| Message ID | c7026449473790e2844bb82012216c57047c7639.1725941415.git-series.apopple@nvidia.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | fs/dax: Fix FS DAX page reference counts | expand |
On Tue, Sep 10, 2024 at 02:14:29PM +1000, Alistair Popple wrote: > @@ -337,6 +341,7 @@ struct folio { > /* private: */ > }; > /* public: */ > + struct dev_pagemap *pgmap; Shouldn't that be indented by one more tab stop? And for ease of reading, perhaps it should be placed either immediately before or after 'struct list_head lru;'? > +++ b/include/linux/mmzone.h > @@ -1134,6 +1134,12 @@ static inline bool is_zone_device_page(const struct page *page) > return page_zonenum(page) == ZONE_DEVICE; > } > > +static inline struct dev_pagemap *page_dev_pagemap(const struct page *page) > +{ > + WARN_ON(!is_zone_device_page(page)); > + return page_folio(page)->pgmap; > +} I haven't read to the end yet, but presumably we'll eventually want: static inline struct dev_pagemap *folio_dev_pagemap(const struct folio *folio) { WARN_ON(!folio_is_zone_device(folio)) return folio->pgmap; } and since we'll want it eventually, maybe now is the time to add it, and make page_dev_pagemap() simply call it?
Matthew Wilcox <willy@infradead.org> writes: > On Tue, Sep 10, 2024 at 02:14:29PM +1000, Alistair Popple wrote: >> @@ -337,6 +341,7 @@ struct folio { >> /* private: */ >> }; >> /* public: */ >> + struct dev_pagemap *pgmap; > > Shouldn't that be indented by one more tab stop? > > And for ease of reading, perhaps it should be placed either immediately > before or after 'struct list_head lru;'? > >> +++ b/include/linux/mmzone.h >> @@ -1134,6 +1134,12 @@ static inline bool is_zone_device_page(const struct page *page) >> return page_zonenum(page) == ZONE_DEVICE; >> } >> >> +static inline struct dev_pagemap *page_dev_pagemap(const struct page *page) >> +{ >> + WARN_ON(!is_zone_device_page(page)); >> + return page_folio(page)->pgmap; >> +} > > I haven't read to the end yet, but presumably we'll eventually want: > > static inline struct dev_pagemap *folio_dev_pagemap(const struct folio *folio) > { > WARN_ON(!folio_is_zone_device(folio)) > return folio->pgmap; > } > > and since we'll want it eventually, maybe now is the time to add it, > and make page_dev_pagemap() simply call it? Sounds reasonable. I had open-coded folio->pgmap where it's needed because at those points it's "obviously" a ZONE_DEVICE folio. Will add it.
On Tue, Sep 10, 2024 at 04:57:41PM +1000, Alistair Popple wrote: > > Matthew Wilcox <willy@infradead.org> writes: > > > On Tue, Sep 10, 2024 at 02:14:29PM +1000, Alistair Popple wrote: > >> @@ -337,6 +341,7 @@ struct folio { > >> /* private: */ > >> }; > >> /* public: */ > >> + struct dev_pagemap *pgmap; > > > > Shouldn't that be indented by one more tab stop? > > > > And for ease of reading, perhaps it should be placed either immediately > > before or after 'struct list_head lru;'? > > > >> +++ b/include/linux/mmzone.h > >> @@ -1134,6 +1134,12 @@ static inline bool is_zone_device_page(const struct page *page) > >> return page_zonenum(page) == ZONE_DEVICE; > >> } > >> > >> +static inline struct dev_pagemap *page_dev_pagemap(const struct page *page) > >> +{ > >> + WARN_ON(!is_zone_device_page(page)); > >> + return page_folio(page)->pgmap; > >> +} > > > > I haven't read to the end yet, but presumably we'll eventually want: > > > > static inline struct dev_pagemap *folio_dev_pagemap(const struct folio *folio) > > { > > WARN_ON(!folio_is_zone_device(folio)) > > return folio->pgmap; > > } > > > > and since we'll want it eventually, maybe now is the time to add it, > > and make page_dev_pagemap() simply call it? > > Sounds reasonable. I had open-coded folio->pgmap where it's needed > because at those points it's "obviously" a ZONE_DEVICE folio. Will add > it. Oh, if it's obvious then just do the dereference.
Hi Alistair,
kernel test robot noticed the following build errors:
[auto build test ERROR on 6f1833b8208c3b9e59eff10792667b6639365146]
url: https://github.com/intel-lab-lkp/linux/commits/Alistair-Popple/mm-gup-c-Remove-redundant-check-for-PCI-P2PDMA-page/20240910-121806
base: 6f1833b8208c3b9e59eff10792667b6639365146
patch link: https://lore.kernel.org/r/c7026449473790e2844bb82012216c57047c7639.1725941415.git-series.apopple%40nvidia.com
patch subject: [PATCH 04/12] mm: Allow compound zone device pages
config: um-allnoconfig (https://download.01.org/0day-ci/archive/20240912/202409122055.AMlMSljd-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240912/202409122055.AMlMSljd-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409122055.AMlMSljd-lkp@intel.com/
All errors (new ones prefixed by >>):
| ^
In file included from mm/memory.c:44:
In file included from include/linux/mm.h:1106:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:163:1: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
163 | _SIG_SET_BINOP(sigandnsets, _sig_andn)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:141:3: note: expanded from macro '_SIG_SET_BINOP'
141 | r->sig[2] = op(a2, b2); \
| ^ ~
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from mm/memory.c:44:
In file included from include/linux/mm.h:1106:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:174:27: note: expanded from macro '_SIG_SET_OP'
174 | case 4: set->sig[3] = op(set->sig[3]); \
| ^ ~
include/linux/signal.h:186:24: note: expanded from macro '_sig_not'
186 | #define _sig_not(x) (~(x))
| ^
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from mm/memory.c:44:
In file included from include/linux/mm.h:1106:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 3 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:174:10: note: expanded from macro '_SIG_SET_OP'
174 | case 4: set->sig[3] = op(set->sig[3]); \
| ^ ~
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from mm/memory.c:44:
In file included from include/linux/mm.h:1106:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:175:20: note: expanded from macro '_SIG_SET_OP'
175 | set->sig[2] = op(set->sig[2]); \
| ^ ~
include/linux/signal.h:186:24: note: expanded from macro '_sig_not'
186 | #define _sig_not(x) (~(x))
| ^
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from mm/memory.c:44:
In file included from include/linux/mm.h:1106:
In file included from include/linux/huge_mm.h:8:
In file included from include/linux/fs.h:33:
In file included from include/linux/percpu-rwsem.h:7:
In file included from include/linux/rcuwait.h:6:
In file included from include/linux/sched/signal.h:6:
include/linux/signal.h:187:1: warning: array index 2 is past the end of the array (that has type 'unsigned long[2]') [-Warray-bounds]
187 | _SIG_SET_OP(signotset, _sig_not)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/signal.h:175:3: note: expanded from macro '_SIG_SET_OP'
175 | set->sig[2] = op(set->sig[2]); \
| ^ ~
arch/x86/include/asm/signal.h:24:2: note: array 'sig' declared here
24 | unsigned long sig[_NSIG_WORDS];
| ^
In file included from mm/memory.c:51:
include/linux/mman.h:158:9: warning: division by zero is undefined [-Wdivision-by-zero]
158 | _calc_vm_trans(flags, MAP_SYNC, VM_SYNC ) |
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/mman.h:136:21: note: expanded from macro '_calc_vm_trans'
136 | : ((x) & (bit1)) / ((bit1) / (bit2))))
| ^ ~~~~~~~~~~~~~~~~~
include/linux/mman.h:159:9: warning: division by zero is undefined [-Wdivision-by-zero]
159 | _calc_vm_trans(flags, MAP_STACK, VM_NOHUGEPAGE) |
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/mman.h:136:21: note: expanded from macro '_calc_vm_trans'
136 | : ((x) & (bit1)) / ((bit1) / (bit2))))
| ^ ~~~~~~~~~~~~~~~~~
>> mm/memory.c:4052:12: error: call to undeclared function 'page_dev_pagemap'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
4052 | pgmap = page_dev_pagemap(vmf->page);
| ^
>> mm/memory.c:4052:10: error: incompatible integer to pointer conversion assigning to 'struct dev_pagemap *' from 'int' [-Wint-conversion]
4052 | pgmap = page_dev_pagemap(vmf->page);
| ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
42 warnings and 8 errors generated.
vim +/page_dev_pagemap +4052 mm/memory.c
3988
3989 /*
3990 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3991 * but allow concurrent faults), and pte mapped but not yet locked.
