[linux-2.6-block.git] / Documentation / mm / arch_pgtable_helpers.rst

.. SPDX-License-Identifier: GPL-2.0

.. _arch_page_table_helpers:

===============================
Architecture Page Table Helpers
===============================

Generic MM expects architectures (with MMU) to provide helpers to create, access
and modify page table entries at various level for different memory functions.
These page table helpers need to conform to a common semantics across platforms.
Following tables describe the expected semantics which can also be tested during
boot via CONFIG_DEBUG_VM_PGTABLE option. All future changes in here or the debug
test need to be in sync.


PTE Page Table Helpers
======================

+---------------------------+--------------------------------------------------+
| pte_same                  | Tests whether both PTE entries are the same      |
+---------------------------+--------------------------------------------------+
| pte_bad                   | Tests a non-table mapped PTE                     |
+---------------------------+--------------------------------------------------+
| pte_present               | Tests a valid mapped PTE                         |
+---------------------------+--------------------------------------------------+
| pte_young                 | Tests a young PTE                                |
+---------------------------+--------------------------------------------------+
| pte_dirty                 | Tests a dirty PTE                                |
+---------------------------+--------------------------------------------------+
| pte_write                 | Tests a writable PTE                             |
+---------------------------+--------------------------------------------------+
| pte_special               | Tests a special PTE                              |
+---------------------------+--------------------------------------------------+
| pte_protnone              | Tests a PROT_NONE PTE                            |
+---------------------------+--------------------------------------------------+
| pte_devmap                | Tests a ZONE_DEVICE mapped PTE                   |
+---------------------------+--------------------------------------------------+
| pte_soft_dirty            | Tests a soft dirty PTE                           |
+---------------------------+--------------------------------------------------+
| pte_swp_soft_dirty        | Tests a soft dirty swapped PTE                   |
+---------------------------+--------------------------------------------------+
| pte_mkyoung               | Creates a young PTE                              |
+---------------------------+--------------------------------------------------+
| pte_mkold                 | Creates an old PTE                               |
+---------------------------+--------------------------------------------------+
| pte_mkdirty               | Creates a dirty PTE                              |
+---------------------------+--------------------------------------------------+
| pte_mkclean               | Creates a clean PTE                              |
+---------------------------+--------------------------------------------------+
| pte_mkwrite               | Creates a writable PTE                           |
+---------------------------+--------------------------------------------------+
| pte_wrprotect             | Creates a write protected PTE                    |
+---------------------------+--------------------------------------------------+
| pte_mkspecial             | Creates a special PTE                            |
+---------------------------+--------------------------------------------------+
| pte_mkdevmap              | Creates a ZONE_DEVICE mapped PTE                 |
+---------------------------+--------------------------------------------------+
| pte_mksoft_dirty          | Creates a soft dirty PTE                         |
+---------------------------+--------------------------------------------------+
| pte_clear_soft_dirty      | Clears a soft dirty PTE                          |
+---------------------------+--------------------------------------------------+
| pte_swp_mksoft_dirty      | Creates a soft dirty swapped PTE                 |
+---------------------------+--------------------------------------------------+
| pte_swp_clear_soft_dirty  | Clears a soft dirty swapped PTE                  |
+---------------------------+--------------------------------------------------+
| pte_mknotpresent          | Invalidates a mapped PTE                         |
+---------------------------+--------------------------------------------------+
| ptep_clear                | Clears a PTE                                     |
+---------------------------+--------------------------------------------------+
| ptep_get_and_clear        | Clears and returns PTE                           |
+---------------------------+--------------------------------------------------+
| ptep_get_and_clear_full   | Clears and returns PTE (batched PTE unmap)       |
+---------------------------+--------------------------------------------------+
| ptep_test_and_clear_young | Clears young from a PTE                          |
+---------------------------+--------------------------------------------------+
| ptep_set_wrprotect        | Converts into a write protected PTE              |
+---------------------------+--------------------------------------------------+
| ptep_set_access_flags     | Converts into a more permissive PTE              |
+---------------------------+--------------------------------------------------+


