From nobody Mon Jun 8 12:11:54 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id DBE473BB9E0; Fri, 29 May 2026 11:17:18 +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=1780053440; cv=none; b=Ox0sP5vmOKjmfOIaDi6vEPdza0il+2C9MgtK5fz7PGqGjsts1/PUxoBqfC7RibwCZv9Zx2ZWCEx83lU6k5k70DH3z6dR7bAUVaW3eV2pZ8+ItSaeNqZHm3qF31eYx5F1idHVU/ZvNVJVBOi1MAupZgAgC8W0pcTrZEC/SWV2RSg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780053440; c=relaxed/simple; bh=cx9bkGJ2eDRyMtzNNbeuK1dl0e/7tAqg3VyKX3JjrwQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=MgD4Byx5vPAUnZMrxoXLDhTXGlJvcyQ/dEKUaCNMpZCyGLPX/iEp4mUJirs+jAg60WdqTfh99MKq1yUHrQzR5QHZyvBq3ZREdkz/o+YkrwYRUJDhR3pbfUA9m/3vuRZ9Up2zdybatxyTJ7FsGvy5aYBYW1lHK+2Cbf9cKmQFnRI= 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=cmig+QQR; 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="cmig+QQR" 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 40F072247; Fri, 29 May 2026 04:17:13 -0700 (PDT) Received: from cesw-amp-gbt-1s-m12830-01.blr.arm.com (cesw-amp-gbt-1s-m12830-01.blr.arm.com [10.164.195.31]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 30ED13F905; Fri, 29 May 2026 04:17:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1780053438; bh=cx9bkGJ2eDRyMtzNNbeuK1dl0e/7tAqg3VyKX3JjrwQ=; h=From:To:Cc:Subject:Date:From; b=cmig+QQRNEziskriXoC4pzo9VhXrb3OFQb0apJK+kRtxnbwjtcgcZktmT193CNieV 233HUHFvMNrJwFG/lOUU41/ZbqMDIhECIBUhNb4/7jDeCbDbnGLyA22ih+GePPa+Eg Ycwv0YyxmHAIdnPjbSWPowjJt+L/O73CN84pDsuM= From: Dev Jain To: akpm@linux-foundation.org, liam@infradead.org, ljs@kernel.org, jgg@ziepe.ca, leon@kernel.org, david@kernel.org, shuah@kernel.org Cc: Dev Jain , vbabka@kernel.org, jannh@google.com, pfalcato@suse.de, rppt@kernel.org, surenb@google.com, mhocko@suse.com, balbirs@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: [PATCH] fs/proc/task_mmu: do not warn on seeing non-migration pmd entry Date: Fri, 29 May 2026 11:17:03 +0000 Message-ID: <20260529111704.1078346-1-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" pagemap_pmd_range_thp() warns if a non-present PMD is not a migration entry. This became false once device-private entries at the PMD level were added. One can hit the warning by patching hmm-tests.c with the following: diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftes= ts/mm/hmm-tests.c index e1c8a679a4cf3..7f0a3384f3c5f 100644 Acked-by: David Hildenbrand (Arm) Reviewed-by: Oscar Salvador (SUSE) --- a/tools/testing/selftests/mm/hmm-tests.c +++ b/tools/testing/selftests/mm/hmm-tests.c @@ -209,6 +209,37 @@ static int hmm_dmirror_cmd(int fd, return 0; } +static int hmm_read_self_pagemap(void *addr, unsigned long npages, + unsigned long page_size) +{ + const size_t entry_size =3D sizeof(uint64_t); + const off_t offset =3D ((uintptr_t)addr / page_size) * entry_size; + uint64_t *entries; + ssize_t nread; + int fd; + + entries =3D malloc(npages * entry_size); + if (!entries) + return -ENOMEM; + + fd =3D open("/proc/self/pagemap", O_RDONLY); + if (fd < 0) { + free(entries); + return -errno; + } + + nread =3D pread(fd, entries, npages * entry_size, offset); + close(fd); + free(entries); + + if (nread < 0) + return -errno; + if ((size_t)nread !=3D npages * entry_size) + return -EIO; + + return 0; +} + static void hmm_buffer_free(struct hmm_buffer *buffer) { if (buffer =3D=3D NULL) @@ -2314,6 +2345,10 @@ TEST_F(hmm, migrate_anon_huge_fault) ASSERT_EQ(ret, 0); ASSERT_EQ(buffer->cpages, npages); + /* Exercise pagemap on a PMD device-private entry. */ + ret =3D hmm_read_self_pagemap(buffer->ptr, npages, self->page_size); + ASSERT_EQ(ret, 0); + /* Check what the device read. */ for (i =3D 0, ptr =3D buffer->mirror; i < size / sizeof(*ptr); ++i) ASSERT_EQ(ptr[i], i); Therefore, remove the stale migration-only assertion. Fixes: a30b48bf1b24 ("mm/migrate_device: implement THP migration of zone de= vice pages") Cc: stable@vger.kernel.org Signed-off-by: Dev Jain --- Applies on mm-unstable (404fb4f38e8f). fs/proc/task_mmu.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 1e3a15bf46f4e..58938e62154d9 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -2129,7 +2129,6 @@ static int pagemap_pmd_range_thp(pmd_t *pmdp, unsigne= d long addr, flags |=3D PM_SOFT_DIRTY; if (pmd_swp_uffd_wp(pmd)) flags |=3D PM_UFFD_WP; - VM_WARN_ON_ONCE(!pmd_is_migration_entry(pmd)); page =3D softleaf_to_page(entry); } =20 --=20 2.43.0