From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A765B47728F for ; Mon, 21 Sep 2026 21:18:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790025540; cv=none; b=fUGxC6En7pOoYnbg3nABGd7Sk6/eauU4/AmaawW4fzysT5uANVCSbP7U+PSMDmAuBlzvzPJLtdLxmieKQi8Ahf3/uq0vReYP4N1Z8D4lt4V7mzxVB13TT4vwj3Xf68JfvBf2rQwWaE7VCRPDtsc3OoE0+83WP4jadEYClkHO1JA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790025540; c=relaxed/simple; bh=AdvVPrWPzVqkx3sq+6nSLyIxFpdfYdJ/2aWUzwSe8m8=; h=Date:To:From:Subject:Message-Id; b=ezZHqSMMt5zBAZx6sMxaHIZPt9JG5V1ZkpWsoukCt2zpYchsP2o9lKPj4X7TiOC/SPStLoYrRXCC0lWDfYULQXsKi0qwnQMxliRrGoIj7jsiPLswIxX8X2A2ASJDKLVJISwTQUXRRKhAhr/X6uzlpLaqvkyrEeDX3fqVURbrueM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=WjdSeqeo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="WjdSeqeo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29BE31F00893; Mon, 21 Sep 2026 21:18:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1790025538; bh=kZhmNuaPEiLW0AArvRHUDUogxvsM4UQDNj5lgerJNaM=; h=Date:To:From:Subject; b=WjdSeqeosnsFF33kL2vEaeUAu8ZBkr0AyIiV2kyiFJeDCfjeGAY3G0/GHsDe8OEhQ olObOhkjBOYLGeaUPZUEhbLalXCPfGMcbRc5vRJ0WufalKNOhcIZIGidatsSi7wy/l 4FkPeoCRS/iBfFtDiAISzfUm1MVkbMZGXwjmrLFg= Date: Mon, 21 Sep 2026 14:18:57 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,vbabka@kernel.org,usama.arif@linux.dev,surenb@google.com,shuah@kernel.org,ryan.roberts@arm.com,rppt@kernel.org,nico.pache@linux.dev,mhocko@suse.com,ljs@kernel.org,liam@infradead.org,lance.yang@linux.dev,kas@kernel.org,dev.jain@arm.com,david@kernel.org,baolin.wang@linux.alibaba.com,baohua@kernel.org,yeoreum.yun@arm.com,akpm@linux-foundation.org From: Andrew Morton Subject: + kselftest-mm-fix-intermittent-failure-khugepaged-test.patch added to mm-new branch Message-Id: <20260921211858.29BE31F00893@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: kselftest: mm: fix intermittent failure khugepaged test has been added to the -mm mm-new branch. Its filename is kselftest-mm-fix-intermittent-failure-khugepaged-test.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kselftest-mm-fix-intermittent-failure-khugepaged-test.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Yeoreum Yun Subject: kselftest: mm: fix intermittent failure khugepaged test Date: Mon, 21 Sep 2026 11:35:02 +0100 There are intermittent failures in collapse_max_ptes_swap() and collapse_max_ptes_shared() when using the khugepaged_context: // while running ./khugepaged -s 2 # Run test: collapse_max_ptes_shared (khugepaged:anon) # Allocate huge page... OK # Share huge page over fork()... OK # Trigger CoW on page 1023 of 2048... OK # Maybe collapse with max_ptes_shared exceeded.... OK # Trigger CoW on page 1024 of 2048... Fail Bail out! Unexpected huge page # Planned tests != run tests (26 != 23) # Totals: pass:23 fail:0 xfail:0 xpass:0 skip:0 error:0 # Run test: collapse_max_ptes_swap (khugepaged:anon) # Swapout 257 of 2048 pages... OK # Maybe collapse with max_ptes_swap exceeded.... OK # Swapout 256 of 2048 pages... OK Bail out! Unexpected huge page # Planned tests != run tests (26 != 17) # Totals: pass:17 fail:0 xfail:0 xpass:0 skip:0 error:0 This happens because khugepaged may collapse the pages before wait_for_scan() is called, causing a sanity check that expects uncollapsed pages to fail. For example, in collapse_max_ptes_swap(), after faulting the pages back in and paging out up to max_ptes_swap pages, khugepaged may collapse them again before c->collapse() is called. To prevent this, mark the VMA with MADV_NOHUGEPAGE after it has been collapsed by wait_for_scan() for anon. This prevents khugepaged from collapsing it again before c->collapse() is called. This failure was observed on NVIDIA Spark with 16KB page. Link: https://lore.kernel.org/20260921-fix_khugepagd_fail-v2-2-3c2877beef61@arm.com Signed-off-by: Yeoreum Yun Signed-off-by: Andrew Morton Cc: Zi Yan Cc: Baolin Wang Cc: Liam Howlett Cc: Nico Pache (Red Hat) Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lance Yang Cc: Usama Arif Cc: Kirill A. Shutemov Cc: Lorenzo Stoakes (ARM) Cc: "Vlastimil Babka (SUSE)" Cc: "Mike Rapoport (IBM)" Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: David Hildenbrand (ARM) Cc: Shuah Khan (Samsung OSG) --- tools/testing/selftests/mm/khugepaged.c | 3 +++ 1 file changed, 3 insertions(+) --- a/tools/testing/selftests/mm/khugepaged.c~kselftest-mm-fix-intermittent-failure-khugepaged-test +++ a/tools/testing/selftests/mm/khugepaged.c @@ -618,6 +618,9 @@ static bool wait_for_scan(const char *ms usleep(TICK); } + if (!strncmp(ops->name, "anon", 4)) + madvise(p, len, MADV_NOHUGEPAGE); + return timeout == -1; } _ Patches currently in -mm which might be from yeoreum.yun@arm.com are kselftest-mm-fix-potential-failure-for-merged-vma-in-guard-regions.patch kselftest-mm-remove-exclusion-of-building-soft-dirty-test-in-arm64.patch kselftest-mm-return-fail-when-child-test-result-is-fail-in-khugepaged.patch kselftest-mm-fix-intermittent-failure-khugepaged-test.patch