugepaged:shmem) : Allocate huge page... OK : Split huge page leaving single PTE page table full of compound pages... OK : Collapse PTE table full of compound pages.... Fail The reason for the failure is that it will set MADV_NOHUGEPAGE to prevent khugepaged from continuing to scan shmem VMA after khugepaged finishes scanning in the wait_for_scan() function. Moreover, shmem requires a refault to establish PMD mappings. However, after commit 2b0f922323 ("mm: don't install PMD mappings when THPs are disabled by the hw/process/vma"), PMD mappings are prevented if the VMA is set with MADV_NOHUGEPAGE flag, so shmem cannot establish PMD mappings during refault. One way to fix this issue is to move the MADV_NOHUGEPAGE setting after the shmem refault. After shmem refault and check huge, the test case will unmap the shmem immediately. So it seems unnecessary to set the MADV_NOHUGEPAGE. Then we can simply drop the MADV_NOHUGEPAGE setting, and all khugepaged test cases passed. Link: https://lkml.kernel.org/r/d8502fc50d0304c2afd27ced062b1d636b7a872e.1749779183.git.baolin.wang@linux.alibaba.com Fixes: 2b0f922323 ("mm: don't install PMD mappings when THPs are disabled by the hw/process/vma") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dev Jain <dev.jain@arm.com> Tested-by: Dev Jain <dev.jain@arm.com> Tested-by: Mario Casquero <mcasquer@redhat.com> Cc: Barry Song <baohua@kernel.org> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Mariano Pache <npache@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>		2025-07-09 22:42:09 -07:00
..
crypto/chacha20-s390	crypto: lib/chacha - strongly type the ChaCha state	2025-05-12 13:32:53 +08:00
cxl	Merge branch 'for-6.16/cxl-features-ras' into cxl-for-next	2025-05-23 13:26:24 -07:00
fault-injection
ktest	ktest: Fix Test Failures Due to Missing LOG_FILE Directories	2025-03-27 09:34:00 -04:00
kunit	Revert "kunit: configs: Enable CONFIG_INIT_STACK_ALL_PATTERN in all_tests"	2025-06-03 11:20:21 +02:00
memblock	memblock: add MEMBLOCK_RSRV_KERN flag	2025-05-12 23:50:38 -07:00
nvdimm
radix-tree	maple_tree: add sufficient height	2025-05-11 17:48:29 -07:00
rbtree
scatterlist
selftests	selftests: khugepaged: fix the shmem collapse failure	2025-07-09 22:42:09 -07:00
shared	test suite: use %zu to print size_t	2025-04-11 17:32:35 -07:00
vma	mm: prevent KSM from breaking VMA merging for new VMAs	2025-07-09 22:41:54 -07:00
vsock	vsock/test: Add test for an unexpectedly lingering close()	2025-05-27 11:05:22 +02:00