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authorJérôme Glisse <jglisse@redhat.com>2017-06-09 19:01:23 -0400
committerJérôme Glisse <jglisse@redhat.com>2017-08-09 18:13:29 -0400
commitb8fd761ba942e6dde8edbcec9302fb74b4f1a618 (patch)
treec24b90ec950c820f9544f493088eb0bae7a13a12
parent86d512608be4bb112276ce5aa23260a733346ec7 (diff)
mm/memcontrol: support MEMORY_DEVICE_PRIVATE v4
HMM pages (private or public device pages) are ZONE_DEVICE page and thus need special handling when it comes to lru or refcount. This patch make sure that memcontrol properly handle those when it face them. Those pages are use like regular pages in a process address space either as anonymous page or as file back page. So from memcg point of view we want to handle them like regular page for now at least. Changed since v3: - remove public support and move those chunk to separate patch Changed since v2: - s/host/public Changed since v1: - s/public/host - add comments explaining how device memory behave and why Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Acked-by: Balbir Singh <bsingharora@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: cgroups@vger.kernel.org
-rw-r--r--kernel/memremap.c1
-rw-r--r--mm/memcontrol.c52
2 files changed, 49 insertions, 4 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 1b084ca85b88..6b601e4ca87f 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -480,6 +480,7 @@ void put_zone_device_private_page(struct page *page)
__ClearPageWaiters(page);
page->mapping = NULL;
+ mem_cgroup_uncharge(page);
page->pgmap->page_free(page, page->pgmap->data);
} else if (!count)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c709fdceac13..f9f369dc91aa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4391,12 +4391,13 @@ enum mc_target_type {
MC_TARGET_NONE = 0,
MC_TARGET_PAGE,
MC_TARGET_SWAP,
+ MC_TARGET_DEVICE,
};
static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
unsigned long addr, pte_t ptent)
{
- struct page *page = vm_normal_page(vma, addr, ptent);
+ struct page *page = _vm_normal_page(vma, addr, ptent, true);
if (!page || !page_mapped(page))
return NULL;
@@ -4413,7 +4414,7 @@ static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
return page;
}
-#ifdef CONFIG_SWAP
+#if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE)
static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
pte_t ptent, swp_entry_t *entry)
{
@@ -4422,6 +4423,23 @@ static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
if (!(mc.flags & MOVE_ANON) || non_swap_entry(ent))
return NULL;
+
+ /*
+ * Handle MEMORY_DEVICE_PRIVATE which are ZONE_DEVICE page belonging to
+ * a device and because they are not accessible by CPU they are store
+ * as special swap entry in the CPU page table.
+ */
+ if (is_device_private_entry(ent)) {
+ page = device_private_entry_to_page(ent);
+ /*
+ * MEMORY_DEVICE_PRIVATE means ZONE_DEVICE page and which have
+ * a refcount of 1 when free (unlike normal page)
+ */
+ if (!page_ref_add_unless(page, 1, 1))
+ return NULL;
+ return page;
+ }
+
/*
* Because lookup_swap_cache() updates some statistics counter,
* we call find_get_page() with swapper_space directly.
@@ -4582,6 +4600,12 @@ out:
* 2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
* target for charge migration. if @target is not NULL, the entry is stored
* in target->ent.
+ * 3(MC_TARGET_DEVICE): like MC_TARGET_PAGE but page is MEMORY_DEVICE_PRIVATE
+ * (so ZONE_DEVICE page and thus not on the lru). For now we such page is
+ * charge like a regular page would be as for all intent and purposes it is
+ * just special memory taking the place of a regular page.
+ *
+ * See Documentations/vm/hmm.txt and include/linux/hmm.h
*
* Called with pte lock held.
*/
@@ -4610,6 +4634,8 @@ static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
*/
if (page->mem_cgroup == mc.from) {
ret = MC_TARGET_PAGE;
+ if (is_device_private_page(page))
+ ret = MC_TARGET_DEVICE;
if (target)
target->page = page;
}
@@ -4669,6 +4695,11 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
ptl = pmd_trans_huge_lock(pmd, vma);
if (ptl) {
+ /*
+ * Note their can not be MC_TARGET_DEVICE for now as we do not
+ * support transparent huge page with MEMORY_DEVICE_PUBLIC or
+ * MEMORY_DEVICE_PRIVATE but this might change.
+ */
if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
mc.precharge += HPAGE_PMD_NR;
spin_unlock(ptl);
@@ -4884,6 +4915,14 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
putback_lru_page(page);
}
put_page(page);
+ } else if (target_type == MC_TARGET_DEVICE) {
+ page = target.page;
+ if (!mem_cgroup_move_account(page, true,
+ mc.from, mc.to)) {
+ mc.precharge -= HPAGE_PMD_NR;
+ mc.moved_charge += HPAGE_PMD_NR;
+ }
+ put_page(page);
}
spin_unlock(ptl);
return 0;
@@ -4895,12 +4934,16 @@ retry:
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (; addr != end; addr += PAGE_SIZE) {
pte_t ptent = *(pte++);
+ bool device = false;
swp_entry_t ent;
if (!mc.precharge)
break;
switch (get_mctgt_type(vma, addr, ptent, &target)) {
+ case MC_TARGET_DEVICE:
+ device = true;
+ /* fall through */
case MC_TARGET_PAGE:
page = target.page;
/*
@@ -4911,7 +4954,7 @@ retry:
*/
if (PageTransCompound(page))
goto put;
- if (isolate_lru_page(page))
+ if (!device && isolate_lru_page(page))
goto put;
if (!mem_cgroup_move_account(page, false,
mc.from, mc.to)) {
@@ -4919,7 +4962,8 @@ retry:
/* we uncharge from mc.from later. */
mc.moved_charge++;
}
- putback_lru_page(page);
+ if (!device)
+ putback_lru_page(page);
put: /* get_mctgt_type() gets the page */
put_page(page);
break;