3992 * We return with pte unmapped and unlocked.
3993 *
3994 * We return with the mmap_lock locked or unlocked in the same cases
3995 * as does filemap_fault().
3996 */
3997 vm_fault_t do_swap_page(struct vm_fault *vmf)
3998 {
3999 struct vm_area_struct *vma = vmf->vma;
4000 struct folio *swapcache, *folio = NULL;
4001 struct page *page;
4002 struct swap_info_struct *si = NULL;
4003 rmap_t rmap_flags = RMAP_NONE;
4004 bool need_clear_cache = false;
4005 bool exclusive = false;
4006 swp_entry_t entry;
4007 pte_t pte;
4008 vm_fault_t ret = 0;
4009 void *shadow = NULL;
4010 int nr_pages;
4011 unsigned long page_idx;
4012 unsigned long address;
4013 pte_t *ptep;
4014
4015 if (!pte_unmap_same(vmf))
4016 goto out;
4017
4018 entry = pte_to_swp_entry(vmf->orig_pte);
4019 if (unlikely(non_swap_entry(entry))) {
4020 if (is_migration_entry(entry)) {
4021 migration_entry_wait(vma->vm_mm, vmf->pmd,
4022 vmf->address);
4023 } else if (is_device_exclusive_entry(entry)) {
4024 vmf->page = pfn_swap_entry_to_page(entry);
4025 ret = remove_device_exclusive_entry(vmf);
4026 } else if (is_device_private_entry(entry)) {
4027 struct dev_pagemap *pgmap;
4028 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
4029 /*
4030 * migrate_to_ram is not yet ready to operate
4031 * under VMA lock.
4032 */
4033 vma_end_read(vma);
4034 ret = VM_FAULT_RETRY;
4035 goto out;
4036 }
4037
4038 vmf->page = pfn_swap_entry_to_page(entry);
4039 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4040 vmf->address, &vmf->ptl);
4041 if (unlikely(!vmf->pte ||
4042 !pte_same(ptep_get(vmf->pte),
4043 vmf->orig_pte)))
4044 goto unlock;
4045
4046 /*
4047 * Get a page reference while we know the page can't be
4048 * freed.
4049 */
4050 get_page(vmf->page);
4051 pte_unmap_unlock(vmf->pte, vmf->ptl);
> 4052 pgmap = page_dev_pagemap(vmf->page);
4053 ret = pgmap->ops->migrate_to_ram(vmf);
4054 put_page(vmf->page);
4055 } else if (is_hwpoison_entry(entry)) {
4056 ret = VM_FAULT_HWPOISON;
4057 } else if (is_pte_marker_entry(entry)) {
4058 ret = handle_pte_marker(vmf);
4059 } else {
4060 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
4061 ret = VM_FAULT_SIGBUS;
4062 }
4063 goto out;
4064 }
4065
4066 /* Prevent swapoff from happening to us. */
4067 si = get_swap_device(entry);
4068 if (unlikely(!si))
4069 goto out;
4070
4071 folio = swap_cache_get_folio(entry, vma, vmf->address);
4072 if (folio)
4073 page = folio_file_page(folio, swp_offset(entry));
4074 swapcache = folio;
4075
4076 if (!folio) {
4077 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
4078 __swap_count(entry) == 1) {
4079 /*
4080 * Prevent parallel swapin from proceeding with
4081 * the cache flag. Otherwise, another thread may
4082 * finish swapin first, free the entry, and swapout
4083 * reusing the same entry. It's undetectable as
4084 * pte_same() returns true due to entry reuse.
4085 */
4086 if (swapcache_prepare(entry, 1)) {
4087 /* Relax a bit to prevent rapid repeated page faults */
4088 schedule_timeout_uninterruptible(1);
4089 goto out;
4090 }
4091 need_clear_cache = true;
4092
4093 /* skip swapcache */
4094 folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
4095 vma, vmf->address, false);
4096 if (folio) {
4097 __folio_set_locked(folio);
4098 __folio_set_swapbacked(folio);
4099
4100 if (mem_cgroup_swapin_charge_folio(folio,
4101 vma->vm_mm, GFP_KERNEL,
4102 entry)) {
4103 ret = VM_FAULT_OOM;
4104 goto out_page;
4105 }
4106 mem_cgroup_swapin_uncharge_swap(entry);
4107
4108 shadow = get_shadow_from_swap_cache(entry);
4109 if (shadow)
4110 workingset_refault(folio, shadow);
4111
4112 folio_add_lru(folio);
4113
4114 /* To provide entry to swap_read_folio() */
4115 folio->swap = entry;
4116 swap_read_folio(folio, NULL);
4117 folio->private = NULL;
4118 }
4119 } else {
4120 folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
4121 vmf);
4122 swapcache = folio;
4123 }
4124
4125 if (!folio) {
4126 /*
4127 * Back out if somebody else faulted in this pte
4128 * while we released the pte lock.
4129 */
4130 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4131 vmf->address, &vmf->ptl);
4132 if (likely(vmf->pte &&
4133 pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4134 ret = VM_FAULT_OOM;
4135 goto unlock;
4136 }
4137
4138 /* Had to read the page from swap area: Major fault */
4139 ret = VM_FAULT_MAJOR;
4140 count_vm_event(PGMAJFAULT);
4141 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
4142 page = folio_file_page(folio, swp_offset(entry));
4143 } else if (PageHWPoison(page)) {
4144 /*
4145 * hwpoisoned dirty swapcache pages are kept for killing
4146 * owner processes (which may be unknown at hwpoison time)
4147 */
4148 ret = VM_FAULT_HWPOISON;
4149 goto out_release;
4150 }
4151
4152 ret |= folio_lock_or_retry(folio, vmf);
4153 if (ret & VM_FAULT_RETRY)
4154 goto out_release;
4155
4156 if (swapcache) {
4157 /*
4158 * Make sure folio_free_swap() or swapoff did not release the
4159 * swapcache from under us. The page pin, and pte_same test
4160 * below, are not enough to exclude that. Even if it is still
4161 * swapcache, we need to check that the page's swap has not
4162 * changed.
4163 */
4164 if (unlikely(!folio_test_swapcache(folio) ||
4165 page_swap_entry(page).val != entry.val))
4166 goto out_page;
4167
4168 /*
4169 * KSM sometimes has to copy on read faults, for example, if
4170 * page->index of !PageKSM() pages would be nonlinear inside the
4171 * anon VMA -- PageKSM() is lost on actual swapout.