PMD Page Table Helpers
======================

+---------------------------+--------------------------------------------------+
| pmd_same                  | Tests whether both PMD entries are the same      |
+---------------------------+--------------------------------------------------+
| pmd_bad                   | Tests a non-table mapped PMD                     |
+---------------------------+--------------------------------------------------+
| pmd_leaf                  | Tests a leaf mapped PMD                          |
+---------------------------+--------------------------------------------------+
| pmd_huge                  | Tests a HugeTLB mapped PMD                       |
+---------------------------+--------------------------------------------------+
| pmd_trans_huge            | Tests a Transparent Huge Page (THP) at PMD       |
+---------------------------+--------------------------------------------------+
| pmd_present               | Tests whether pmd_page() points to valid memory  |
+---------------------------+--------------------------------------------------+
| pmd_young                 | Tests a young PMD                                |
+---------------------------+--------------------------------------------------+
| pmd_dirty                 | Tests a dirty PMD                                |
+---------------------------+--------------------------------------------------+
| pmd_write                 | Tests a writable PMD                             |
+---------------------------+--------------------------------------------------+
| pmd_special               | Tests a special PMD                              |
+---------------------------+--------------------------------------------------+
| pmd_protnone              | Tests a PROT_NONE PMD                            |
+---------------------------+--------------------------------------------------+
| pmd_devmap                | Tests a ZONE_DEVICE mapped PMD                   |
+---------------------------+--------------------------------------------------+
| pmd_soft_dirty            | Tests a soft dirty PMD                           |
+---------------------------+--------------------------------------------------+
| pmd_swp_soft_dirty        | Tests a soft dirty swapped PMD                   |
+---------------------------+--------------------------------------------------+
| pmd_mkyoung               | Creates a young PMD                              |
+---------------------------+--------------------------------------------------+
| pmd_mkold                 | Creates an old PMD                               |
+---------------------------+--------------------------------------------------+
| pmd_mkdirty               | Creates a dirty PMD                              |
+---------------------------+--------------------------------------------------+
| pmd_mkclean               | Creates a clean PMD                              |
+---------------------------+--------------------------------------------------+
| pmd_mkwrite               | Creates a writable PMD                           |
+---------------------------+--------------------------------------------------+
| pmd_wrprotect             | Creates a write protected PMD                    |
+---------------------------+--------------------------------------------------+
| pmd_mkspecial             | Creates a special PMD                            |
+---------------------------+--------------------------------------------------+
| pmd_mkdevmap              | Creates a ZONE_DEVICE mapped PMD                 |
+---------------------------+--------------------------------------------------+
| pmd_mksoft_dirty          | Creates a soft dirty PMD                         |
+---------------------------+--------------------------------------------------+
| pmd_clear_soft_dirty      | Clears a soft dirty PMD                          |
+---------------------------+--------------------------------------------------+
| pmd_swp_mksoft_dirty      | Creates a soft dirty swapped PMD                 |
+---------------------------+--------------------------------------------------+
| pmd_swp_clear_soft_dirty  | Clears a soft dirty swapped PMD                  |
+---------------------------+--------------------------------------------------+
| pmd_mkinvalid             | Invalidates a mapped PMD [1]                     |
+---------------------------+--------------------------------------------------+
| pmd_set_huge              | Creates a PMD huge mapping                       |
+---------------------------+--------------------------------------------------+
| pmd_clear_huge            | Clears a PMD huge mapping                        |
+---------------------------+--------------------------------------------------+
| pmdp_get_and_clear        | Clears a PMD                                     |
+---------------------------+--------------------------------------------------+
| pmdp_get_and_clear_full   | Clears a PMD                                     |
+---------------------------+--------------------------------------------------+
| pmdp_test_and_clear_young | Clears young from a PMD                          |
+---------------------------+--------------------------------------------------+
| pmdp_set_wrprotect        | Converts into a write protected PMD              |
+---------------------------+--------------------------------------------------+
| pmdp_set_access_flags     | Converts into a more permissive PMD              |
+---------------------------+--------------------------------------------------+


