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mm/device-public-memory: device memory cache coherent with CPU

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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.

Link: http://lkml.kernel.org/r/20170817000548.32038-19-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jérôme Glisse
2017-09-08 16:12:24 -07:00
committed by Linus Torvalds
parent 8315ada7f0
commit df6ad69838
14 changed files with 158 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files

55
mm/migrate.c
View File

@@ -36,6 +36,7 @@
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>
#include <linux/gfp.h>
#include <linux/pfn_t.h>
#include <linux/memremap.h>
#include <linux/userfaultfd_k.h>
#include <linux/balloon_compaction.h>
@@ -239,10 +240,14 @@ 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 (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);
} else if (is_device_public_page(new)) {
pte = pte_mkdevmap(pte);
flush_dcache_page(new);
}
} else
flush_dcache_page(new);
@@ -437,12 +442,11 @@ 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 */
@@ -2123,7 +2127,6 @@ out_unlock:
#endif /* CONFIG_NUMA */
struct migrate_vma {
struct vm_area_struct *vma;
unsigned long *dst;
@@ -2263,7 +2266,7 @@ again:
pfn = 0;
goto next;
}
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;
}
@@ -2406,10 +2409,19 @@ static bool migrate_vma_check_page(struct page *page)
if (is_device_private_page(page))
return true;
/* Other ZONE_DEVICE memory type are not supported */
return false;
/*
* Only allow device public page to be migrated and account for
* the extra reference count imply by ZONE_DEVICE pages.
*/
if (!is_device_public_page(page))
return false;
extra++;
}
/* For file back page */
if (page_mapping(page))
extra += 1 + page_has_private(page);
if ((page_count(page) - extra) > page_mapcount(page))
return false;
@@ -2647,11 +2659,18 @@ 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);
} 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);
}
} else {
entry = mk_pte(page, vma->vm_page_prot);
if (vma->vm_flags & VM_WRITE)
@@ -2768,7 +2787,7 @@ 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.