4172 */
4173 folio = ksm_might_need_to_copy(folio, vma, vmf->address);
4174 if (unlikely(!folio)) {
4175 ret = VM_FAULT_OOM;
4176 folio = swapcache;
4177 goto out_page;
4178 } else if (unlikely(folio == ERR_PTR(-EHWPOISON))) {
4179 ret = VM_FAULT_HWPOISON;
4180 folio = swapcache;
4181 goto out_page;
4182 }
4183 if (folio != swapcache)
4184 page = folio_page(folio, 0);
4185
4186 /*
4187 * If we want to map a page that's in the swapcache writable, we
4188 * have to detect via the refcount if we're really the exclusive
4189 * owner. Try removing the extra reference from the local LRU
4190 * caches if required.
4191 */
4192 if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
4193 !folio_test_ksm(folio) && !folio_test_lru(folio))
4194 lru_add_drain();
4195 }
4196
4197 folio_throttle_swaprate(folio, GFP_KERNEL);
4198
4199 /*
4200 * Back out if somebody else already faulted in this pte.
4201 */
4202 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
4203 &vmf->ptl);
4204 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4205 goto out_nomap;
4206
4207 if (unlikely(!folio_test_uptodate(folio))) {
4208 ret = VM_FAULT_SIGBUS;
4209 goto out_nomap;
4210 }
4211
4212 nr_pages = 1;
4213 page_idx = 0;
4214 address = vmf->address;
4215 ptep = vmf->pte;
4216 if (folio_test_large(folio) && folio_test_swapcache(folio)) {
4217 int nr = folio_nr_pages(folio);
4218 unsigned long idx = folio_page_idx(folio, page);
4219 unsigned long folio_start = address - idx * PAGE_SIZE;
4220 unsigned long folio_end = folio_start + nr * PAGE_SIZE;
4221 pte_t *folio_ptep;
4222 pte_t folio_pte;
4223
4224 if (unlikely(folio_start < max(address & PMD_MASK, vma->vm_start)))
4225 goto check_folio;
4226 if (unlikely(folio_end > pmd_addr_end(address, vma->vm_end)))
4227 goto check_folio;
4228
4229 folio_ptep = vmf->pte - idx;
4230 folio_pte = ptep_get(folio_ptep);
4231 if (!pte_same(folio_pte, pte_move_swp_offset(vmf->orig_pte, -idx)) ||
4232 swap_pte_batch(folio_ptep, nr, folio_pte) != nr)
4233 goto check_folio;
4234
4235 page_idx = idx;
4236 address = folio_start;
4237 ptep = folio_ptep;
4238 nr_pages = nr;
4239 entry = folio->swap;
4240 page = &folio->page;
4241 }
4242
4243 check_folio:
4244 /*
4245 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
4246 * must never point at an anonymous page in the swapcache that is
4247 * PG_anon_exclusive. Sanity check that this holds and especially, that
4248 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
4249 * check after taking the PT lock and making sure that nobody
4250 * concurrently faulted in this page and set PG_anon_exclusive.
4251 */
4252 BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
4253 BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
4254
4255 /*
4256 * Check under PT lock (to protect against concurrent fork() sharing
4257 * the swap entry concurrently) for certainly exclusive pages.
4258 */
4259 if (!folio_test_ksm(folio)) {
4260 exclusive = pte_swp_exclusive(vmf->orig_pte);
4261 if (folio != swapcache) {
4262 /*
4263 * We have a fresh page that is not exposed to the
4264 * swapcache -> certainly exclusive.
4265 */
4266 exclusive = true;
4267 } else if (exclusive && folio_test_writeback(folio) &&
4268 data_race(si->flags & SWP_STABLE_WRITES)) {
4269 /*
4270 * This is tricky: not all swap backends support
4271 * concurrent page modifications while under writeback.
4272 *
4273 * So if we stumble over such a page in the swapcache
4274 * we must not set the page exclusive, otherwise we can
4275 * map it writable without further checks and modify it
4276 * while still under writeback.
4277 *
4278 * For these problematic swap backends, simply drop the
4279 * exclusive marker: this is perfectly fine as we start
4280 * writeback only if we fully unmapped the page and
4281 * there are no unexpected references on the page after
4282 * unmapping succeeded. After fully unmapped, no
4283 * further GUP references (FOLL_GET and FOLL_PIN) can
4284 * appear, so dropping the exclusive marker and mapping
4285 * it only R/O is fine.
4286 */
4287 exclusive = false;
4288 }
4289 }
4290
4291 /*
4292 * Some architectures may have to restore extra metadata to the page
4293 * when reading from swap. This metadata may be indexed by swap entry
4294 * so this must be called before swap_free().
4295 */
4296 arch_swap_restore(folio_swap(entry, folio), folio);
4297
4298 /*
4299 * Remove the swap entry and conditionally try to free up the swapcache.
4300 * We're already holding a reference on the page but haven't mapped it
4301 * yet.
4302 */
4303 swap_free_nr(entry, nr_pages);
4304 if (should_try_to_free_swap(folio, vma, vmf->flags))
4305 folio_free_swap(folio);
4306
4307 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
4308 add_mm_counter(vma->vm_mm, MM_SWAPENTS, -nr_pages);
4309 pte = mk_pte(page, vma->vm_page_prot);
4310 if (pte_swp_soft_dirty(vmf->orig_pte))
4311 pte = pte_mksoft_dirty(pte);
4312 if (pte_swp_uffd_wp(vmf->orig_pte))
4313 pte = pte_mkuffd_wp(pte);
4314
4315 /*
4316 * Same logic as in do_wp_page(); however, optimize for pages that are
4317 * certainly not shared either because we just allocated them without
4318 * exposing them to the swapcache or because the swap entry indicates
4319 * exclusivity.
4320 */
4321 if (!folio_test_ksm(folio) &&
4322 (exclusive || folio_ref_count(folio) == 1)) {
4323 if ((vma->vm_flags & VM_WRITE) && !userfaultfd_pte_wp(vma, pte) &&
4324 !pte_needs_soft_dirty_wp(vma, pte)) {
4325 pte = pte_mkwrite(pte, vma);
4326 if (vmf->flags & FAULT_FLAG_WRITE) {
4327 pte = pte_mkdirty(pte);
4328 vmf->flags &= ~FAULT_FLAG_WRITE;
4329 }
4330 }
4331 rmap_flags |= RMAP_EXCLUSIVE;
4332 }
4333 folio_ref_add(folio, nr_pages - 1);
4334 flush_icache_pages(vma, page, nr_pages);
4335 vmf->orig_pte = pte_advance_pfn(pte, page_idx);
4336
4337 /* ksm created a completely new copy */
4338 if (unlikely(folio != swapcache && swapcache)) {
4339 folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
4340 folio_add_lru_vma(folio, vma);
4341 } else if (!folio_test_anon(folio)) {
4342 /*
4343 * We currently only expect small !anon folios, which are either
4344 * fully exclusive or fully shared. If we ever get large folios
4345 * here, we have to be careful.
4346 */
4347 VM_WARN_ON_ONCE(folio_test_large(folio));
4348 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
4349 folio_add_new_anon_rmap(folio, vma, address, rmap_flags);
4350 } else {
4351 folio_add_anon_rmap_ptes(folio, page, nr_pages, vma, address,
4352 rmap_flags);
4353 }
4354
4355 VM_BUG_ON(!folio_test_anon(folio) ||
4356 (pte_write(pte) && !PageAnonExclusive(page)));
4357 set_ptes(vma->vm_mm, address, ptep, pte, nr_pages);
4358 arch_do_swap_page_nr(vma->vm_mm, vma, address,
4359 pte, pte, nr_pages);
4360
4361 folio_unlock(folio);
4362 if (folio != swapcache && swapcache) {
4363 /*
4364 * Hold the lock to avoid the swap entry to be reused
4365 * until we take the PT lock for the pte_same() check
4366 * (to avoid false positives from pte_same). For
4367 * further safety release the lock after the swap_free
4368 * so that the swap count won't change under a
4369 * parallel locked swapcache.