PUD Page Table Helpers
======================

+---------------------------+--------------------------------------------------+
| pud_same                  | Tests whether both PUD entries are the same      |
+---------------------------+--------------------------------------------------+
| pud_bad                   | Tests a non-table mapped PUD                     |
+---------------------------+--------------------------------------------------+
| pud_leaf                  | Tests a leaf mapped PUD                          |
+---------------------------+--------------------------------------------------+
| pud_huge                  | Tests a HugeTLB mapped PUD                       |
+---------------------------+--------------------------------------------------+
| pud_trans_huge            | Tests a Transparent Huge Page (THP) at PUD       |
+---------------------------+--------------------------------------------------+
| pud_present               | Tests a valid mapped PUD                         |
+---------------------------+--------------------------------------------------+
| pud_young                 | Tests a young PUD                                |
+---------------------------+--------------------------------------------------+
| pud_dirty                 | Tests a dirty PUD                                |
+---------------------------+--------------------------------------------------+
| pud_write                 | Tests a writable PUD                             |
+---------------------------+--------------------------------------------------+
| pud_devmap                | Tests a ZONE_DEVICE mapped PUD                   |
+---------------------------+--------------------------------------------------+
| pud_mkyoung               | Creates a young PUD                              |
+---------------------------+--------------------------------------------------+
| pud_mkold                 | Creates an old PUD                               |
+---------------------------+--------------------------------------------------+
| pud_mkdirty               | Creates a dirty PUD                              |
+---------------------------+--------------------------------------------------+
| pud_mkclean               | Creates a clean PUD                              |
+---------------------------+--------------------------------------------------+
| pud_mkwrite               | Creates a writable PUD                           |
+---------------------------+--------------------------------------------------+
| pud_wrprotect             | Creates a write protected PUD                    |
+---------------------------+--------------------------------------------------+
| pud_mkdevmap              | Creates a ZONE_DEVICE mapped PUD                 |
+---------------------------+--------------------------------------------------+
| pud_mkinvalid             | Invalidates a mapped PUD [1]                     |
+---------------------------+--------------------------------------------------+
| pud_set_huge              | Creates a PUD huge mapping                       |
+---------------------------+--------------------------------------------------+
| pud_clear_huge            | Clears a PUD huge mapping                        |
+---------------------------+--------------------------------------------------+
| pudp_get_and_clear        | Clears a PUD                                     |
+---------------------------+--------------------------------------------------+
| pudp_get_and_clear_full   | Clears a PUD                                     |
+---------------------------+--------------------------------------------------+
| pudp_test_and_clear_young | Clears young from a PUD                          |
+---------------------------+--------------------------------------------------+
| pudp_set_wrprotect        | Converts into a write protected PUD              |
+---------------------------+--------------------------------------------------+
| pudp_set_access_flags     | Converts into a more permissive PUD              |
+---------------------------+--------------------------------------------------+


HugeTLB Page Table Helpers
==========================

+---------------------------+--------------------------------------------------+
| pte_huge                  | Tests a HugeTLB                                  |
+---------------------------+--------------------------------------------------+
| pte_mkhuge                | Creates a HugeTLB                                |
+---------------------------+--------------------------------------------------+
| huge_pte_dirty            | Tests a dirty HugeTLB                            |
+---------------------------+--------------------------------------------------+
| huge_pte_write            | Tests a writable HugeTLB                         |
+---------------------------+--------------------------------------------------+
| huge_pte_mkdirty          | Creates a dirty HugeTLB                          |
+---------------------------+--------------------------------------------------+
| huge_pte_mkwrite          | Creates a writable HugeTLB                       |
+---------------------------+--------------------------------------------------+
| huge_pte_wrprotect        | Creates a write protected HugeTLB                |
+---------------------------+--------------------------------------------------+
| huge_ptep_get_and_clear   | Clears a HugeTLB                                 |
+---------------------------+--------------------------------------------------+
| huge_ptep_set_wrprotect   | Converts into a write protected HugeTLB          |
+---------------------------+--------------------------------------------------+
| huge_ptep_set_access_flags  | Converts into a more permissive HugeTLB        |
+---------------------------+--------------------------------------------------+


