Platform with advance system bus (like CAPI or CCIX) allow device
memory to be accessible from CPU in a cache coherent fashion. Add
a new type of ZONE_DEVICE to represent such memory. The use case
are the same as for the un-addressable device memory but without
all the corners cases.
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Balbir Singh <balbirs@xxxxxxxxxxx>
Cc: Aneesh Kumar <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 2 +-
include/linux/ioport.h | 1 +
include/linux/memremap.h | 21 +++++++++++++++++
include/linux/mm.h | 16 ++++++++-----
kernel/memremap.c | 11 ++++++---
mm/Kconfig | 13 +++++++++++
mm/gup.c | 7 ++++++
mm/madvise.c | 2 +-
mm/memory.c | 46 +++++++++++++++++++++++++++++++++----
mm/migrate.c | 60 ++++++++++++++++++++++++++++++++----------------
mm/swap.c | 11 +++++++++
11 files changed, 154 insertions(+), 36 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 90b2fa4..78b1eca 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1187,7 +1187,7 @@ static pagemap_entry_t pte_to_pagemap_entry(struct pagemapread *pm,
if (pm->show_pfn)
frame = pte_pfn(pte);
flags |= PM_PRESENT;
- page = vm_normal_page(vma, addr, pte);
+ page = _vm_normal_page(vma, addr, pte, true);
if (pte_soft_dirty(pte))
flags |= PM_SOFT_DIRTY;
} else if (is_swap_pte(pte)) {
diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 3a4f691..f5cf32e 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -131,6 +131,7 @@ enum {
IORES_DESC_PERSISTENT_MEMORY = 4,
IORES_DESC_PERSISTENT_MEMORY_LEGACY = 5,
IORES_DESC_DEVICE_PRIVATE_MEMORY = 6,
+ IORES_DESC_DEVICE_PUBLIC_MEMORY = 7,
};
/* helpers to define resources */
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index d6909ea..c8506d3 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -56,10 +56,18 @@ static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
* page must be treated as an opaque object, rather than a "normal" struct page.
* A more complete discussion of unaddressable memory may be found in
* include/linux/hmm.h and Documentation/vm/hmm.txt.
+ *
+ * MEMORY_DEVICE_PUBLIC:
+ * Device memory that is cache coherent from device and CPU point of view. This
+ * is use on platform that have an advance system bus (like CAPI or CCIX). A
+ * driver can hotplug the device memory using ZONE_DEVICE and with that memory
+ * type. Any page of a process can be migrated to such memory. However no one
+ * should be allow to pin such memory so that it can always be evicted.
*/
enum memory_type {
MEMORY_DEVICE_PERSISTENT = 0,
MEMORY_DEVICE_PRIVATE,
+ MEMORY_DEVICE_PUBLIC,
};
/*
@@ -91,6 +99,8 @@ enum memory_type {
* The page_free() callback is called once the page refcount reaches 1
* (ZONE_DEVICE pages never reach 0 refcount unless there is a refcount bug.
* This allows the device driver to implement its own memory management.)
+ *
+ * For MEMORY_DEVICE_CACHE_COHERENT only the page_free() callback matter.
*/
typedef int (*dev_page_fault_t)(struct vm_area_struct *vma,
unsigned long addr,
@@ -133,6 +143,12 @@ static inline bool is_device_private_page(const struct page *page)
return is_zone_device_page(page) &&
page->pgmap->type == MEMORY_DEVICE_PRIVATE;
}
+
+static inline bool is_device_public_page(const struct page *page)
+{
+ return is_zone_device_page(page) &&
+ page->pgmap->type == MEMORY_DEVICE_PUBLIC;
+}
#else
static inline void *devm_memremap_pages(struct device *dev,
struct resource *res, struct percpu_ref *ref,
@@ -156,6 +172,11 @@ static inline bool is_device_private_page(const struct page *page)
{
return false;
}
+
+static inline bool is_device_public_page(const struct page *page)
+{
+ return false;
+}
#endif
/**
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e74a183..d267482 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -797,14 +797,15 @@ static inline bool is_zone_device_page(const struct page *page)
#endif
#ifdef CONFIG_DEVICE_PRIVATE
-void put_zone_device_private_page(struct page *page);
+void put_zone_device_private_or_public_page(struct page *page);
#else
-static inline void put_zone_device_private_page(struct page *page)
+static inline void put_zone_device_private_or_public_page(struct page *page)
{
}
#endif
static inline bool is_device_private_page(const struct page *page);
+static inline bool is_device_public_page(const struct page *page);
DECLARE_STATIC_KEY_FALSE(device_private_key);
@@ -830,8 +831,9 @@ static inline void put_page(struct page *page)
* include/linux/memremap.h and HMM for details.
