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 4328317993; Fri, 21 Aug 2026 00:26:53 +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=1787272014; cv=none; b=Hx3uM1/i8ajuYRURMGp8PG4Z4DeipCYa25oTzfa3RbIxMSA+bKFACfE5KhArURxwOipWEJpjKRypUEVtTDdmbV1GB0A3uKj6oy4Uk36JeejiuJSKT6PorvzYKVJ77PrdHyOpVQly4plX1RDAY1Dt7O8+ntig30+CdCXjsvA1VV8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787272014; c=relaxed/simple; bh=rZtzriMNQLdFVOWizIVfqbKh0as8DbXMCiKrEQ8ecIY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=vBJQ6YAwXZCuVobqEuoHrlfKFUszfnu1wyPi0Dntug+KlDDkggnlFS4/mehGMbPpyZDMXrkD1kkI1HnywL/FhpEfrCCF4GJcc/yRU0qlcxIswkT7BQPn91D+QS7ACsAZzjJkGoTWhWr/+Co8rIloEI2jSczxfz+kUbhK6fHCz+c= 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=OpB9Z52b; 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="OpB9Z52b" 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 4AC33202C; Thu, 20 Aug 2026 17:26:48 -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 7778D3F66F; Thu, 20 Aug 2026 17:26:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787272012; bh=rZtzriMNQLdFVOWizIVfqbKh0as8DbXMCiKrEQ8ecIY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OpB9Z52bMX+u/hTZY2vChYPYCd1qlV0jQCF3mgYzesh4wViGlYG6Xl+gbXqySp7JR eqW0aDi78KPuR2W5srPpKsUWliPqtXW1gSVewlxs+004FHq/Tj48UKbjcRsM0qHqB9 BTaElZfW9yVhKEGypc9R+7NE8wX4L1Lr4rtjNMwg= Date: Fri, 21 Aug 2026 01:26:47 +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 08:09:12PM -0400, Zi Yan wrote: > On Thu Aug 20, 2026 at 5:26 PM EDT, Yeoreum Yun wrote: > >> 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(). > > I just googled the commit and find that Dev did that. ;) > > >> > > >> > 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/ > > In that case, is it possible to use and extend check_large_folios() for > all check_huge_xxx()? You still need pagemap_scan_get_categories() to > check PAGE_IS_HUGE to identify huge mappings. Or at least > check_huge_xxx() in your patch can share most of the code. Agree. but TBH, I think check_large_folios() can replace checking PAGE_IS_HUGE and keep the later part to check wehther PAGE_IS_FILE and SWAPBACKED according to check_huge_xxx(). BTW, Should I do this after [1] is merged into mm-unstable? > BTW, in your check_huge_shmem(), expect_huge seems to be inverted > compared to other check_huge_xxx(). Yes. I've noticed. this was my typo while I change the variable name... Thanks! [1] https://lore.kernel.org/all/cover.1785985999.git.baolin.wang@linux.alibaba.com/ > > -- > Best Regards, > Yan, Zi > -- Sincerely, Yeoreum Yun