[PATCH 13/18] mm: memcontrol: drop unused try/commit/cancel charge API

Johannes Weiner
2020-04-20T22:12:27Z

There are no more users. RIP in peace.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
include/linux/memcontrol.h | 36 -----------
mm/memcontrol.c | 126 +++++--------------------------------
2 files changed, 15 insertions(+), 147 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 9ac8122ec1cd..52eb6411cfee 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -357,14 +357,6 @@ static inline unsigned long mem_cgroup_protection(struct mem_cgroup *memcg,
enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
struct mem_cgroup *memcg);

-int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
- gfp_t gfp_mask, struct mem_cgroup **memcgp);
-int mem_cgroup_try_charge_delay(struct page *page, struct mm_struct *mm,
- gfp_t gfp_mask, struct mem_cgroup **memcgp);
-void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
- bool lrucare);
-void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg);
-
int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask,
bool lrucare);

@@ -846,34 +838,6 @@ static inline enum mem_cgroup_protection mem_cgroup_protected(
return MEMCG_PROT_NONE;
}

-static inline int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
- gfp_t gfp_mask,
- struct mem_cgroup **memcgp)
-{
- *memcgp = NULL;
- return 0;
-}
-
-static inline int mem_cgroup_try_charge_delay(struct page *page,
- struct mm_struct *mm,
- gfp_t gfp_mask,
- struct mem_cgroup **memcgp)
-{
- *memcgp = NULL;
- return 0;
-}
-
-static inline void mem_cgroup_commit_charge(struct page *page,
- struct mem_cgroup *memcg,
- bool lrucare)
-{
-}
-
-static inline void mem_cgroup_cancel_charge(struct page *page,
- struct mem_cgroup *memcg)
-{
-}
-
static inline int mem_cgroup_charge(struct page *page, struct mm_struct *mm,
gfp_t gfp_mask, bool lrucare)
{
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 7845a87b94d5..d5aee5577ff3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6431,29 +6431,26 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
}

/**
- * mem_cgroup_try_charge - try charging a page
+ * mem_cgroup_charge - charge a newly allocated page to a cgroup
* @page: page to charge
* @mm: mm context of the victim
* @gfp_mask: reclaim mode
- * @memcgp: charged memcg return
+ * @lrucare: page might be on the LRU already
*
* Try to charge @page to the memcg that @mm belongs to, reclaiming
* pages according to @gfp_mask if necessary.
*
- * Returns 0 on success, with *@memcgp pointing to the charged memcg.
- * Otherwise, an error code is returned.
- *
- * After page->mapping has been set up, the caller must finalize the
- * charge with mem_cgroup_commit_charge(). Or abort the transaction
- * with mem_cgroup_cancel_charge() in case page instantiation fails.
+ * Returns 0 on success. Otherwise, an error code is returned.
*/
-int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
- gfp_t gfp_mask, struct mem_cgroup **memcgp)
+int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask,
+ bool lrucare)
{
unsigned int nr_pages = hpage_nr_pages(page);
struct mem_cgroup *memcg = NULL;
int ret = 0;

+ VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page);
+
if (mem_cgroup_disabled())
goto out;

@@ -6485,56 +6482,8 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
memcg = get_mem_cgroup_from_mm(mm);

ret = try_charge(memcg, gfp_mask, nr_pages);
-
- css_put(&memcg->css);
-out:
- *memcgp = memcg;
- return ret;
-}
-
-int mem_cgroup_try_charge_delay(struct page *page, struct mm_struct *mm,
- gfp_t gfp_mask, struct mem_cgroup **memcgp)
-{
- int ret;
-
- ret = mem_cgroup_try_charge(page, mm, gfp_mask, memcgp);
- if (*memcgp)
- cgroup_throttle_swaprate(page, gfp_mask);
- return ret;
-}
-
-/**
- * mem_cgroup_commit_charge - commit a page charge
- * @page: page to charge
- * @memcg: memcg to charge the page to
- * @lrucare: page might be on LRU already
- *
- * Finalize a charge transaction started by mem_cgroup_try_charge(),
- * after page->mapping has been set up. This must happen atomically
- * as part of the page instantiation, i.e. under the page table lock
- * for anonymous pages, under the page lock for page and swap cache.
- *
- * In addition, the page must not be on the LRU during the commit, to
- * prevent racing with task migration. If it might be, use @lrucare.
- *
- * Use mem_cgroup_cancel_charge() to cancel the transaction instead.
- */
-void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
- bool lrucare)
-{
- unsigned int nr_pages = hpage_nr_pages(page);
-
- VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page);
-
- if (mem_cgroup_disabled())
- return;
- /*
- * Swap faults will attempt to charge the same page multiple
- * times. But reuse_swap_page() might have removed the page
- * from swapcache already, so we can't check PageSwapCache().
- */
- if (!memcg)
- return;
+ if (ret)
+ goto out_put;

commit_charge(page, memcg, lrucare);

@@ -6552,55 +6501,11 @@ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
*/
mem_cgroup_uncharge_swap(entry, nr_pages);
}
-}

-/**
- * mem_cgroup_cancel_charge - cancel a page charge
- * @page: page to charge
- * @memcg: memcg to charge the page to
- *
- * Cancel a charge transaction started by mem_cgroup_try_charge().
- */
-void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg)
-{
- unsigned int nr_pages = hpage_nr_pages(page);
-
- if (mem_cgroup_disabled())
- return;
- /*
- * Swap faults will attempt to charge the same page multiple
- * times. But reuse_swap_page() might have removed the page
- * from swapcache already, so we can't check PageSwapCache().
- */
- if (!memcg)
- return;
-
- cancel_charge(memcg, nr_pages);
-}
-
-/**
- * mem_cgroup_charge - charge a newly allocated page to a cgroup
- * @page: page to charge
- * @mm: mm context of the victim
- * @gfp_mask: reclaim mode
- * @lrucare: page might be on the LRU already
- *
- * Try to charge @page to the memcg that @mm belongs to, reclaiming
- * pages according to @gfp_mask if necessary.
- *
- * Returns 0 on success. Otherwise, an error code is returned.
- */
-int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask,
- bool lrucare)
-{
- struct mem_cgroup *memcg;
- int ret;
-
- ret = mem_cgroup_try_charge(page, mm, gfp_mask, &memcg);
- if (ret)
- return ret;
- mem_cgroup_commit_charge(page, memcg, lrucare);
- return 0;
+out_put:
+ css_put(&memcg->css);
+out:
+ return ret;
}

struct uncharge_gather {
@@ -6707,8 +6612,7 @@ static void uncharge_list(struct list_head *page_list)
* mem_cgroup_uncharge - uncharge a page
* @page: page to uncharge
*
- * Uncharge a page previously charged with mem_cgroup_try_charge() and
- * mem_cgroup_commit_charge().
+ * Uncharge a page previously charged with mem_cgroup_charge().
*/
void mem_cgroup_uncharge(struct page *page)
{
@@ -6731,7 +6635,7 @@ void mem_cgroup_uncharge(struct page *page)
* @page_list: list of pages to uncharge
*
* Uncharge a list of pages previously charged with
- * mem_cgroup_try_charge() and mem_cgroup_commit_charge().
+ * mem_cgroup_charge().
*/
void mem_cgroup_uncharge_list(struct list_head *page_list)
{
--
2.26.0