*/
if (static_branch_unlikely(&device_private_key) &&
- unlikely(is_device_private_page(page))) {
- put_zone_device_private_page(page);
+ unlikely(is_device_private_page(page) ||
+ is_device_public_page(page))) {
+ put_zone_device_private_or_public_page(page);
return;
}
@@ -1220,8 +1222,10 @@ struct zap_details {
pgoff_t last_index; /* Highest page->index to unmap */
};
-struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
- pte_t pte);
+struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
+ pte_t pte, bool with_public_device);
+#define vm_normal_page(vma, addr, pte) _vm_normal_page(vma, addr, pte, false)
+
struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
pmd_t pmd);
diff --git a/kernel/memremap.c b/kernel/memremap.c
index e82456c..da74775 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -466,7 +466,7 @@ struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
#ifdef CONFIG_DEVICE_PRIVATE
-void put_zone_device_private_page(struct page *page)
+void put_zone_device_private_or_public_page(struct page *page)
{
int count = page_ref_dec_return(page);
@@ -474,10 +474,15 @@ void put_zone_device_private_page(struct page *page)
* If refcount is 1 then page is freed and refcount is stable as nobody
* holds a reference on the page.
*/
- if (count == 1)
+ if (count == 1) {
+ /* Clear Active bit in case of parallel mark_page_accessed */
+ __ClearPageActive(page);
+ __ClearPageWaiters(page);
+
page->pgmap->page_free(page, page->pgmap->data);
+ }
else if (!count)
__put_page(page);
}
-EXPORT_SYMBOL(put_zone_device_private_page);
+EXPORT_SYMBOL(put_zone_device_private_or_public_page);
#endif /* CONFIG_DEVICE_PRIVATE */
diff --git a/mm/Kconfig b/mm/Kconfig
index dd11b4d..ad082b9 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -731,6 +731,19 @@ config DEVICE_PRIVATE
memory; i.e., memory that is only accessible from the device (or
group of devices).
+config DEVICE_PUBLIC
+ bool "Unaddressable device memory (GPU memory, ...)"
+ depends on X86_64
+ depends on ZONE_DEVICE
+ depends on MEMORY_HOTPLUG
+ depends on MEMORY_HOTREMOVE
+ depends on SPARSEMEM_VMEMMAP
+
+ help
+ Allows creation of struct pages to represent addressable device
+ memory; i.e., memory that is accessible from both the device and
+ the CPU
+
config FRAME_VECTOR
bool
diff --git a/mm/gup.c b/mm/gup.c
index b73e426..d771850 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -438,6 +438,13 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(*pte)))
goto unmap;
*page = pte_page(*pte);
+
+ /*
+ * This should never happen (a device public page in the gate
+ * area).
+ */
+ if (is_device_public_page(*page))
+ goto unmap;
}
get_page(*page);
out:
diff --git a/mm/madvise.c b/mm/madvise.c
index 8eda184..e66ef0a 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -343,7 +343,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
continue;
}
- page = vm_normal_page(vma, addr, ptent);
+ page = _vm_normal_page(vma, addr, ptent, true);
if (!page)
continue;
diff --git a/mm/memory.c b/mm/memory.c
index 471ed99..e7f0a4b 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -789,8 +789,8 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
#else
# define HAVE_PTE_SPECIAL 0
#endif
-struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
- pte_t pte)
+struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
+ pte_t pte, bool with_public_device)
{
unsigned long pfn = pte_pfn(pte);
@@ -801,8 +801,31 @@ struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
return vma->vm_ops->find_special_page(vma, addr);
if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
return NULL;
- if (!is_zero_pfn(pfn))
- print_bad_pte(vma, addr, pte, NULL);
+ if (is_zero_pfn(pfn))
+ return NULL;
+
+ /*
+ * Device public pages are special pages (they are ZONE_DEVICE
+ * pages but different from persistent memory). They behave
+ * allmost like normal pages. The difference is that they are
+ * not on the lru and thus should never be involve with any-
+ * thing that involve lru manipulation (mlock, numa balancing,
+ * ...).
+ *
+ * This is why we still want to return NULL for such page from
+ * vm_normal_page() so that we do not have to special case all
+ * call site of vm_normal_page().