SWAP Page Table Helpers
========================

+---------------------------+--------------------------------------------------+
| __pte_to_swp_entry        | Creates a swapped entry (arch) from a mapped PTE |
+---------------------------+--------------------------------------------------+
| __swp_to_pte_entry        | Creates a mapped PTE from a swapped entry (arch) |
+---------------------------+--------------------------------------------------+
| __pmd_to_swp_entry        | Creates a swapped entry (arch) from a mapped PMD |
+---------------------------+--------------------------------------------------+
| __swp_to_pmd_entry        | Creates a mapped PMD from a swapped entry (arch) |
+---------------------------+--------------------------------------------------+
| is_migration_entry        | Tests a migration (read or write) swapped entry  |
+-------------------------------+----------------------------------------------+
| is_writable_migration_entry   | Tests a write migration swapped entry        |
+-------------------------------+----------------------------------------------+
| make_readable_migration_entry | Creates a read migration swapped entry       |
+-------------------------------+----------------------------------------------+
| make_writable_migration_entry | Creates a write migration swapped entry      |
+-------------------------------+----------------------------------------------+

[1] https://lore.kernel.org/linux-mm/20181017020930.GN30832@redhat.com/
Commit	Line	Data
b1d00007 AK	1	.. SPDX-License-Identifier: GPL-2.0
	2
	3	.. _arch_page_table_helpers:
	4
	5	===============================
	6	Architecture Page Table Helpers
	7	===============================
	8
	9	Generic MM expects architectures (with MMU) to provide helpers to create, access
	10	and modify page table entries at various level for different memory functions.
	11	These page table helpers need to conform to a common semantics across platforms.
	12	Following tables describe the expected semantics which can also be tested during
	13	boot via CONFIG_DEBUG_VM_PGTABLE option. All future changes in here or the debug
	14	test need to be in sync.
	15
e01159c7	16
b1d00007 AK	17	PTE Page Table Helpers
	18	======================
	19
	20	+---------------------------+--------------------------------------------------+
	21	\| pte_same \| Tests whether both PTE entries are the same \|
	22	+---------------------------+--------------------------------------------------+
	23	\| pte_bad \| Tests a non-table mapped PTE \|
	24	+---------------------------+--------------------------------------------------+
	25	\| pte_present \| Tests a valid mapped PTE \|
	26	+---------------------------+--------------------------------------------------+
	27	\| pte_young \| Tests a young PTE \|
	28	+---------------------------+--------------------------------------------------+
	29	\| pte_dirty \| Tests a dirty PTE \|
	30	+---------------------------+--------------------------------------------------+
	31	\| pte_write \| Tests a writable PTE \|
	32	+---------------------------+--------------------------------------------------+
	33	\| pte_special \| Tests a special PTE \|
	34	+---------------------------+--------------------------------------------------+
	35	\| pte_protnone \| Tests a PROT_NONE PTE \|
	36	+---------------------------+--------------------------------------------------+
	37	\| pte_devmap \| Tests a ZONE_DEVICE mapped PTE \|
	38	+---------------------------+--------------------------------------------------+
	39	\| pte_soft_dirty \| Tests a soft dirty PTE \|
	40	+---------------------------+--------------------------------------------------+
	41	\| pte_swp_soft_dirty \| Tests a soft dirty swapped PTE \|
	42	+---------------------------+--------------------------------------------------+
	43	\| pte_mkyoung \| Creates a young PTE \|
	44	+---------------------------+--------------------------------------------------+
	45	\| pte_mkold \| Creates an old PTE \|
	46	+---------------------------+--------------------------------------------------+
	47	\| pte_mkdirty \| Creates a dirty PTE \|
	48	+---------------------------+--------------------------------------------------+
	49	\| pte_mkclean \| Creates a clean PTE \|
	50	+---------------------------+--------------------------------------------------+
	51	\| pte_mkwrite \| Creates a writable PTE \|
	52	+---------------------------+--------------------------------------------------+
bb5c47ce	53	\| pte_wrprotect \| Creates a write protected PTE \|
b1d00007 AK	54	+---------------------------+--------------------------------------------------+
