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Mon, 23 Jun 2025 18:43:36 +0000 (GMT) From: Gerald Schaefer To: Andrew Morton , Anshuman Khandual Cc: Matthew Wilcox , David Hildenbrand , LKML , linux-mm Subject: [RFC PATCH 1/1] mm/debug_vm_pgtable: Use a swp_entry_t input value for swap tests Date: Mon, 23 Jun 2025 20:43:21 +0200 Message-ID: <20250623184321.927418-2-gerald.schaefer@linux.ibm.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250623184321.927418-1-gerald.schaefer@linux.ibm.com> References: <20250623184321.927418-1-gerald.schaefer@linux.ibm.com> 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 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 9q4zn-EHraalKmcrE-a4FfMd3A3wfL6d X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNjIzMDExNSBTYWx0ZWRfX5C960XE696TI kPnUVNt6WE92bk4aF/81diAJP6DewyLRIbNBDj/tqEgB/9uXJfSE+mFIq9CPv/AOhnH+rgljdRW xEyWBOKnm5bebJMDR57zX3hc/pilZ2T0XNffcZs3cncIXrWgqQy39aom7L0kKL/1geO892cSMPY 75YR8FHmr6KaYHtRwd1EU3Ki9RDeqMENm92uQmNfE9qx4866gYgNsUVVmhcRBMK33rkw+rR/aBR SCdT7VRM78OUnK/8qQXI+Mvj0+5vAHU4EU/xrSCKm+jhyWmEzCAcgyNx9XB0RuAjJ+efi69AAQY Mh5EkdP/PjXCW267wI23/Fqd8bECxTMeIMdtdIa1I9tMYcrQKdXORXyYa8OYKeO2KVd+Drn84ic YpJuV/MtEJgI0UIvUH8PYeFgAOqFVc5pWAhOJIx0V8cBbTOV/Tw4p8g/K6VsjFP1h+n3ZJTC X-Authority-Analysis: v=2.4 cv=MshS63ae c=1 sm=1 tr=0 ts=6859a05b cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=6IFa9wvqVegA:10 a=VnNF1IyMAAAA:8 a=ZTx8QE4AkKJnx8U2w1UA:9 X-Proofpoint-GUID: 9q4zn-EHraalKmcrE-a4FfMd3A3wfL6d X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.7,FMLib:17.12.80.40 definitions=2025-06-23_05,2025-06-23_07,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 bulkscore=0 lowpriorityscore=0 spamscore=0 mlxlogscore=999 impostorscore=0 clxscore=1011 phishscore=0 malwarescore=0 suspectscore=0 adultscore=0 priorityscore=1501 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2506230115 Content-Type: text/plain; charset="utf-8" The various __pte/pmd_to_swp_entry and __swp_entry_to_pte/pmd helper functions are expected to operate on swapped PTE/PMD entries, not on present and mapped entries. Reflect this in the swap tests by using a swp_entry_t as input value, similar to how it is already done in pte_swap_exclusive_tests(). Move the swap entry creation to init_args() and store it in args, so it can also be used in other functions. The pte/pmd_swap_tests() are also changed to compare entries instead of pfn values, because pte/pmd_pfn() helpers are not expected to operate on swapped entries. E.g. on s390, pmd_pfn() needs different shifts for leaf (large) and non-leaf PMDs. Also update documentation, to reflect that the helpers operate on swapped and not mapped entries, and use correct names, i.e. __swp_to_pte/pmd_entry -> __swp_entry_to_pte/pmd. For consistency, also change pte/pmd_swap_soft_dirty_tests() to use args->swp_entry instead of a present and mapped PTE/PMD. Signed-off-by: Gerald Schaefer --- Documentation/mm/arch_pgtable_helpers.rst | 8 ++-- mm/debug_vm_pgtable.c | 55 ++++++++++++++--------- 2 files changed, 38 insertions(+), 25 deletions(-) diff --git a/Documentation/mm/arch_pgtable_helpers.rst b/Documentation/mm/a= rch_pgtable_helpers.rst index af245161d8e7..e2ac76202a85 100644 --- a/Documentation/mm/arch_pgtable_helpers.rst +++ b/Documentation/mm/arch_pgtable_helpers.rst @@ -242,13 +242,13 @@ SWAP Page Table Helpers =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 +---------------------------+---------------------------------------------= -----+ -| __pte_to_swp_entry | Creates a swapped entry (arch) from a mapped= PTE | +| __pte_to_swp_entry | Creates a swap entry (arch) from a swapped P= TE | +---------------------------+---------------------------------------------= -----+ -| __swp_to_pte_entry | Creates a mapped PTE from a swapped entry (a= rch) | +| __swp_entry_to_pte | Creates a swapped PTE from a swap entry (arc= h) | +---------------------------+---------------------------------------------= -----+ -| __pmd_to_swp_entry | Creates a swapped entry (arch) from a mapped= PMD | +| __pmd_to_swp_entry | Creates a swap entry (arch) from a swapped P= MD | +---------------------------+---------------------------------------------= -----+ -| __swp_to_pmd_entry | Creates a mapped PMD from a swapped entry (a= rch) | +| __swp_entry_to_pmd | Creates a swapped PMD from a swap entry (arc= h) | +---------------------------+---------------------------------------------= -----+ | is_migration_entry | Tests a migration (read or write) swapped en= try | +-------------------------------+-----------------------------------------= -----+ diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 7731b238b534..3b0f83ed6c2e 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -73,6 +73,8 @@ struct pgtable_debug_args { unsigned long fixed_pud_pfn; unsigned long fixed_pmd_pfn; unsigned long fixed_pte_pfn; + + swp_entry_t swp_entry; }; =20 static void __init pte_basic_tests(struct pgtable_debug_args *args, int id= x) @@ -754,12 +756,15 @@ static void __init pte_soft_dirty_tests(struct pgtabl= e_debug_args *args) =20 static void __init pte_swap_soft_dirty_tests(struct pgtable_debug_args *ar= gs) { - pte_t pte =3D pfn_pte(args->fixed_pte_pfn, args->page_prot); + pte_t pte; =20 if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)) return; =20 pr_debug("Validating PTE swap soft dirty\n"); + pte =3D swp_entry_to_pte(args->swp_entry); + WARN_ON(!is_swap_pte(pte)); + WARN_ON(!pte_swp_soft_dirty(pte_swp_mksoft_dirty(pte))); WARN_ON(pte_swp_soft_dirty(pte_swp_clear_soft_dirty(pte))); } @@ -793,7 +798,9 @@ static void __init pmd_swap_soft_dirty_tests(struct pgt= able_debug_args *args) return; =20 pr_debug("Validating PMD swap soft dirty\n"); - pmd =3D pfn_pmd(args->fixed_pmd_pfn, args->page_prot); + pmd =3D swp_entry_to_pmd(args->swp_entry); + WARN_ON(!is_swap_pmd(pmd)); + WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd))); WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd))); } @@ -804,17 +811,11 @@ static void __init pmd_swap_soft_dirty_tests(struct p= gtable_debug_args *args) { =20 static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *arg= s) { - unsigned long max_swap_offset; swp_entry_t entry, entry2; pte_t pte; =20 pr_debug("Validating PTE swap exclusive\n"); - - /* See generic_max_swapfile_size(): probe the maximum offset */ - max_swap_offset =3D swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entr= y(0, ~0UL)))); - - /* Create a swp entry with all possible bits set */ - entry =3D swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, max_swap_offset); + entry =3D args->swp_entry; =20 pte =3D swp_entry_to_pte(entry); WARN_ON(pte_swp_exclusive(pte)); @@ -838,30 +839,36 @@ static void __init pte_swap_exclusive_tests(struct pg= table_debug_args *args) =20 static void __init pte_swap_tests(struct pgtable_debug_args *args) { - swp_entry_t swp; - pte_t pte; + swp_entry_t entry, arch_entry; + pte_t pte, pte2; =20 pr_debug("Validating PTE swap\n"); - pte =3D pfn_pte(args->fixed_pte_pfn, args->page_prot); - swp =3D __pte_to_swp_entry(pte); - pte =3D __swp_entry_to_pte(swp); - WARN_ON(args->fixed_pte_pfn !=3D pte_pfn(pte)); + entry =3D args->swp_entry; + + pte =3D swp_entry_to_pte(entry); + WARN_ON(!is_swap_pte(pte)); + arch_entry =3D __pte_to_swp_entry(pte); + pte2 =3D __swp_entry_to_pte(arch_entry); + WARN_ON(memcmp(&pte, &pte2, sizeof(pte))); } =20 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION static void __init pmd_swap_tests(struct pgtable_debug_args *args) { - swp_entry_t swp; - pmd_t pmd; + swp_entry_t entry, arch_entry; + pmd_t pmd, pmd2; =20 if (!has_transparent_hugepage()) return; =20 pr_debug("Validating PMD swap\n"); - pmd =3D pfn_pmd(args->fixed_pmd_pfn, args->page_prot); - swp =3D __pmd_to_swp_entry(pmd); - pmd =3D __swp_entry_to_pmd(swp); - WARN_ON(args->fixed_pmd_pfn !=3D pmd_pfn(pmd)); + entry =3D args->swp_entry; + pmd =3D swp_entry_to_pmd(entry); + WARN_ON(!is_swap_pmd(pmd)); + + arch_entry =3D __pmd_to_swp_entry(pmd); + pmd2 =3D __swp_entry_to_pmd(arch_entry); + WARN_ON(memcmp(&pmd, &pmd2, sizeof(pmd))); } #else /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */ static void __init pmd_swap_tests(struct pgtable_debug_args *args) { } @@ -1166,6 +1173,7 @@ static void __init init_fixed_pfns(struct pgtable_deb= ug_args *args) =20 static int __init init_args(struct pgtable_debug_args *args) { + unsigned long max_swap_offset; struct page *page =3D NULL; int ret =3D 0; =20 @@ -1248,6 +1256,11 @@ static int __init init_args(struct pgtable_debug_arg= s *args) =20 init_fixed_pfns(args); =20 + /* See generic_max_swapfile_size(): probe the maximum offset */ + max_swap_offset =3D swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entr= y(0, ~0UL)))); + /* Create a swp entry with all possible bits set */ + args->swp_entry =3D swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, max_swap_of= fset); + /* * Allocate (huge) pages because some of the tests need to access * the data in the pages. The corresponding tests will be skipped --=20 2.48.1