From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8D51E486BAE; Thu, 20 Aug 2026 21:27:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787261224; cv=none; b=u/a/rgT8rByIlmxRF50H492ymChjiEGfaX5crTqjJhV8WKJvqr+X8awSqDMa0GFIPzGrpkaGUsDfpWZCms0BHGzkjuMZho0wS3rVVy7duF1GqWLx96iNIpMgNTW1/Ts2cZLXX2WncyuSzm7HkwoRwom0Z4ZBSDtUFQ1K6i7Teyc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787261224; c=relaxed/simple; bh=GtZxJZ2uVfeF4rlVw6qybAWaJ/Pn2JPxWEnBFkpsqmA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=D5y+Dh3sX8pa944mPEDEKg7yhh69uxhuMfXV+rF4L4NoqFhmlhqUr6NApt3O99qstbJLSEY02+0BILYP2OJhFX6JkG/78d7wK6d0VEuCiBAt81FugJE4T1uuFKjI/iEVNSAydMiLeEyhfC6UZ0YRiJZvCtRI6fVSDYHm25Q6pck= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=QPDSeuHD; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="QPDSeuHD" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A757B202C; Thu, 20 Aug 2026 14:26:56 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D49923F763; Thu, 20 Aug 2026 14:26:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787261220; bh=GtZxJZ2uVfeF4rlVw6qybAWaJ/Pn2JPxWEnBFkpsqmA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QPDSeuHDSrpGU507oYLegehgj1gVzJa8qOPnvmiKgIYmXPt19bsNUNsaC8wFNCiSP 8ZvE88/GUEvv2MoMtV/TDPEfU77YEZm9CSQK7bb/PW21YKcHmSjBlZ4G2w3sNuhR2u warTFMqvZUikr8QuZG1iiiMQ8sz/zHEhMhBJUpog= Date: Thu, 20 Aug 2026 22:26:55 +0100 From: Yeoreum Yun To: Zi Yan Cc: Yeoreum Yun , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Kevin Brodsky , linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] kselftest: mm: replace usage of /proc/self/smaps for check_huge_xxx() helper Message-ID: References: <20260820-fix_split-v1-0-ab430c58c7cf@arm.com> <20260820-fix_split-v1-2-ab430c58c7cf@arm.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: > On Thu Aug 20, 2026 at 3:40 PM EDT, Yeoreum Yun wrote: > > Since glibc commit 321e1fc73f (“malloc: Enable 2MB THP by default on AArch64”), > > glibc may call madvise(MADV_HUGEPAGE) for sufficiently large allocations > > made by memalign(). > > > > The underlying VMA may start at a different address from the aligned > > address returned by memalign(). Furthermore, a subsequent > > madvise(MADV_HUGEPAGE) call does not split the VMA because the flag is > > already set. > > > > This causes split_huge_page_test to fail because the check_huge_xxx() > > helpers incorrectly require the address returned by memalign() to > > match the VMA start address reported in /proc/self/smaps. > > > > Fix this by using /proc/self/pagemap and /proc/kpageflags instead of > > /proc/self/smaps to detect huge pages and change the meaning of > > check_huge_xxx()'s nr_hpages argument: > > Have you checked Baolin's patches[1] in mm-new? They resue > gather_after_split_folio_orders() to reimplement check_huge_xxx(), also > based on pagemap and kpageflags. Does it fix the issue? > > [1] https://lore.kernel.org/all/cover.1785985999.git.baolin.wang@linux.alibaba.com/ > Unfortunately, No. since __check_pmd_huge() in check_huge_xxx() still use /proc/self/smaps [1] for pmd THP, it still has problem though ths patch series applied. [1] https://lore.kernel.org/all/56b16691f605426b33b5cf47319233de6127a6b3.1785985999.git.baolin.wang@linux.alibaba.com/ > > > > - nr_hpages > 0: check all of pages in the range are huge page. > > - nr_hpages < 0: check all of pages in the range are not huge page. > > - nr_hpages == 0: invalid. > > > > Reported-by: David Hildenbrand (Arm) > > Signed-off-by: Yeoreum Yun > > --- > > tools/testing/selftests/mm/khugepaged.c | 26 ++--- > > tools/testing/selftests/mm/split_huge_page_test.c | 6 +- > > tools/testing/selftests/mm/vm_util.c | 135 ++++++++++++++++++---- > > tools/testing/selftests/mm/vm_util.h | 1 + > > 4 files changed, 131 insertions(+), 37 deletions(-) > > > > > -- > Best Regards, > Yan, Zi > -- Sincerely, Yeoreum Yun