From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD49E1AB6F1; Fri, 5 Jun 2026 11:32:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780659122; cv=none; b=B+Uq99cdKPDNn1nwgZwQj8QM00qcrYaybJ8KXo+qEK0PLZ1V0nFDWIiqcsWR/F6nwwk/b4KttDuAfw3l8W+Y5B4oxRDavvI+4i/Eqw2twVLWwkr7ubuzxhWx13bZist6cnq9udKMs5lXPkyIsHR9Te232k3lpGFPpKUzYmdNAFQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780659122; c=relaxed/simple; bh=L8KMyoRzOG62/thuh9mBHzCevn2S+M9JoPnrBCKOMEI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qJbClaiz+2xnivFkIxrI8pAL67bDXoDR7DSs/DnQ2yvjVHgFZhI8BXKub6Y3+huvmQGpOzyV63ZEV4lED3QRHVnzhetvkktKVBQ2b543IDtNIRstvOlT7UfhiYGs/DJg0LOvB+3tEkAIQVwXEelSD/duMtj0NgScA9xwo5yOjHY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LpgVnwBS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LpgVnwBS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6FA61F00893; Fri, 5 Jun 2026 11:31:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780659120; bh=Fc9vcaYFGx4VJWN/qkM/ZED/XUOAhAtzfGEMOALwC10=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=LpgVnwBSDBMv2ZCVDsEcjfQRjXldbcrdFN6YWC0rquZ76JA4WLAVGYdrU2Hg0J0lu b9l48jH/dtdOxXSdPpiNOqWudkX7H+Dmk6Tu9z2LXgLyILK31qQOLW7KZ2lLLYAx3I fUYlaYaQdJ3iXTb1M1TogOngIKpo02yqpbd2QnvxpVH038t+JW9MFZDkhAV1DQCDii dOyl2XK8+BhGI4nDZpgsWPVpoFWUOyBIbuadfyTaVSYMIvySJTlLYbadUiM4xtF7KN 8RLN2HjeI1uJyOM2NAk8ouza4Wv8Bl+HS7G4okRB0cqcK7sKPLJJVHjh9v1hcoxnp2 dAjEYyWjWwq7A== Date: Fri, 5 Jun 2026 12:31:52 +0100 From: Lorenzo Stoakes To: Dev Jain Cc: akpm@linux-foundation.org, liam@infradead.org, jgg@ziepe.ca, leon@kernel.org, david@kernel.org, shuah@kernel.org, vbabka@kernel.org, jannh@google.com, pfalcato@suse.de, balbirs@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-kselftest@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, usama.arif@linux.dev Subject: Re: [PATCH v3 2/2] selftests/mm/hmm-tests: test pagemap reads of PMD device-private entries Message-ID: References: <20260604055308.1947679-1-dev.jain@arm.com> <20260604055308.1947679-3-dev.jain@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=us-ascii Content-Disposition: inline In-Reply-To: <20260604055308.1947679-3-dev.jain@arm.com> On Thu, Jun 04, 2026 at 05:53:06AM +0000, Dev Jain wrote: > To cover pagemap paths scanning PMD entries, add assertions to check > whether a device-private PMD entry has the correct pagemap information - > the PM_SWAP bit must be on in the pagemap entry. Before that, we must > assert through HMM_DMIRROR_SNAPSHOT snapshot that the leaf entry is > at PMD level and not PTE level. > > Signed-off-by: Dev Jain LGTM, and confirmed this triggers the issue locally so: Reviewed-by: Lorenzo Stoakes > --- > tools/testing/selftests/mm/hmm-tests.c | 34 ++++++++++++++++++++++++-- > 1 file changed, 32 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c > index e1c8a679a4cf3..46e0c8c921c3d 100644 > --- a/tools/testing/selftests/mm/hmm-tests.c > +++ b/tools/testing/selftests/mm/hmm-tests.c > @@ -2276,8 +2276,11 @@ TEST_F(hmm, migrate_anon_huge_fault) > unsigned long npages; > unsigned long size; > unsigned long i; > + unsigned char *m; > + uint64_t entry; > void *old_ptr; > void *map; > + int pagemap_fd; > int *ptr; > int ret; > > @@ -2300,8 +2303,6 @@ TEST_F(hmm, migrate_anon_huge_fault) > > npages = size >> self->page_shift; > map = (void *)ALIGN((uintptr_t)buffer->ptr, size); > - ret = madvise(map, size, MADV_HUGEPAGE); > - ASSERT_EQ(ret, 0); > old_ptr = buffer->ptr; > buffer->ptr = map; > > @@ -2309,6 +2310,9 @@ TEST_F(hmm, migrate_anon_huge_fault) > for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) > ptr[i] = i; > > + ret = madvise(map, size, MADV_COLLAPSE); > + ASSERT_EQ(ret, 0); > + > /* Migrate memory to device. */ > ret = hmm_migrate_sys_to_dev(self->fd, buffer, npages); > ASSERT_EQ(ret, 0); > @@ -2318,6 +2322,32 @@ TEST_F(hmm, migrate_anon_huge_fault) > for (i = 0, ptr = buffer->mirror; i < size / sizeof(*ptr); ++i) > ASSERT_EQ(ptr[i], i); > > + if (!hmm_is_coherent_type(variant->device_number)) { > + ret = hmm_dmirror_cmd(self->fd, HMM_DMIRROR_SNAPSHOT, > + buffer, npages); > + ASSERT_EQ(ret, 0); > + ASSERT_EQ(buffer->cpages, npages); > + > + m = buffer->mirror; > + for (i = 0; i < npages; ++i) > + ASSERT_EQ(m[i], HMM_DMIRROR_PROT_DEV_PRIVATE_LOCAL | > + HMM_DMIRROR_PROT_WRITE | > + HMM_DMIRROR_PROT_PMD); > + > + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); > + ASSERT_GE(pagemap_fd, 0); > + > + for (i = 0; i < npages; ++i) { > + entry = pagemap_get_entry(pagemap_fd, > + (char *)buffer->ptr + i * self->page_size); > + > + ASSERT_NE(entry & PM_SWAP, 0); > + ASSERT_FALSE(PAGEMAP_PRESENT(entry)); > + } > + > + close(pagemap_fd); > + } > + > /* Fault pages back to system memory and check them. */ > for (i = 0, ptr = buffer->ptr; i < size / sizeof(*ptr); ++i) > ASSERT_EQ(ptr[i], i); > -- > 2.43.0 >