This patch adds support for moving charge of shmem and swap of it. It's enabled
by setting bit 2 of <target cgroup>/memory.move_charge_at_immigrate.
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
---
Documentation/cgroups/memory.txt | 7 +++-
include/linux/swap.h | 5 +++
mm/memcontrol.c | 52 +++++++++++++++++++++++++------------
mm/shmem.c | 37 +++++++++++++++++++++++++++
4 files changed, 82 insertions(+), 19 deletions(-)
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index f53d220..b197d60 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -464,13 +464,16 @@ charges should be moved.
-----+------------------------------------------------------------------------
1 | A charge of file cache mmap'ed by the target task. Those pages must be
| mmap'ed only by the target task.
+ -----+------------------------------------------------------------------------
+ 2 | A charge of a tmpfs page(or swap of it) mmap'ed by the target task. A
+ | typical use case of it is ipc shared memory. It must be mmap'ed by the
+ | target task, but unlike above 2 cases, the task may not be the only one.
+ | You must enable Swap Extension(see 2.4) to enable move of swap charges.
Note: Those pages and swaps must be charged to the old cgroup.
-Note: More type of pages(e.g. shmem) will be supported by other bits in future.
8.3 TODO
-- Add support for other types of pages(e.g. file cache, shmem, etc.).
- Implement madvise(2) to let users decide the vma to be moved or not to be
moved.
- All of moving charge operations are done under cgroup_mutex. It's not good
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 1f59d93..94ec325 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -285,6 +285,11 @@ extern void kswapd_stop(int nid);
extern int shmem_unuse(swp_entry_t entry, struct page *page);
#endif /* CONFIG_MMU */
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+extern void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
+ struct page **pagep, swp_entry_t *ent);
+#endif
+
extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
#ifdef CONFIG_SWAP
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 66d2704..99a496c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -251,6 +251,7 @@ struct mem_cgroup {
enum move_type {
MOVE_CHARGE_TYPE_ANON, /* private anonymous page and swap of it */
MOVE_CHARGE_TYPE_FILE, /* private file caches */
+ MOVE_CHARGE_TYPE_SHMEM, /* shared memory and swap of it */
NR_MOVE_TYPE,
};
@@ -4195,12 +4196,30 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
&mc.to->move_charge_at_immigrate);
bool move_file = test_bit(MOVE_CHARGE_TYPE_FILE,
&mc.to->move_charge_at_immigrate);
+ bool move_shmem = test_bit(MOVE_CHARGE_TYPE_SHMEM,
+ &mc.to->move_charge_at_immigrate);
+ bool is_shmem = false;
if (!pte_present(ptent)) {
- /* TODO: handle swap of shmes/tmpfs */
- if (pte_none(ptent) || pte_file(ptent))
- return 0;
- else if (is_swap_pte(ptent)) {
+ if (pte_none(ptent) || pte_file(ptent)) {
+ struct inode *inode;
+ struct address_space *mapping;
+ pgoff_t pgoff = 0;
+
+ if (!vma->vm_file)
+ return 0;
+ mapping = vma->vm_file->f_mapping;
+ if (!move_shmem || !mapping_cap_swap_backed(mapping))
+ return 0;
+
+ if (pte_none(ptent))
+ pgoff = linear_page_index(vma, addr);
+ if (pte_file(ptent))
+ pgoff = pte_to_pgoff(ptent);
+ inode = vma->vm_file->f_path.dentry->d_inode;
+ mem_cgroup_get_shmem_target(inode, pgoff, &page, &ent);
+ is_shmem = true;
+ } else if (is_swap_pte(ptent)) {
ent = pte_to_swp_entry(ptent);
if (!move_anon || non_swap_entry(ent))
return 0;
@@ -4210,26 +4229,22 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
page = vm_normal_page(vma, addr, ptent);
if (!page || !page_mapped(page))
return 0;
- /*
- * TODO: We don't move charges of shmem/tmpfs pages for now.
- */
if (PageAnon(page)) {
if (!move_anon)
return 0;
} else if (page_is_file_cache(page)) {
if (!move_file)
return 0;
- } else
- return 0;
+ } else {
+ if (!move_shmem)
+ return 0;
+ is_shmem = true;
+ }
if (!get_page_unless_zero(page))
return 0;
usage_count = page_mapcount(page);
}
- if (usage_count > 1) {
- /*
- * TODO: We don't move charges of shared(used by multiple
- * processes) pages for now.
- */
+ if (usage_count > 1 && !is_shmem) {
if (page)
put_page(page);
return 0;
@@ -4284,6 +4299,8 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
down_read(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ bool move_shmem = test_bit(MOVE_CHARGE_TYPE_SHMEM,
+ &mc.to->move_charge_at_immigrate);
struct mm_walk mem_cgroup_count_precharge_walk = {
.pmd_entry = mem_cgroup_count_precharge_pte_range,
.mm = mm,
@@ -4292,7 +4309,7 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
if (is_vm_hugetlb_page(vma))
continue;
/* TODO: We don't move charges of shmem/tmpfs pages for now. */
- if (vma->vm_flags & VM_SHARED)
+ if ((vma->vm_flags & VM_SHARED) && !move_shmem)
continue;
walk_page_range(vma->vm_start, vma->vm_end,
&mem_cgroup_count_precharge_walk);
@@ -4483,6 +4500,8 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
down_read(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
int ret;
+ bool move_shmem = test_bit(MOVE_CHARGE_TYPE_SHMEM,
+ &mc.to->move_charge_at_immigrate);
struct mm_walk mem_cgroup_move_charge_walk = {
.pmd_entry = mem_cgroup_move_charge_pte_range,
.mm = mm,
@@ -4490,8 +4509,7 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
};
if (is_vm_hugetlb_page(vma))
continue;
- /* TODO: We don't move charges of shmem/tmpfs pages for now. */
- if (vma->vm_flags & VM_SHARED)
+ if ((vma->vm_flags & VM_SHARED) && !move_shmem)
continue;
ret = walk_page_range(vma->vm_start, vma->vm_end,
&mem_cgroup_move_charge_walk);
diff --git a/mm/shmem.c b/mm/shmem.c
index dde4363..cb87365 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2701,3 +2701,40 @@ int shmem_zero_setup(struct vm_area_struct *vma)
vma->vm_ops = &shmem_vm_ops;
return 0;
}
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+/**
+ * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
+ * @inode: the inode to be searched
+ * @pgoff: the offset to be searched
+ * @pagep: the pointer for the found page to be stored
+ * @ent: the pointer for the found swap entry to be stored
+ *
+ * If a page is found, refcount of it is incremented. Callers should handle
+ * these refcount.
+ */
+void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
+ struct page **pagep, swp_entry_t *ent)
+{
+ swp_entry_t entry = { .val = 0 }, *ptr;
+ struct page *page = NULL;
+ struct shmem_inode_info *info = SHMEM_I(inode);
+
+ if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+ goto out;
+
+ spin_lock(&info->lock);
+ ptr = shmem_swp_entry(info, pgoff, NULL);
+ if (ptr && ptr->val) {
+ entry.val = ptr->val;
+ page = find_get_page(&swapper_space, entry.val);
+ } else
+ page = find_get_page(inode->i_mapping, pgoff);
+ if (ptr)
+ shmem_swp_unmap(ptr);
+ spin_unlock(&info->lock);
+out:
+ *pagep = page;
+ *ent = entry;
+}
+#endif
--
1.6.4
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