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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 v8 2/4] kselftest: mm: replace usage of /proc/self/smaps for __check_pmd_huge() Message-ID: References: <20260924-fix_split-v8-0-cba7359d882a@arm.com> <20260924-fix_split-v8-2-cba7359d882a@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 14CE1140006 X-Stat-Signature: obe8m1feftxyzfsogcjpp4h1uo86jysm X-Rspam-User: X-HE-Tag: 1790346196-217965 X-HE-Meta: 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 khReRVyF 07+kMV/wzdi89rsou2k/elj/Uk2R9g+yZfgNjmoGsuarTb6QXYtUcppHVCBpbgdhLWsyoBpLjDo+9tTLceDTldytdUOJRfnKY75RYC49IMbZhFtjVCJdJC2+ibokDySNNK/vrFhp/k8wr3C5iOXyYPxb/VSdpddkKcDEkTMOBasHcGu2Tje2vbiSf9hV6wPMcMWwKOBsjej5mjIYGghQaDWiABoEvmd2mj7D+o2wQhWae1uSDkqcnEW1DU7o/pQgmUd2zFWLnMWZiet1VSY075Q11+1texjZdccnvqaWS4LLZ4TO/DaPxq9uPmbA8m4vDi7g3TpXZ6JT/+lfJx1xLiMHmRblbFp3XmJCAiE635vGi0XT15VJUtbqTGsiTRzaViljw4egcxXMp1bk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Sep 25, 2026 at 06:08:44PM +0530, Sarthak Sharma wrote: > > > On 9/25/26 12:41 AM, 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_pmd_huge() > > helpers incorrectly require the address returned by memalign() to > > match the VMA start address reported in /proc/self/smaps. > > > > Instead of relying on /proc/self/smaps, use /proc/self/pagemap and > > /proc/kpageflags to detect huge-page mappings checking PAGE_IS_HUGE > > and PAGE_IS_FILE accroding to type of huge page. > > s/accroding/according Okay. > > > > > Since shmem pages are also file-backed, simply check whether the page > > is file-backed. > > > > Fixes: 642bc52aed9 ("selftests: vm: bring common functions to a new file") > > Checkpatch gives a warning saying it requires atleast 12 characters of > commit SHA. Oops. I'll update. > > > Suggested-by: David Hildenbrand (Arm) > > Signed-off-by: Yeoreum Yun > > --- > > [...] > > > +static bool __check_pmd_huge(void *addr, size_t len, int nr_hpages, > > + uint64_t hpage_size, enum check_huge_type type) > > +{ > > + int pagemap_fd; > > + int nr_pmd_mappings = 0; > > + uint64_t categories; > > + char *start = addr; > > + char *end = start + len; > > + > > + pagemap_fd = open(PAGEMAP_PATH, O_RDONLY); > > + if (pagemap_fd < 0) > > + ksft_exit_fail_msg("open pagemap fail\n"); > > Can we use ksft_exit_fail_perror("open pagemap") here? Will help in > diagnosing failures as well. I see thanks! > > Apart from these nits, rest looks good. > > Reviewed-by: Sarthak Sharma -- Sincerely, Yeoreum Yun