	55	\| pte_mkspecial \| Creates a special PTE \|
	56	+---------------------------+--------------------------------------------------+
	57	\| pte_mkdevmap \| Creates a ZONE_DEVICE mapped PTE \|
	58	+---------------------------+--------------------------------------------------+
	59	\| pte_mksoft_dirty \| Creates a soft dirty PTE \|
	60	+---------------------------+--------------------------------------------------+
	61	\| pte_clear_soft_dirty \| Clears a soft dirty PTE \|
	62	+---------------------------+--------------------------------------------------+
	63	\| pte_swp_mksoft_dirty \| Creates a soft dirty swapped PTE \|
	64	+---------------------------+--------------------------------------------------+
	65	\| pte_swp_clear_soft_dirty \| Clears a soft dirty swapped PTE \|
	66	+---------------------------+--------------------------------------------------+
	67	\| pte_mknotpresent \| Invalidates a mapped PTE \|
	68	+---------------------------+--------------------------------------------------+
08d5b29e	69	\| ptep_clear \| Clears a PTE \|
b1d00007	70	+---------------------------+--------------------------------------------------+
08d5b29e PT	71	\| ptep_get_and_clear \| Clears and returns PTE \|
	72	+---------------------------+--------------------------------------------------+
	73	\| ptep_get_and_clear_full \| Clears and returns PTE (batched PTE unmap) \|
b1d00007 AK	74	+---------------------------+--------------------------------------------------+
	75	\| ptep_test_and_clear_young \| Clears young from a PTE \|
	76	+---------------------------+--------------------------------------------------+
	77	\| ptep_set_wrprotect \| Converts into a write protected PTE \|
	78	+---------------------------+--------------------------------------------------+
	79	\| ptep_set_access_flags \| Converts into a more permissive PTE \|
	80	+---------------------------+--------------------------------------------------+
	81
e01159c7	82
b1d00007 AK	83	PMD Page Table Helpers
	84	======================
	85
	86	+---------------------------+--------------------------------------------------+
	87	\| pmd_same \| Tests whether both PMD entries are the same \|
	88	+---------------------------+--------------------------------------------------+
	89	\| pmd_bad \| Tests a non-table mapped PMD \|
	90	+---------------------------+--------------------------------------------------+
	91	\| pmd_leaf \| Tests a leaf mapped PMD \|
	92	+---------------------------+--------------------------------------------------+
	93	\| pmd_huge \| Tests a HugeTLB mapped PMD \|
	94	+---------------------------+--------------------------------------------------+
	95	\| pmd_trans_huge \| Tests a Transparent Huge Page (THP) at PMD \|
	96	+---------------------------+--------------------------------------------------+
7ce5f7e1	97	\| pmd_present \| Tests whether pmd_page() points to valid memory \|
b1d00007 AK	98	+---------------------------+--------------------------------------------------+
	99	\| pmd_young \| Tests a young PMD \|
	100	+---------------------------+--------------------------------------------------+
	101	\| pmd_dirty \| Tests a dirty PMD \|
	102	+---------------------------+--------------------------------------------------+
	103	\| pmd_write \| Tests a writable PMD \|
	104	+---------------------------+--------------------------------------------------+
	105	\| pmd_special \| Tests a special PMD \|
	106	+---------------------------+--------------------------------------------------+
	107	\| pmd_protnone \| Tests a PROT_NONE PMD \|
	108	+---------------------------+--------------------------------------------------+
	109	\| pmd_devmap \| Tests a ZONE_DEVICE mapped PMD \|
	110	+---------------------------+--------------------------------------------------+
	111	\| pmd_soft_dirty \| Tests a soft dirty PMD \|
	112	+---------------------------+--------------------------------------------------+
	113	\| pmd_swp_soft_dirty \| Tests a soft dirty swapped PMD \|
	114	+---------------------------+--------------------------------------------------+
	115	\| pmd_mkyoung \| Creates a young PMD \|
	116	+---------------------------+--------------------------------------------------+
	117	\| pmd_mkold \| Creates an old PMD \|
	118	+---------------------------+--------------------------------------------------+
	119	\| pmd_mkdirty \| Creates a dirty PMD \|
	120	+---------------------------+--------------------------------------------------+
	121	\| pmd_mkclean \| Creates a clean PMD \|
	122	+---------------------------+--------------------------------------------------+
	123	\| pmd_mkwrite \| Creates a writable PMD \|
