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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 v3 2/2] kselftest: mm: replace usage of /proc/self/smaps for check_huge_xxx() helper Message-ID: References: <20260828-fix_split-v3-0-374022586a4b@arm.com> <20260828-fix_split-v3-2-374022586a4b@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: pu9mchew33irwkm66qaohkxxaf3uz75q X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: F338FC0008 X-Rspam-User: X-HE-Tag: 1787930545-840024 X-HE-Meta: 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 ZvsnHWKW gF7j1ewf9F8rxCE+nyrxTJsaFcRknRZ05C8FBPnnXPGsTuu/3QP75CLJEExG2Yg6BXk/Sxn+QUzWwDTWwsjl7miH+sLe7fI+etCDUqHPq8bB8/aZ8gIyATSK/g/DJGDQSqZVwZH4mA6dDDzP/RQTWbHjjkXRXz43rhlMn+ymXnCWDBd1kSg1P6i+CVNAuqdSf9ublqSrCXLbpTJDWrzI8b6lcjEkuc4kGwpYc+MS9so9HJXMNhyQJZ9aOKGncRUGt1nsowuU/TF4M159bVUESoExDSfaoHPYOCQIbNCfNxukdRTMAszrL0Lj0sS6q/HXwRdhp6b9/fP9sQR9ZE0QIVVGaweYjs3NJdHJIfUOOgB8P4dFhp9lENWPf9hw4win8IPZ0ah3AIStFh9Sls67/i7q/e/gqnSS6Swsy Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Aug 28, 2026 at 11:13:00AM -0400, Zi Yan wrote: > On Fri Aug 28, 2026 at 4:11 AM 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. > > > > Reported-by: David Hildenbrand (Arm) > > Suggested-by: Zi Yan > > Signed-off-by: Yeoreum Yun > > --- > > tools/testing/selftests/mm/vm_util.c | 145 ++++++++++++++++++++++------------- > > tools/testing/selftests/mm/vm_util.h | 1 + > > 2 files changed, 92 insertions(+), 54 deletions(-) > > > > diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c > > index 4821a3563036..083b72d92b14 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; > > } > > > > > > > + for (; start < end; start += scan_mapping_size) { > > + categories = pagemap_scan_get_categories(pagemap_fd, start); > > + pfn = pagemap_get_pfn(pagemap_fd, start); > > + if (pfn == -1UL) { > > + if (!allow_nonpresent) > > + goto out; > > + else > > + continue; > > + } > > + if (pageflags_get(pfn, kpageflags_fd, &kpf)) > > + ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno)); > > + if (check_pmd_mapping && (categories & PAGE_IS_HUGE)) > > + nr_pmd_mappings++; > > + if (kpf & KPF_COMPOUND_TAIL) > > + continue; > > + if (!check_huge_type(categories, kpf, type)) > > + goto out; > > + } > > + > > There is a trailing tab. > > > + if (check_pmd_mapping && (nr_pmd_mappings != nr_hpages)) > > + goto out; > > + ret = true; > > + > > +out: > > + close(pagemap_fd); > > + close(kpageflags_fd); > > + return ret; > > } > > > > Otherwise, LGTM. I assume the replacement of memalign(), from the > discussion between you and Lorenzo, will be added in a separate patch. > For this patch, Yeap. I'll post with the separated one. > > Reviewed-by: Zi Yan Thanks! -- Sincerely, Yeoreum Yun