4370 */
4371 folio_unlock(swapcache);
4372 folio_put(swapcache);
4373 }
4374
4375 if (vmf->flags & FAULT_FLAG_WRITE) {
4376 ret |= do_wp_page(vmf);
4377 if (ret & VM_FAULT_ERROR)
4378 ret &= VM_FAULT_ERROR;
4379 goto out;
4380 }
4381
4382 /* No need to invalidate - it was non-present before */
4383 update_mmu_cache_range(vmf, vma, address, ptep, nr_pages);
4384 unlock:
4385 if (vmf->pte)
4386 pte_unmap_unlock(vmf->pte, vmf->ptl);
4387 out:
4388 /* Clear the swap cache pin for direct swapin after PTL unlock */
4389 if (need_clear_cache)
4390 swapcache_clear(si, entry, 1);
4391 if (si)
4392 put_swap_device(si);
4393 return ret;
4394 out_nomap:
4395 if (vmf->pte)
4396 pte_unmap_unlock(vmf->pte, vmf->ptl);
4397 out_page:
4398 folio_unlock(folio);
4399 out_release:
4400 folio_put(folio);
4401 if (folio != swapcache && swapcache) {
4402 folio_unlock(swapcache);
4403 folio_put(swapcache);
4404 }
4405 if (need_clear_cache)
4406 swapcache_clear(si, entry, 1);
4407 if (si)
4408 put_swap_device(si);
4409 return ret;
4410 }
4411
Hi Alistair,
kernel test robot noticed the following build errors:
[auto build test ERROR on 6f1833b8208c3b9e59eff10792667b6639365146]
url: https://github.com/intel-lab-lkp/linux/commits/Alistair-Popple/mm-gup-c-Remove-redundant-check-for-PCI-P2PDMA-page/20240910-121806
base: 6f1833b8208c3b9e59eff10792667b6639365146
patch link: https://lore.kernel.org/r/c7026449473790e2844bb82012216c57047c7639.1725941415.git-series.apopple%40nvidia.com
patch subject: [PATCH 04/12] mm: Allow compound zone device pages
config: csky-defconfig (https://download.01.org/0day-ci/archive/20240912/202409122024.PPIwP6vb-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240912/202409122024.PPIwP6vb-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409122024.PPIwP6vb-lkp@intel.com/
All error/warnings (new ones prefixed by >>):
In file included from include/linux/mm.h:32,
from mm/gup.c:7:
include/linux/memremap.h: In function 'is_device_private_page':
include/linux/memremap.h:164:17: error: implicit declaration of function 'page_dev_pagemap' [-Wimplicit-function-declaration]
164 | page_dev_pagemap(page)->type == MEMORY_DEVICE_PRIVATE;
| ^~~~~~~~~~~~~~~~
include/linux/memremap.h:164:39: error: invalid type argument of '->' (have 'int')
164 | page_dev_pagemap(page)->type == MEMORY_DEVICE_PRIVATE;
| ^~
include/linux/memremap.h: In function 'is_pci_p2pdma_page':
include/linux/memremap.h:176:39: error: invalid type argument of '->' (have 'int')
176 | page_dev_pagemap(page)->type == MEMORY_DEVICE_PCI_P2PDMA;
| ^~
include/linux/memremap.h: In function 'is_device_coherent_page':
include/linux/memremap.h:182:39: error: invalid type argument of '->' (have 'int')
182 | page_dev_pagemap(page)->type == MEMORY_DEVICE_COHERENT;
| ^~
include/linux/memremap.h: In function 'is_pci_p2pdma_page':
>> include/linux/memremap.h:177:1: warning: control reaches end of non-void function [-Wreturn-type]
177 | }
| ^
include/linux/memremap.h: In function 'is_device_coherent_page':
include/linux/memremap.h:183:1: warning: control reaches end of non-void function [-Wreturn-type]
183 | }
| ^
--
In file included from include/linux/mm.h:32,
from mm/memory.c:44:
include/linux/memremap.h: In function 'is_device_private_page':
include/linux/memremap.h:164:17: error: implicit declaration of function 'page_dev_pagemap' [-Wimplicit-function-declaration]
164 | page_dev_pagemap(page)->type == MEMORY_DEVICE_PRIVATE;
| ^~~~~~~~~~~~~~~~
include/linux/memremap.h:164:39: error: invalid type argument of '->' (have 'int')
164 | page_dev_pagemap(page)->type == MEMORY_DEVICE_PRIVATE;
| ^~
include/linux/memremap.h: In function 'is_pci_p2pdma_page':
include/linux/memremap.h:176:39: error: invalid type argument of '->' (have 'int')
176 | page_dev_pagemap(page)->type == MEMORY_DEVICE_PCI_P2PDMA;
| ^~
include/linux/memremap.h: In function 'is_device_coherent_page':
include/linux/memremap.h:182:39: error: invalid type argument of '->' (have 'int')
182 | page_dev_pagemap(page)->type == MEMORY_DEVICE_COHERENT;
| ^~
mm/memory.c: In function 'do_swap_page':
>> mm/memory.c:4052:31: error: assignment to 'struct dev_pagemap *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
4052 | pgmap = page_dev_pagemap(vmf->page);
| ^
include/linux/memremap.h: In function 'is_device_private_page':
include/linux/memremap.h:165:1: warning: control reaches end of non-void function [-Wreturn-type]
165 | }
| ^
vim +4052 mm/memory.c
3988
3989 /*
3990 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3991 * but allow concurrent faults), and pte mapped but not yet locked.
3992 * We return with pte unmapped and unlocked.
3993 *
3994 * We return with the mmap_lock locked or unlocked in the same cases
3995 * as does filemap_fault().
3996 */
3997 vm_fault_t do_swap_page(struct vm_fault *vmf)
3998 {
3999 struct vm_area_struct *vma = vmf->vma;
4000 struct folio *swapcache, *folio = NULL;
4001 struct page *page;
4002 struct swap_info_struct *si = NULL;
4003 rmap_t rmap_flags = RMAP_NONE;
4004 bool need_clear_cache = false;
4005 bool exclusive = false;
4006 swp_entry_t entry;
4007 pte_t pte;
4008 vm_fault_t ret = 0;
4009 void *shadow = NULL;
4010 int nr_pages;
4011 unsigned long page_idx;
4012 unsigned long address;
4013 pte_t *ptep;
4014
4015 if (!pte_unmap_same(vmf))
4016 goto out;
4017
4018 entry = pte_to_swp_entry(vmf->orig_pte);
4019 if (unlikely(non_swap_entry(entry))) {
4020 if (is_migration_entry(entry)) {
4021 migration_entry_wait(vma->vm_mm, vmf->pmd,
4022 vmf->address);
4023 } else if (is_device_exclusive_entry(entry)) {
4024 vmf->page = pfn_swap_entry_to_page(entry);
4025 ret = remove_device_exclusive_entry(vmf);
4026 } else if (is_device_private_entry(entry)) {
4027 struct dev_pagemap *pgmap;
4028 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
4029 /*
4030 * migrate_to_ram is not yet ready to operate
4031 * under VMA lock.
4032 */
4033 vma_end_read(vma);
4034 ret = VM_FAULT_RETRY;
4035 goto out;
4036 }
4037
4038 vmf->page = pfn_swap_entry_to_page(entry);
4039 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4040 vmf->address, &vmf->ptl);
4041 if (unlikely(!vmf->pte ||
4042 !pte_same(ptep_get(vmf->pte),
4043 vmf->orig_pte)))
4044 goto unlock;
4045
4046 /*
4047 * Get a page reference while we know the page can't be
4048 * freed.
