This patch implements charge and uncharge of swapcgroup.
- what will be charged ?
charge the number of swap entries in bytes.
- when to charge/uncharge ?
charge at get_swap_entry(), and uncharge at swap_entry_free().
- to what group charge the swap entry ?
To determine to what mem_cgroup the swap entry should be charged,
I changed the argument of get_swap_entry() from (void) to
(struct page *). As a result, get_swap_entry() can determine
to what mem_cgroup it should charge the swap entry
by referring to page->page_cgroup->mem_cgroup.
- from what group uncharge the swap entry ?
I added in previous patch to swap_info_struct a member
'struct swap_cgroup **', array of pointer to which swap_cgroup
the swap entry is charged.
Change log
v2->v3
- Rebased on 2.6.26-rc5-mm3
- make swap_cgroup_charge() fail when !pc.
- add check on mem_cgroup_subsys.disabled
v1->v2
- Rebased on 2.6.26-rc2-mm1
- Implemented as a add-on to memory cgroup.
Signed-off-by: Daisuke Nishimura <[EMAIL PROTECTED]>
---
include/linux/memcontrol.h | 17 ++++++++++++++
include/linux/swap.h | 4 +-
mm/memcontrol.c | 53 ++++++++++++++++++++++++++++++++++++++++++++
mm/shmem.c | 2 +-
mm/swap_state.c | 2 +-
mm/swapfile.c | 13 ++++++++++-
6 files changed, 86 insertions(+), 5 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index b6ff509..f3c84f7 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -170,6 +170,11 @@ static inline long mem_cgroup_calc_reclaim(struct
mem_cgroup *mem,
extern struct mem_cgroup **swap_info_clear_memcg(struct swap_info_struct *p);
extern int swap_info_alloc_memcg(struct swap_info_struct *p,
unsigned long maxpages);
+extern int swap_cgroup_charge(struct page *page,
+ struct swap_info_struct *si,
+ unsigned long offset);
+extern void swap_cgroup_uncharge(struct swap_info_struct *si,
+ unsigned long offset);
#else
static inline
struct mem_cgroup **swap_info_clear_memcg(struct swap_info_struct *p)
@@ -182,6 +187,18 @@ int swap_info_alloc_memcg(struct swap_info_struct *p,
unsigned long maxpages)
{
return 0;
}
+
+static inline int swap_cgroup_charge(struct page *page,
+ struct swap_info_struct *si,
+ unsigned long offset)
+{
+ return 0;
+}
+
+static inline void swap_cgroup_uncharge(struct swap_info_struct *si,
+ unsigned long offset)
+{
+}
#endif
#endif /* _LINUX_MEMCONTROL_H */
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 6e1b03d..f80255b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -298,7 +298,7 @@ extern struct page *swapin_readahead(swp_entry_t, gfp_t,
/* linux/mm/swapfile.c */
extern long total_swap_pages;
extern void si_swapinfo(struct sysinfo *);
-extern swp_entry_t get_swap_page(void);
+extern swp_entry_t get_swap_page(struct page *);
extern swp_entry_t get_swap_page_of_type(int);
extern int swap_duplicate(swp_entry_t);
extern int valid_swaphandles(swp_entry_t, unsigned long *);
@@ -405,7 +405,7 @@ static inline int remove_exclusive_swap_page_ref(struct
page *page)
return 0;
}
-static inline swp_entry_t get_swap_page(void)
+static inline swp_entry_t get_swap_page(struct page *page)
{
swp_entry_t entry;
entry.val = 0;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 81bb7fa..d16d0a5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1243,5 +1243,58 @@ int swap_info_alloc_memcg(struct swap_info_struct *p,
unsigned long maxpages)
out:
return ret;
}
+
+int swap_cgroup_charge(struct page *page,
+ struct swap_info_struct *si,
+ unsigned long offset)
+{
+ int ret;
+ struct page_cgroup *pc;
+ struct mem_cgroup *mem;
+
+ if (mem_cgroup_subsys.disabled)
+ return 0;
+
+ lock_page_cgroup(page);
+ pc = page_get_page_cgroup(page);
+ if (unlikely(!pc)) {
+ /* make get_swap_page fail */
+ unlock_page_cgroup(page);
+ return -ENOMEM;
+ } else {
+ mem = pc->mem_cgroup;
+ css_get(&mem->css);
+ }
+ unlock_page_cgroup(page);
+
+ ret = res_counter_charge(&mem->swap_res, PAGE_SIZE);
+ if (!ret)
+ si->memcg[offset] = mem;
+ else
+ css_put(&mem->css);
+
+ return ret;
+}
+
+void swap_cgroup_uncharge(struct swap_info_struct *si,
+ unsigned long offset)
+{
+ struct mem_cgroup *mem = si->memcg[offset];
+
+ if (mem_cgroup_subsys.disabled)
+ return;
+
+ /* "mem" would be NULL:
+ * 1. when get_swap_page() failed at charging swap_cgroup,
+ * and called swap_entry_free().
+ * 2. when this swap entry had been assigned by
+ * get_swap_page_of_type() (via SWSUSP?).
+ */
+ if (mem) {
+ res_counter_uncharge(&mem->swap_res, PAGE_SIZE);
+ si->memcg[offset] = NULL;
+ css_put(&mem->css);
+ }
+}
#endif
diff --git a/mm/shmem.c b/mm/shmem.c
index bed732c..958e041 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1029,7 +1029,7 @@ static int shmem_writepage(struct page *page, struct
writeback_control *wbc)
* want to check if there's a redundant swappage to be discarded.
*/
if (wbc->for_reclaim)
- swap = get_swap_page();
+ swap = get_swap_page(page);
else
swap.val = 0;
diff --git a/mm/swap_state.c b/mm/swap_state.c
index ca43e64..ad5d85c 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -138,7 +138,7 @@ int add_to_swap(struct page * page, gfp_t gfp_mask)
BUG_ON(!PageUptodate(page));
for (;;) {
- entry = get_swap_page();
+ entry = get_swap_page(page);
if (!entry.val)
return 0;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 312c573..57798c5 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -172,7 +172,9 @@ no_page:
return 0;
}
-swp_entry_t get_swap_page(void)
+/* get_swap_page() calls this */
+static int swap_entry_free(struct swap_info_struct *, unsigned long);
+swp_entry_t get_swap_page(struct page *page)
{
struct swap_info_struct *si;
pgoff_t offset;
@@ -201,6 +203,14 @@ swp_entry_t get_swap_page(void)
swap_list.next = next;
offset = scan_swap_map(si);
if (offset) {
+ /*
+ * This should be the first use of this swap entry.
+ * So, charge this swap entry here.
+ */
+ if (swap_cgroup_charge(page, si, offset)) {
+ swap_entry_free(si, offset);
+ goto noswap;
+ }
spin_unlock(&swap_lock);
return swp_entry(type, offset);
}
@@ -285,6 +295,7 @@ static int swap_entry_free(struct swap_info_struct *p,
unsigned long offset)
swap_list.next = p - swap_info;
nr_swap_pages++;
p->inuse_pages--;
+ swap_cgroup_uncharge(p, offset);
}
}
return count;
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