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 690B640B6E2; Thu, 27 Aug 2026 09:11:24 +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=1787821886; cv=none; b=OlZ33HBwQrysIkdQNZmCgI/lKorTm84Dv49xAZvlzykv2Ttb64Pbhg9aw+hm0WXh9kp4bVF4s5fZPcJKY4NPwB6sT5LjRo3mX5igFkta/Q8l+df0gvgiGt2dV0k0DmLXZUx9PyTVNz7rF7kdUJlaIgKZlA41h6+zE+6Hm3yZob0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787821886; c=relaxed/simple; bh=QKU+9q4pENcnompvJW0fhnGbUV8ZmvmR3+gMvGi7I0k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Rl5N+cXjmR2q15D0ODb8sl5PzG2DOqi2ZDxUyo1RQN84yUDqhkH0V8dnqcYQ3HBLMQr1m3Y2dKWUcljpgce07nkwhKIW7ZoxThjxGV/IOxvAMllpT5SCrgK+IdOCYePK1EO6dFMGUxvVu46vhzF9Aos3r+YC13M+2qB8JaC/dWo= 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=B78f3fUn; 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="B78f3fUn" 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 BAA691691; Thu, 27 Aug 2026 02:11:19 -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 F04703F66F; Thu, 27 Aug 2026 02:11:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1787821883; bh=QKU+9q4pENcnompvJW0fhnGbUV8ZmvmR3+gMvGi7I0k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=B78f3fUnTn4z7rhLL+do+CgyE8kOHsCC7k1NgDAp1/gfwIIO8Nh6AzoSw8HaJGJhM Fyq5N3VpBFcpwtbtozzYzAIyDnvbzPrNyZ30ZkXOdOKNLF7++7wUcq7q8tgo2022sl pMbahu2ZxtcFvFBT7bMpwqg4cTC1U5HPz+Vv0L/E= Date: Thu, 27 Aug 2026 10:11:18 +0100 From: Yeoreum Yun To: Baolin Wang Cc: Yeoreum Yun , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , "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 v2 2/2] kselftest: mm: replace usage of /proc/self/smaps for check_huge_xxx() helper Message-ID: References: <20260826-fix_split-v2-0-71153c7f579a@arm.com> <20260826-fix_split-v2-2-71153c7f579a@arm.com> <0107447a-7c1f-44f8-94fb-109b0f850677@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <0107447a-7c1f-44f8-94fb-109b0f850677@linux.alibaba.com> On Thu, Aug 27, 2026 at 04:28:01PM +0800, Baolin Wang wrote: > > > On 8/26/26 8:24 PM, 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. > > > > Reported-by: David Hildenbrand (Arm) > > Signed-off-by: Yeoreum Yun > > --- > > tools/testing/selftests/mm/vm_util.c | 130 ++++++++++++++++++++--------------- > > tools/testing/selftests/mm/vm_util.h | 1 + > > 2 files changed, 77 insertions(+), 54 deletions(-) > > > > diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c > > index 4821a3563036..1d0959b3b9e8 100644 > > --- a/tools/testing/selftests/mm/vm_util.c > > +++ b/tools/testing/selftests/mm/vm_util.c > > @@ -351,31 +351,13 @@ char *__get_smap_entry(void *addr, const char *pattern, char *buf, size_t len) > > return entry; > > } > > -static bool __check_pmd_huge(void *addr, char *pattern, int nr_hpages, > > - uint64_t hpage_size) > > -{ > > - char buffer[MAX_LINE_LENGTH]; > > - uint64_t thp = -1; > > - char *entry; > > - > > - entry = __get_smap_entry(addr, pattern, buffer, sizeof(buffer)); > > - if (!entry) > > - goto err_out; > > - > > - if (sscanf(entry, "%9" SCNu64 " kB", &thp) != 1) > > - ksft_exit_fail_msg("Reading smap error\n"); > > - > > -err_out: > > - return thp == (nr_hpages * (hpage_size >> 10)); > > -} > > - > > -static bool check_large_folios(void *addr, size_t len, int nr_hpages, > > - uint64_t hpage_size) > > +static bool check_large_folios(int pagemap_fd, int