4049 */
4050 get_page(vmf->page);
4051 pte_unmap_unlock(vmf->pte, vmf->ptl);
> 4052 pgmap = page_dev_pagemap(vmf->page);
4053 ret = pgmap->ops->migrate_to_ram(vmf);
4054 put_page(vmf->page);
4055 } else if (is_hwpoison_entry(entry)) {
4056 ret = VM_FAULT_HWPOISON;
4057 } else if (is_pte_marker_entry(entry)) {
4058 ret = handle_pte_marker(vmf);
4059 } else {
4060 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
4061 ret = VM_FAULT_SIGBUS;
4062 }
4063 goto out;
4064 }
4065
4066 /* Prevent swapoff from happening to us. */
4067 si = get_swap_device(entry);
4068 if (unlikely(!si))
4069 goto out;
4070
4071 folio = swap_cache_get_folio(entry, vma, vmf->address);
4072 if (folio)
4073 page = folio_file_page(folio, swp_offset(entry));
4074 swapcache = folio;
4075
4076 if (!folio) {
4077 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
4078 __swap_count(entry) == 1) {
4079 /*
4080 * Prevent parallel swapin from proceeding with
4081 * the cache flag. Otherwise, another thread may
4082 * finish swapin first, free the entry, and swapout
4083 * reusing the same entry. It's undetectable as
4084 * pte_same() returns true due to entry reuse.
4085 */
4086 if (swapcache_prepare(entry, 1)) {
4087 /* Relax a bit to prevent rapid repeated page faults */
4088 schedule_timeout_uninterruptible(1);
4089 goto out;
4090 }
4091 need_clear_cache = true;
4092
4093 /* skip swapcache */
4094 folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0,
4095 vma, vmf->address, false);
4096 if (folio) {
4097 __folio_set_locked(folio);
4098 __folio_set_swapbacked(folio);
4099
4100 if (mem_cgroup_swapin_charge_folio(folio,
4101 vma->vm_mm, GFP_KERNEL,
4102 entry)) {
4103 ret = VM_FAULT_OOM;
4104 goto out_page;
4105 }
4106 mem_cgroup_swapin_uncharge_swap(entry);
4107
4108 shadow = get_shadow_from_swap_cache(entry);
4109 if (shadow)
4110 workingset_refault(folio, shadow);
4111
4112 folio_add_lru(folio);
4113
4114 /* To provide entry to swap_read_folio() */
4115 folio->swap = entry;
4116 swap_read_folio(folio, NULL);
4117 folio->private = NULL;
4118 }
4119 } else {
4120 folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
4121 vmf);
4122 swapcache = folio;
4123 }
4124
4125 if (!folio) {
4126 /*
4127 * Back out if somebody else faulted in this pte
4128 * while we released the pte lock.
4129 */
4130 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4131 vmf->address, &vmf->ptl);
4132 if (likely(vmf->pte &&
4133 pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4134 ret = VM_FAULT_OOM;
4135 goto unlock;
4136 }
4137
4138 /* Had to read the page from swap area: Major fault */
4139 ret = VM_FAULT_MAJOR;
4140 count_vm_event(PGMAJFAULT);
4141 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
4142 page = folio_file_page(folio, swp_offset(entry));
4143 } else if (PageHWPoison(page)) {
4144 /*
4145 * hwpoisoned dirty swapcache pages are kept for killing
4146 * owner processes (which may be unknown at hwpoison time)
4147 */
4148 ret = VM_FAULT_HWPOISON;
4149 goto out_release;
4150 }
4151
4152 ret |= folio_lock_or_retry(folio, vmf);
4153 if (ret & VM_FAULT_RETRY)
4154 goto out_release;
4155
4156 if (swapcache) {
4157 /*
4158 * Make sure folio_free_swap() or swapoff did not release the
4159 * swapcache from under us. The page pin, and pte_same test
4160 * below, are not enough to exclude that. Even if it is still
4161 * swapcache, we need to check that the page's swap has not
4162 * changed.
4163 */
4164 if (unlikely(!folio_test_swapcache(folio) ||
4165 page_swap_entry(page).val != entry.val))
4166 goto out_page;
4167
4168 /*
4169 * KSM sometimes has to copy on read faults, for example, if
4170 * page->index of !PageKSM() pages would be nonlinear inside the
4171 * anon VMA -- PageKSM() is lost on actual swapout.
4172 */
4173 folio = ksm_might_need_to_copy(folio, vma, vmf->address);
4174 if (unlikely(!folio)) {
4175 ret = VM_FAULT_OOM;
4176 folio = swapcache;
4177 goto out_page;
4178 } else if (unlikely(folio == ERR_PTR(-EHWPOISON))) {
4179 ret = VM_FAULT_HWPOISON;
4180 folio = swapcache;
4181 goto out_page;
4182 }
4183 if (folio != swapcache)
4184 page = folio_page(folio, 0);
4185
4186 /*
4187 * If we want to map a page that's in the swapcache writable, we
4188 * have to detect via the refcount if we're really the exclusive
4189 * owner. Try removing the extra reference from the local LRU
4190 * caches if required.
4191 */
4192 if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
4193 !folio_test_ksm(folio) && !folio_test_lru(folio))
4194 lru_add_drain();
4195 }
4196
4197 folio_throttle_swaprate(folio, GFP_KERNEL);
4198
4199 /*
4200 * Back out if somebody else already faulted in this pte.
4201 */
4202 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
4203 &vmf->ptl);
4204 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4205 goto out_nomap;
4206
4207 if (unlikely(!folio_test_uptodate(folio))) {
4208 ret = VM_FAULT_SIGBUS;
4209 goto out_nomap;
4210 }
4211
4212 nr_pages = 1;
4213 page_idx = 0;
4214 address = vmf->address;
4215 ptep = vmf->pte;
4216 if (folio_test_large(folio) && folio_test_swapcache(folio)) {
4217 int nr = folio_nr_pages(folio);
4218 unsigned long idx = folio_page_idx(folio, page);
4219 unsigned long folio_start = address - idx * PAGE_SIZE;
4220 unsigned long folio_end = folio_start + nr * PAGE_SIZE;
4221 pte_t *folio_ptep;
4222 pte_t folio_pte;
4223
4224 if (unlikely(folio_start < max(address & PMD_MASK, vma->vm_start)))
4225 goto check_folio;
4226 if (unlikely(folio_end > pmd_addr_end(address, vma->vm_end)))
4227 goto check_folio;
4228
4229 folio_ptep = vmf->pte - idx;
4230 folio_pte = ptep_get(folio_ptep);
4231 if (!pte_same(folio_pte, pte_move_swp_offset(vmf->orig_pte, -idx)) ||
4232 swap_pte_batch(folio_ptep, nr, folio_pte) != nr)
4233 goto check_folio;
4234
4235 page_idx = idx;
4236 address = folio_start;
4237 ptep = folio_ptep;
4238 nr_pages = nr;
4239 entry = folio->swap;
4240 page = &folio->page;
4241 }
4242
4243 check_folio:
4244 /*
4245 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
4246 * must never point at an anonymous page in the swapcache that is
4247 * PG_anon_exclusive. Sanity check that this holds and especially, that
4248 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
4249 * check after taking the PT lock and making sure that nobody
4250 * concurrently faulted in this page and set PG_anon_exclusive.
4251 */
4252 BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
4253 BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
4254
4255 /*
4256 * Check under PT lock (to protect against concurrent fork() sharing
4257 * the swap entry concurrently) for certainly exclusive pages.
4258 */
4259 if (!folio_test_ksm(folio)) {
4260 exclusive = pte_swp_exclusive(vmf->orig_pte);
4261 if (folio != swapcache) {
4262 /*
4263 * We have a fresh page that is not exposed to the
4264 * swapcache -> certainly exclusive.