+ */
+ if (likely(pfn < highest_memmap_pfn)) {
+ struct page *page = pfn_to_page(pfn);
+
+ if (is_device_public_page(page)) {
+ if (with_public_device)
+ return page;
+ return NULL;
+ }
+ }
+ print_bad_pte(vma, addr, pte, NULL);
return NULL;
}
@@ -983,6 +1006,19 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
get_page(page);
page_dup_rmap(page, false);
rss[mm_counter(page)]++;
+ } else if (pte_devmap(pte)) {
+ page = pte_page(pte);
+
+ /*
+ * Cache coherent device memory behave like regular page and
+ * not like persistent memory page. For more informations see
+ * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h
+ */
+ if (is_device_public_page(page)) {
+ get_page(page);
+ page_dup_rmap(page, false);
+ rss[mm_counter(page)]++;
+ }
}
out_set_pte:
@@ -1236,7 +1272,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
if (pte_present(ptent)) {
struct page *page;
- page = vm_normal_page(vma, addr, ptent);
+ page = _vm_normal_page(vma, addr, ptent, true);
if (unlikely(details) && page) {
/*
* unmap_shared_mapping_pages() wants to
diff --git a/mm/migrate.c b/mm/migrate.c
index 729f341..9c3c323 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -229,12 +229,19 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,
if (is_write_migration_entry(entry))
pte = maybe_mkwrite(pte, vma);
- if (unlikely(is_zone_device_page(new)) &&
- is_device_private_page(new)) {
- entry = make_device_private_entry(new, pte_write(pte));
- pte = swp_entry_to_pte(entry);
- if (pte_swp_soft_dirty(*pvmw.pte))
- pte = pte_mksoft_dirty(pte);
+ if (unlikely(is_zone_device_page(new))) {
+ if (is_device_private_page(new)) {
+ entry = make_device_private_entry(new, pte_write(pte));
+ pte = swp_entry_to_pte(entry);
+ if (pte_swp_soft_dirty(*pvmw.pte))
+ pte = pte_mksoft_dirty(pte);
+ }
+#if IS_ENABLED(CONFIG_DEVICE_PUBLIC)
+ else if (is_device_public_page(new)) {
+ pte = pte_mkdevmap(pte);
+ flush_dcache_page(new);
+ }
+#endif /* IS_ENABLED(CONFIG_DEVICE_PUBLIC) */
} else
flush_dcache_page(new);
@@ -408,12 +415,11 @@ int migrate_page_move_mapping(struct address_space *mapping,
void **pslot;
/*
- * ZONE_DEVICE pages have 1 refcount always held by their device
- *
- * Note that DAX memory will never reach that point as it does not have
- * the MEMORY_DEVICE_ALLOW_MIGRATE flag set (see memory_hotplug.h).
+ * Device public or private pages have an extra refcount as they are
+ * ZONE_DEVICE pages.
*/
- expected_count += is_zone_device_page(page);
+ expected_count += is_device_private_page(page);
+ expected_count += is_device_public_page(page);
if (!mapping) {
/* Anonymous page without mapping */
@@ -2098,7 +2104,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
#endif /* CONFIG_NUMA */
-
struct migrate_vma {
struct vm_area_struct *vma;
unsigned long *dst;
@@ -2177,7 +2182,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
if (is_write_device_private_entry(entry))
mpfn |= MIGRATE_PFN_WRITE;
} else {
- page = vm_normal_page(migrate->vma, addr, pte);
+ page = _vm_normal_page(migrate->vma, addr, pte, true);
mpfn = migrate_pfn(pfn) | MIGRATE_PFN_MIGRATE;
mpfn |= pte_write(pte) ? MIGRATE_PFN_WRITE : 0;
}
@@ -2302,13 +2307,18 @@ static bool migrate_vma_check_page(struct page *page)
/* Page from ZONE_DEVICE have one extra reference */
if (is_zone_device_page(page)) {
- if (is_device_private_page(page)) {
+ if (is_device_private_page(page) ||
+ is_device_public_page(page))
extra++;
- } else
+ else
/* Other ZONE_DEVICE memory type are not supported */
return false;
}
+ /* For file back page */
+ if (page_mapping(page))
+ extra += 1 + page_has_private(page);
+
if ((page_count(page) - extra) > page_mapcount(page))
return false;
@@ -2532,11 +2542,21 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate,
*/
__SetPageUptodate(page);
- if (is_zone_device_page(page) && is_device_private_page(page)) {
- swp_entry_t swp_entry;
+ if (is_zone_device_page(page)) {
+ if (is_device_private_page(page)) {
+ swp_entry_t swp_entry;
- swp_entry = make_device_private_entry(page, vma->vm_flags & VM_WRITE);
- entry = swp_entry_to_pte(swp_entry);
+ swp_entry = make_device_private_entry(page, vma->vm_flags & VM_WRITE);
+ entry = swp_entry_to_pte(swp_entry);
+ }
+#if IS_ENABLED(CONFIG_DEVICE_PUBLIC)
+ else if (is_device_public_page(page)) {
+ entry = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
+ if (vma->vm_flags & VM_WRITE)
+ entry = pte_mkwrite(pte_mkdirty(entry));
+ entry = pte_mkdevmap(entry);
+ }
+#endif /* IS_ENABLED(CONFIG_DEVICE_PUBLIC) */
} else {
entry = mk_pte(page, vma->vm_page_prot);
if (vma->vm_flags & VM_WRITE)
@@ -2623,7 +2643,7 @@ static void migrate_vma_pages(struct migrate_vma *migrate)
migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
continue;
}
- } else {
+ } else if (!is_device_public_page(newpage)) {
/*
* Other types of ZONE_DEVICE page are not
* supported.
diff --git a/mm/swap.c b/mm/swap.c
index 4f44dbd..212370d 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -760,6 +760,17 @@ void release_pages(struct page **pages, int nr, bool cold)
if (is_huge_zero_page(page))
continue;
+ /* Device public page can not be huge page */
+ if (is_device_public_page(page)) {
+ if (locked_pgdat) {
+ spin_unlock_irqrestore(&locked_pgdat->lru_lock,
+ flags);
+ locked_pgdat = NULL;
+ }
+ put_zone_device_private_or_public_page(page);
+ continue;
+ }
+
page = compound_head(page);
if (!put_page_testzero(page))
continue;
--
2.9.3
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