kpageflags_fd, > > + void *addr, size_t len, int nr_hpages, > > + uint64_t hpage_size) > > { > > int order = 0, pagesize = getpagesize(); > > unsigned int nr_pages = hpage_size / pagesize; > > int orders[MAX_NR_ORDERS], status; > > - int pagemap_fd, kpageflags_fd; > > bool ret = false; > > if (!nr_pages) > > @@ -386,15 +368,6 @@ static bool check_large_folios(void *addr, size_t len, int nr_hpages, > > ksft_exit_fail_msg("invalid order\n"); > > memset(orders, 0, sizeof(int) * MAX_NR_ORDERS); > > - pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); > > - if (pagemap_fd == -1) > > - ksft_exit_fail_msg("read pagemap fail\n"); > > - > > - kpageflags_fd = open(KPAGEFLAGS_PATH, O_RDONLY); > > - if (kpageflags_fd == -1) { > > - close(pagemap_fd); > > - ksft_exit_fail_msg("read kpageflags fail\n"); > > - } > > status = gather_folio_orders(addr, len, pagemap_fd, > > kpageflags_fd, orders, MAX_NR_ORDERS); > > @@ -405,48 +378,97 @@ static bool check_large_folios(void *addr, size_t len, int nr_hpages, > > ret = true; > > out: > > - close(pagemap_fd); > > - close(kpageflags_fd); > > return ret; > > } > > -bool check_huge_anon(void *addr, size_t len, int nr_hpages, uint64_t hpage_size) > > +enum check_huge_type { > > + CHECK_HUGE_ANON, > > + CHECK_HUGE_FILE, > > + CHECK_HUGE_SHMEM, > > +}; > > + > > +static bool __check_pmd_huge(void *addr, size_t len, int nr_hpages, > > + uint64_t hpage_size, enum check_huge_type type) > > The original __check_pmd_huge() is only for PMD-sized large folios, but now > it not only checks PMD-sized large folios but also mTHP large folios, which > I find confusing. Please keep its original semantics, and only check > PMD-sized large folios. Okay. thanks! > > { > > - uint64_t pmd_pagesize = read_pmd_pagesize(); > > + int pagemap_fd, kpageflags_fd; > > + uint64_t pmd_pagesize, granule; > > + uint64_t categories, kpf; > > + unsigned long pfn; > > + bool check_large, huge_mapped; > > + char *start = addr; > > + char *end = start + len; > > + pmd_pagesize = read_pmd_pagesize(); > > if (!pmd_pagesize) > > ksft_exit_fail_msg("reading PMD pagesize failed\n"); > > - if (hpage_size == pmd_pagesize) > > - return __check_pmd_huge(addr, "AnonHugePages: ", nr_hpages, hpage_size); > > + if (nr_hpages > 0) { > > + check_large = true; > > + granule = hpage_size; > > + } else { > > + check_large = false; > > + granule = psize(); > > + } > > This is incorrect for the mTHP large folio check. I already hit a selftest > failure. Please test your patches before sending them out. > > [root@]./khugepaged -c 4 mthp_khugepaged:anon > TAP version 13 > # Save THP and khugepaged settings... OK > 1..4 > # Allocate huge page on fault... OK > # Split huge PMD on MADV_DONTNEED... OK > ok 1 allocate on fault and split > # > # Run test: collapse_full (mthp_khugepaged:anon) > # Collapse multiple fully populated PTE table.... OK > ok 2 collapse_full > # > # Run test: collapse_empty (mthp_khugepaged:anon) > # Do not collapse empty PTE table.... OK > ok 3 collapse_empty > # > # Run test: collapse_single_mthp (mthp_khugepaged:anon) > # Collapse PTE table with half PTE entries present.... Fail > not ok 4 collapse_single_mthp > # Totals: pass:3 fail:1 xfail:0 xpass:0 skip:0 error:0 Oh sorry. I've forgotten to this case to test. Thanks! -- Sincerely, Yeoreum Yun