4265 */
4266 exclusive = true;
4267 } else if (exclusive && folio_test_writeback(folio) &&
4268 data_race(si->flags & SWP_STABLE_WRITES)) {
4269 /*
4270 * This is tricky: not all swap backends support
4271 * concurrent page modifications while under writeback.
4272 *
4273 * So if we stumble over such a page in the swapcache
4274 * we must not set the page exclusive, otherwise we can
4275 * map it writable without further checks and modify it
4276 * while still under writeback.
4277 *
4278 * For these problematic swap backends, simply drop the
4279 * exclusive marker: this is perfectly fine as we start
4280 * writeback only if we fully unmapped the page and
4281 * there are no unexpected references on the page after
4282 * unmapping succeeded. After fully unmapped, no
4283 * further GUP references (FOLL_GET and FOLL_PIN) can
4284 * appear, so dropping the exclusive marker and mapping
4285 * it only R/O is fine.
4286 */
4287 exclusive = false;
4288 }
4289 }
4290
4291 /*
4292 * Some architectures may have to restore extra metadata to the page
4293 * when reading from swap. This metadata may be indexed by swap entry
4294 * so this must be called before swap_free().
4295 */
4296 arch_swap_restore(folio_swap(entry, folio), folio);
4297
4298 /*
4299 * Remove the swap entry and conditionally try to free up the swapcache.
4300 * We're already holding a reference on the page but haven't mapped it
4301 * yet.
4302 */
4303 swap_free_nr(entry, nr_pages);
4304 if (should_try_to_free_swap(folio, vma, vmf->flags))
4305 folio_free_swap(folio);
4306
4307 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
4308 add_mm_counter(vma->vm_mm, MM_SWAPENTS, -nr_pages);
4309 pte = mk_pte(page, vma->vm_page_prot);
4310 if (pte_swp_soft_dirty(vmf->orig_pte))
4311 pte = pte_mksoft_dirty(pte);
4312 if (pte_swp_uffd_wp(vmf->orig_pte))
4313 pte = pte_mkuffd_wp(pte);
4314
4315 /*
4316 * Same logic as in do_wp_page(); however, optimize for pages that are
4317 * certainly not shared either because we just allocated them without
4318 * exposing them to the swapcache or because the swap entry indicates
4319 * exclusivity.
4320 */
4321 if (!folio_test_ksm(folio) &&
4322 (exclusive || folio_ref_count(folio) == 1)) {
4323 if ((vma->vm_flags & VM_WRITE) && !userfaultfd_pte_wp(vma, pte) &&
4324 !pte_needs_soft_dirty_wp(vma, pte)) {
4325 pte = pte_mkwrite(pte, vma);
4326 if (vmf->flags & FAULT_FLAG_WRITE) {
4327 pte = pte_mkdirty(pte);
4328 vmf->flags &= ~FAULT_FLAG_WRITE;
4329 }
4330 }
4331 rmap_flags |= RMAP_EXCLUSIVE;
4332 }
4333 folio_ref_add(folio, nr_pages - 1);
4334 flush_icache_pages(vma, page, nr_pages);
4335 vmf->orig_pte = pte_advance_pfn(pte, page_idx);
4336
4337 /* ksm created a completely new copy */
4338 if (unlikely(folio != swapcache && swapcache)) {
4339 folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
4340 folio_add_lru_vma(folio, vma);
4341 } else if (!folio_test_anon(folio)) {
4342 /*
4343 * We currently only expect small !anon folios, which are either
4344 * fully exclusive or fully shared. If we ever get large folios
4345 * here, we have to be careful.
4346 */
4347 VM_WARN_ON_ONCE(folio_test_large(folio));
4348 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
4349 folio_add_new_anon_rmap(folio, vma, address, rmap_flags);
4350 } else {
4351 folio_add_anon_rmap_ptes(folio, page, nr_pages, vma, address,
4352 rmap_flags);
4353 }
4354
4355 VM_BUG_ON(!folio_test_anon(folio) ||
4356 (pte_write(pte) && !PageAnonExclusive(page)));
4357 set_ptes(vma->vm_mm, address, ptep, pte, nr_pages);
4358 arch_do_swap_page_nr(vma->vm_mm, vma, address,
4359 pte, pte, nr_pages);
4360
4361 folio_unlock(folio);
4362 if (folio != swapcache && swapcache) {
4363 /*
4364 * Hold the lock to avoid the swap entry to be reused
4365 * until we take the PT lock for the pte_same() check
4366 * (to avoid false positives from pte_same). For
4367 * further safety release the lock after the swap_free
4368 * so that the swap count won't change under a
4369 * parallel locked swapcache.
4370 */
4371 folio_unlock(swapcache);
4372 folio_put(swapcache);
4373 }
4374
4375 if (vmf->flags & FAULT_FLAG_WRITE) {
4376 ret |= do_wp_page(vmf);
4377 if (ret & VM_FAULT_ERROR)
4378 ret &= VM_FAULT_ERROR;
4379 goto out;
4380 }
4381
4382 /* No need to invalidate - it was non-present before */
4383 update_mmu_cache_range(vmf, vma, address, ptep, nr_pages);
4384 unlock:
4385 if (vmf->pte)
4386 pte_unmap_unlock(vmf->pte, vmf->ptl);
4387 out:
4388 /* Clear the swap cache pin for direct swapin after PTL unlock */
4389 if (need_clear_cache)
4390 swapcache_clear(si, entry, 1);
4391 if (si)
4392 put_swap_device(si);
4393 return ret;
4394 out_nomap:
4395 if (vmf->pte)
4396 pte_unmap_unlock(vmf->pte, vmf->ptl);
4397 out_page:
4398 folio_unlock(folio);
4399 out_release:
4400 folio_put(folio);
4401 if (folio != swapcache && swapcache) {
4402 folio_unlock(swapcache);
4403 folio_put(swapcache);
4404 }
4405 if (need_clear_cache)
4406 swapcache_clear(si, entry, 1);
4407 if (si)
4408 put_swap_device(si);
4409 return ret;
4410 }
4411
Alistair Popple wrote: > Zone device pages are used to represent various type of device memory > managed by device drivers. Currently compound zone device pages are > not supported. This is because MEMORY_DEVICE_FS_DAX pages are the only > user of higher order zone device pages and have their own page > reference counting. > > A future change will unify FS DAX reference counting with normal page > reference counting rules and remove the special FS DAX reference > counting. Supporting that requires compound zone device pages. > > Supporting compound zone device pages requires compound_head() to > distinguish between head and tail pages whilst still preserving the > special struct page fields that are specific to zone device pages. > > A tail page is distinguished by having bit zero being set in > page->compound_head, with the remaining bits pointing to the head > page. For zone device pages page->compound_head is shared with > page->pgmap. > > The page->pgmap field is common to all pages within a memory section. > Therefore pgmap is the same for both head and tail pages and can be > moved into the folio and we can use the standard scheme to find > compound_head from a tail page. > > Signed-off-by: Alistair Popple <apopple@nvidia.com> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> > > --- > > Changes since v1: > > - Move pgmap to the folio as suggested by Matthew Wilcox > --- > drivers/gpu/drm/nouveau/nouveau_dmem.c | 3 ++- > drivers/pci/p2pdma.c | 6 +++--- > include/linux/memremap.h | 6 +++--- > include/linux/migrate.h | 4 ++-- > include/linux/mm_types.h | 9 +++++++-- > include/linux/mmzone.h | 8 +++++++- > lib/test_hmm.c | 3 ++- > mm/hmm.c | 2 +- > mm/memory.c | 4 +++- > mm/memremap.c | 14 +++++++------- > mm/migrate_device.c | 7 +++++-- > mm/mm_init.c | 2 +- > 12 files changed, 43 insertions(+), 25 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c > index 6fb65b0..58d308c 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c > +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c > @@ -88,7 +88,8 @@ struct nouveau_dmem { > > static struct nouveau_dmem_chunk *nouveau_page_to_chunk(struct page *page) > { > - return container_of(page->pgmap, struct nouveau_dmem_chunk, pagemap); > + return container_of(page_dev_pagemap(page), struct nouveau_dmem_chunk, page_dev_pagemap() feels like