	124	+---------------------------+--------------------------------------------------+
bb5c47ce	125	\| pmd_wrprotect \| Creates a write protected PMD \|
b1d00007 AK	126	+---------------------------+--------------------------------------------------+
	127	\| pmd_mkspecial \| Creates a special PMD \|
	128	+---------------------------+--------------------------------------------------+
	129	\| pmd_mkdevmap \| Creates a ZONE_DEVICE mapped PMD \|
	130	+---------------------------+--------------------------------------------------+
	131	\| pmd_mksoft_dirty \| Creates a soft dirty PMD \|
	132	+---------------------------+--------------------------------------------------+
	133	\| pmd_clear_soft_dirty \| Clears a soft dirty PMD \|
	134	+---------------------------+--------------------------------------------------+
	135	\| pmd_swp_mksoft_dirty \| Creates a soft dirty swapped PMD \|
	136	+---------------------------+--------------------------------------------------+
	137	\| pmd_swp_clear_soft_dirty \| Clears a soft dirty swapped PMD \|
	138	+---------------------------+--------------------------------------------------+
	139	\| pmd_mkinvalid \| Invalidates a mapped PMD [1] \|
	140	+---------------------------+--------------------------------------------------+
	141	\| pmd_set_huge \| Creates a PMD huge mapping \|
	142	+---------------------------+--------------------------------------------------+
	143	\| pmd_clear_huge \| Clears a PMD huge mapping \|
	144	+---------------------------+--------------------------------------------------+
	145	\| pmdp_get_and_clear \| Clears a PMD \|
	146	+---------------------------+--------------------------------------------------+
	147	\| pmdp_get_and_clear_full \| Clears a PMD \|
	148	+---------------------------+--------------------------------------------------+
	149	\| pmdp_test_and_clear_young \| Clears young from a PMD \|
	150	+---------------------------+--------------------------------------------------+
	151	\| pmdp_set_wrprotect \| Converts into a write protected PMD \|
	152	+---------------------------+--------------------------------------------------+
	153	\| pmdp_set_access_flags \| Converts into a more permissive PMD \|
	154	+---------------------------+--------------------------------------------------+
	155
e01159c7	156
b1d00007 AK	157	PUD Page Table Helpers
	158	======================
	159
	160	+---------------------------+--------------------------------------------------+
	161	\| pud_same \| Tests whether both PUD entries are the same \|
	162	+---------------------------+--------------------------------------------------+
	163	\| pud_bad \| Tests a non-table mapped PUD \|
	164	+---------------------------+--------------------------------------------------+
	165	\| pud_leaf \| Tests a leaf mapped PUD \|
	166	+---------------------------+--------------------------------------------------+
	167	\| pud_huge \| Tests a HugeTLB mapped PUD \|
	168	+---------------------------+--------------------------------------------------+
	169	\| pud_trans_huge \| Tests a Transparent Huge Page (THP) at PUD \|
	170	+---------------------------+--------------------------------------------------+
	171	\| pud_present \| Tests a valid mapped PUD \|
	172	+---------------------------+--------------------------------------------------+
	173	\| pud_young \| Tests a young PUD \|
	174	+---------------------------+--------------------------------------------------+
	175	\| pud_dirty \| Tests a dirty PUD \|
	176	+---------------------------+--------------------------------------------------+
	177	\| pud_write \| Tests a writable PUD \|
	178	+---------------------------+--------------------------------------------------+
	179	\| pud_devmap \| Tests a ZONE_DEVICE mapped PUD \|
	180	+---------------------------+--------------------------------------------------+
	181	\| pud_mkyoung \| Creates a young PUD \|
	182	+---------------------------+--------------------------------------------------+
	183	\| pud_mkold \| Creates an old PUD \|
	184	+---------------------------+--------------------------------------------------+
	185	\| pud_mkdirty \| Creates a dirty PUD \|
	186	+---------------------------+--------------------------------------------------+
	187	\| pud_mkclean \| Creates a clean PUD \|
	188	+---------------------------+--------------------------------------------------+
	189	\| pud_mkwrite \| Creates a writable PUD \|
	190	+---------------------------+--------------------------------------------------+
bb5c47ce	191	\| pud_wrprotect \| Creates a write protected PUD \|
b1d00007 AK	192	+---------------------------+--------------------------------------------------+