a mouthful. I would be ok with page_pgmap() since that is the most common idenifier for struct struct dev_pagemap instances. > + pagemap); > } > > static struct nouveau_drm *page_to_drm(struct page *page) > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 210b9f4..a58f2c1 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -199,7 +199,7 @@ static const struct attribute_group p2pmem_group = { > > static void p2pdma_page_free(struct page *page) > { > - struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page->pgmap); > + struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page_dev_pagemap(page)); > /* safe to dereference while a reference is held to the percpu ref */ > struct pci_p2pdma *p2pdma = > rcu_dereference_protected(pgmap->provider->p2pdma, 1); > @@ -1022,8 +1022,8 @@ enum pci_p2pdma_map_type > pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev, > struct scatterlist *sg) > { > - if (state->pgmap != sg_page(sg)->pgmap) { > - state->pgmap = sg_page(sg)->pgmap; > + if (state->pgmap != page_dev_pagemap(sg_page(sg))) { > + state->pgmap = page_dev_pagemap(sg_page(sg)); > state->map = pci_p2pdma_map_type(state->pgmap, dev); > state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset; > } > diff --git a/include/linux/memremap.h b/include/linux/memremap.h > index 3f7143a..14273e6 100644 > --- a/include/linux/memremap.h > +++ b/include/linux/memremap.h > @@ -161,7 +161,7 @@ static inline bool is_device_private_page(const struct page *page) > { > return IS_ENABLED(CONFIG_DEVICE_PRIVATE) && > is_zone_device_page(page) && > - page->pgmap->type == MEMORY_DEVICE_PRIVATE; > + page_dev_pagemap(page)->type == MEMORY_DEVICE_PRIVATE; > } > > static inline bool folio_is_device_private(const struct folio *folio) > @@ -173,13 +173,13 @@ static inline bool is_pci_p2pdma_page(const struct page *page) > { > return IS_ENABLED(CONFIG_PCI_P2PDMA) && > is_zone_device_page(page) && > - page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA; > + page_dev_pagemap(page)->type == MEMORY_DEVICE_PCI_P2PDMA; > } > > static inline bool is_device_coherent_page(const struct page *page) > { > return is_zone_device_page(page) && > - page->pgmap->type == MEMORY_DEVICE_COHERENT; > + page_dev_pagemap(page)->type == MEMORY_DEVICE_COHERENT; > } > > static inline bool folio_is_device_coherent(const struct folio *folio) > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index 002e49b..9a85a82 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -207,8 +207,8 @@ struct migrate_vma { > unsigned long end; > > /* > - * Set to the owner value also stored in page->pgmap->owner for > - * migrating out of device private memory. The flags also need to > + * Set to the owner value also stored in page_dev_pagemap(page)->owner > + * for migrating out of device private memory. The flags also need to > * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. > * The caller should always set this field when using mmu notifier > * callbacks to avoid device MMU invalidations for device private > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 6e3bdf8..c2f1d53 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -129,8 +129,11 @@ struct page { > unsigned long compound_head; /* Bit zero is set */ > }; > struct { /* ZONE_DEVICE pages */ > - /** @pgmap: Points to the hosting device page map. */ > - struct dev_pagemap *pgmap; > + /* > + * The first word is used for compound_head or folio > + * pgmap > + */ > + void *_unused; I would feel better with "_unused_pgmap_compound_head", similar to how _unused_slab_obj_exts in 'struct foio' indicates the placeholer contents. > void *zone_device_data; > /* > * ZONE_DEVICE private pages are counted as being > @@ -299,6 +302,7 @@ typedef struct { > * @_refcount: Do not access this member directly. Use folio_ref_count() > * to find how many references there are to this folio. > * @memcg_data: Memory Control Group data. > + * @pgmap: Metadata for ZONE_DEVICE mappings > * @virtual: Virtual address in the kernel direct map. > * @_last_cpupid: IDs of last CPU and last process that accessed the folio. > * @_entire_mapcount: Do not use directly, call folio_entire_mapcount(). > @@ -337,6 +341,7 @@ struct folio { > /* private: */ > }; > /* public: */ > + struct dev_pagemap *pgmap; > }; > struct address_space *mapping; > pgoff_t index; > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 17506e4..e191434 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -1134,6 +1134,12 @@ static inline bool is_zone_device_page(const struct page *page) > return page_zonenum(page) == ZONE_DEVICE; > } > > +static inline struct dev_pagemap *page_dev_pagemap(const struct page *page) > +{ > + WARN_ON(!is_zone_device_page(page)); VM_WARN_ON()? With the above fixups: Reviewed-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c index 6fb65b0..58d308c 100644 --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c @@ -88,7 +88,8 @@ struct nouveau_dmem { static struct nouveau_dmem_chunk *nouveau_page_to_chunk(struct page *page) { - return container_of(page->pgmap, struct nouveau_dmem_chunk, pagemap); + return container_of(page_dev_pagemap(page), struct nouveau_dmem_chunk, + pagemap); } static struct nouveau_drm *page_to_drm(struct page *page) diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 210b9f4..a58f2c1 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -199,7 +199,7 @@ static const struct attribute_group p2pmem_group = { static void p2pdma_page_free(struct page *page) { - struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page->pgmap); + struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page_dev_pagemap(page)); /* safe to dereference while a reference is held to the percpu ref */ struct pci_p2pdma *p2pdma = rcu_dereference_protected(pgmap->provider->p2pdma, 1); @@ -1022,8 +1022,8 @@ enum pci_p2pdma_map_type pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev, struct scatterlist *sg) { - if (state->pgmap != sg_page(sg)->pgmap) { - state->pgmap = sg_page(sg)->pgmap; + if (state->pgmap != page_dev_pagemap(sg_page(sg))) { + state->pgmap = page_dev_pagemap(sg_page(sg)); state->map = pci_p2pdma_map_type(state->pgmap, dev); state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset; } diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 3f7143a..14273e6 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -161,7 +161,7 @@ static inline bool is_device_private_page(const struct page *page) { return IS_ENABLED(CONFIG_DEVICE_PRIVATE) && is_zone_device_page(page) && - page->pgmap->type == MEMORY_DEVICE_PRIVATE; + page_dev_pagemap(page)->type == MEMORY_DEVICE_PRIVATE; } static inline bool folio_is_device_private(const struct folio *folio) @@ -173,13 +173,13 @@ static inline bool is_pci_p2pdma_page(const struct page *page) { return IS_ENABLED(CONFIG_PCI_P2PDMA) && is_zone_device_page(page) && - page->pgmap->type == MEMORY_DEVICE_PCI_P2PDMA; + page_dev_pagemap(page)->type == MEMORY_DEVICE_PCI_P2PDMA; } static inline bool is_device_coherent_page(const struct page *page) { return is_zone_device_page(page) && - page->pgmap->type == MEMORY_DEVICE_COHERENT; + page_dev_pagemap(page)->type == MEMORY_DEVICE_COHERENT; } static inline bool folio_is_device_coherent(const struct folio *folio) diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 002e49b..9a85a82 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -207,8 +207,8 @@ struct migrate_vma { unsigned long end; /* - * Set to the owner value also stored in page->pgmap->owner for - * migrating out of device private memory. The flags also need to + * Set to the owner value also stored in page_dev_pagemap(page)->owner + * for migrating out of device private memory. The flags also need to * be set to MIGRATE_VMA_SELECT_DEVICE_PRIVATE. * The caller should always set this field when using mmu notifier * callbacks to avoid device MMU invalidations for device private diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 6e3bdf8..c2f1d53 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -129,8 +129,11 @@ struct page { unsigned long compound_head; /* Bit zero is set */ }; struct { /* ZONE_DEVICE pages */ - /** @pgmap: Points to the hosting device page map. */ - struct dev_pagemap *pgmap; + /* + * The first word is used for compound_head or folio + * pgmap + */ + void *_unused; void *zone_device_data; /* * ZONE_DEVICE private pages are counted as being @@ -299,6 +302,7 @@ typedef struct { * @_refcount: Do not access this member directly. Use folio_ref_count() * to find how many references there are to this folio. * @memcg_data: Memory Control Group data. + * @pgmap: Metadata for ZONE_DEVICE mappings * @virtual: Virtual address in the kernel direct map. * @_last_cpupid: IDs of last CPU and last process that accessed the folio. * @_entire_mapcount: Do not use directly, call folio_entire_mapcount(). @@ -337,6 +341,7 @@ struct folio { /* private: */ }; /* public: */ + struct dev_pagemap *pgmap; }; struct address_space *mapping; pgoff_t index; diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 17506e4..e191434 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1134,6 +1134,12 @@ static inline bool is_zone_device_page(const struct page *page) return page_zonenum(page) == ZONE_DEVICE; } +static inline struct dev_pagemap *page_dev_pagemap(const struct page *page) +{ + WARN_ON(!is_zone_device_page(page)); + return page_folio(page)->pgmap; +} + /* * Consecutive zone device pages should not be merged into the same sgl * or bvec segment with other types of pages or if they belong to different @@ -1149,7 +1155,7 @@ static inline bool zone_device_pages_have_same_pgmap(const struct page *a, return false; if (!is_zone_device_page(a)) return true; - return a->pgmap == b->pgmap; + return page_dev_pagemap(a) == page_dev_pagemap(b); } extern void memmap_init_zone_device(struct zone *, unsigned long, diff --git a/lib/test_hmm.c b/lib/test_hmm.c index 056f2e4..b072ca9 100644 --- a/lib/test_hmm.c +++ b/lib/test_hmm.c @@ -195,7 +195,8 @@ static int dmirror_fops_release(struct inode *inode, struct file *filp) static struct dmirror_chunk *dmirror_page_to_chunk(struct page *page) { - return container_of(page->pgmap, struct dmirror_chunk, pagemap); + return container_of(page_dev_pagemap(page), struct dmirror_chunk, + pagemap); } static struct dmirror_device *dmirror_page_to_device(struct page *page) diff --git a/mm/hmm.c b/mm/hmm.c index 7e0229a..a11807c 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -248,7 +248,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, * just report the PFN. */ if (is_device_private_entry(entry) && - pfn_swap_entry_to_page(entry)->pgmap->owner == + page_dev_pagemap(pfn_swap_entry_to_page(entry))->owner == range->dev_private_owner) { cpu_flags = HMM_PFN_VALID; if (is_writable_device_private_entry(entry)) diff --git a/mm/memory.c b/mm/memory.c index c31ea30..d2785fb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4024,6 +4024,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) vmf->page = pfn_swap_entry_to_page(entry); ret = remove_device_exclusive_entry(vmf); } else if (is_device_private_entry(entry)) { + struct dev_pagemap *pgmap; if (vmf->flags & FAULT_FLAG_VMA_LOCK) { /* * migrate_to_ram is not yet ready to operate @@ -4048,7 +4049,8 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) */ get_page(vmf->page); pte_unmap_unlock(vmf->pte, vmf->ptl); - ret = vmf->page->pgmap->ops->migrate_to_ram(vmf); + pgmap = page_dev_pagemap(vmf->page); + ret = pgmap->ops->migrate_to_ram(vmf); put_page(vmf->page); } else if (is_hwpoison_entry(entry)) { ret = VM_FAULT_HWPOISON; diff --git a/mm/memremap.c b/mm/memremap.c index 07bbe0e..e885bc9 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -458,8 +458,8 @@ EXPORT_SYMBOL_GPL(get_dev_pagemap); void free_zone_device_folio(struct folio *folio) { - if (WARN_ON_ONCE(!folio->page.pgmap->ops || - !folio->page.pgmap->ops->page_free)) + if (WARN_ON_ONCE(!folio->pgmap->ops || + !folio->pgmap->ops->page_free)) return; mem_cgroup_uncharge(folio); @@ -486,12 +486,12 @@ void free_zone_device_folio(struct folio *folio) * to clear folio->mapping. */ folio->mapping = NULL; - folio->page.pgmap->ops->page_free(folio_page(folio, 0)); + folio->pgmap->ops->page_free(folio_page(folio, 0)); - switch (folio->page.pgmap->type) { + switch (folio->pgmap->type) { case MEMORY_DEVICE_PRIVATE: case MEMORY_DEVICE_COHERENT: - put_dev_pagemap(folio->page.pgmap); + put_dev_pagemap(folio->pgmap); break; case MEMORY_DEVICE_FS_DAX: @@ -514,7 +514,7 @@ void zone_device_page_init(struct page *page) * Drivers shouldn't be allocating pages after calling * memunmap_pages(). */ - WARN_ON_ONCE(!percpu_ref_tryget_live(&page->pgmap->ref)); + WARN_ON_ONCE(!percpu_ref_tryget_live(&page_dev_pagemap(page)->ref)); set_page_count(page, 1); lock_page(page); } @@ -523,7 +523,7 @@ EXPORT_SYMBOL_GPL(zone_device_page_init); #ifdef CONFIG_FS_DAX bool __put_devmap_managed_folio_refs(struct folio *folio, int refs) { - if (folio->page.pgmap->type != MEMORY_DEVICE_FS_DAX) + if (folio->pgmap->type != MEMORY_DEVICE_FS_DAX) return false; /* diff --git a/mm/migrate_device.c b/mm/migrate_device.c index 6d66dc1..9d30107 100644 --- a/mm/migrate_device.c +++ b/mm/migrate_device.c @@ -106,6 +106,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, arch_enter_lazy_mmu_mode(); for (; addr < end; addr += PAGE_SIZE, ptep++) { + struct dev_pagemap *pgmap; unsigned long mpfn = 0, pfn; struct folio *folio; struct page *page; @@ -133,9 +134,10 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, goto next; page = pfn_swap_entry_to_page(entry); + pgmap = page_dev_pagemap(page); if (!(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_PRIVATE) || - page->pgmap->owner != migrate->pgmap_owner) + pgmap->owner != migrate->pgmap_owner) goto next; mpfn = migrate_pfn(page_to_pfn(page)) | @@ -151,12 +153,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, goto next; } page = vm_normal_page(migrate->vma, addr, pte); + pgmap = page_dev_pagemap(page); if (page && !is_zone_device_page(page) && !(migrate->flags & MIGRATE_VMA_SELECT_SYSTEM)) goto next; else if (page && is_device_coherent_page(page) && (!(migrate->flags & MIGRATE_VMA_SELECT_DEVICE_COHERENT) || - page->pgmap->owner != migrate->pgmap_owner)) + pgmap->owner != migrate->pgmap_owner)) goto next; mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE; mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0; diff --git a/mm/mm_init.c b/mm/mm_init.c index 0489820..3d0611e 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -996,7 +996,7 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn, * and zone_device_data. It is a bug if a ZONE_DEVICE page is * ever freed or placed on a driver-private list. */ - page->pgmap = pgmap; + page_folio(page)->pgmap = pgmap; page->zone_device_data = NULL; /*