	193	\| pud_mkdevmap \| Creates a ZONE_DEVICE mapped PUD \|
	194	+---------------------------+--------------------------------------------------+
	195	\| pud_mkinvalid \| Invalidates a mapped PUD [1] \|
	196	+---------------------------+--------------------------------------------------+
	197	\| pud_set_huge \| Creates a PUD huge mapping \|
	198	+---------------------------+--------------------------------------------------+
	199	\| pud_clear_huge \| Clears a PUD huge mapping \|
	200	+---------------------------+--------------------------------------------------+
	201	\| pudp_get_and_clear \| Clears a PUD \|
	202	+---------------------------+--------------------------------------------------+
	203	\| pudp_get_and_clear_full \| Clears a PUD \|
	204	+---------------------------+--------------------------------------------------+
	205	\| pudp_test_and_clear_young \| Clears young from a PUD \|
	206	+---------------------------+--------------------------------------------------+
	207	\| pudp_set_wrprotect \| Converts into a write protected PUD \|
	208	+---------------------------+--------------------------------------------------+
	209	\| pudp_set_access_flags \| Converts into a more permissive PUD \|
	210	+---------------------------+--------------------------------------------------+
	211
e01159c7	212
b1d00007 AK	213	HugeTLB Page Table Helpers
	214	==========================
	215
	216	+---------------------------+--------------------------------------------------+
	217	\| pte_huge \| Tests a HugeTLB \|
	218	+---------------------------+--------------------------------------------------+
	219	\| pte_mkhuge \| Creates a HugeTLB \|
	220	+---------------------------+--------------------------------------------------+
	221	\| huge_pte_dirty \| Tests a dirty HugeTLB \|
	222	+---------------------------+--------------------------------------------------+
	223	\| huge_pte_write \| Tests a writable HugeTLB \|
	224	+---------------------------+--------------------------------------------------+
	225	\| huge_pte_mkdirty \| Creates a dirty HugeTLB \|
	226	+---------------------------+--------------------------------------------------+
	227	\| huge_pte_mkwrite \| Creates a writable HugeTLB \|
	228	+---------------------------+--------------------------------------------------+
bb5c47ce	229	\| huge_pte_wrprotect \| Creates a write protected HugeTLB \|
b1d00007 AK	230	+---------------------------+--------------------------------------------------+
	231	\| huge_ptep_get_and_clear \| Clears a HugeTLB \|
	232	+---------------------------+--------------------------------------------------+
	233	\| huge_ptep_set_wrprotect \| Converts into a write protected HugeTLB \|
	234	+---------------------------+--------------------------------------------------+
	235	\| huge_ptep_set_access_flags \| Converts into a more permissive HugeTLB \|
	236	+---------------------------+--------------------------------------------------+
	237
e01159c7	238
b1d00007 AK	239	SWAP Page Table Helpers
	240	========================
	241
	242	+---------------------------+--------------------------------------------------+
	243	\| __pte_to_swp_entry \| Creates a swapped entry (arch) from a mapped PTE \|
	244	+---------------------------+--------------------------------------------------+
	245	\| __swp_to_pte_entry \| Creates a mapped PTE from a swapped entry (arch) \|
	246	+---------------------------+--------------------------------------------------+
	247	\| __pmd_to_swp_entry \| Creates a swapped entry (arch) from a mapped PMD \|
	248	+---------------------------+--------------------------------------------------+
	249	\| __swp_to_pmd_entry \| Creates a mapped PMD from a swapped entry (arch) \|
	250	+---------------------------+--------------------------------------------------+
	251	\| is_migration_entry \| Tests a migration (read or write) swapped entry \|
23647618 AK	252	+-------------------------------+----------------------------------------------+
	253	\| is_writable_migration_entry \| Tests a write migration swapped entry \|
	254	+-------------------------------+----------------------------------------------+
	255	\| make_readable_migration_entry \| Creates a read migration swapped entry \|
	256	+-------------------------------+----------------------------------------------+
	257	\| make_writable_migration_entry \| Creates a write migration swapped entry \|
	258	+-------------------------------+----------------------------------------------+
b1d00007 AK	259
b1d00007 AK	260	[1] https://lore.kernel.org/linux-mm/20181017020930.GN30832@redhat.com/