[PATCH v3 2/2] mm/memcg: Consolidate mem_cgroup_resize_[memsw]_limit() functions.

[Andrey Ryabinin]

mem_cgroup_resize_limit() and mem_cgroup_resize_memsw_limit() are almost
identical functions. Instead of having two of them, we could pass an
additional argument to mem_cgroup_resize_limit() and by using it,
consolidate all the code in a single function.

Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
---
 mm/memcontrol.c | 61 +++++++++++++--------------------------------------------
 1 file changed, 14 insertions(+), 47 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0d26db9a665d..f6253c80a5c8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2445,50 +2445,17 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
 
 static DEFINE_MUTEX(memcg_limit_mutex);
 
-static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
-				   unsigned long limit)
+static bool invalid_mem_limit(struct mem_cgroup *memcg, bool memsw,
+			      unsigned long limit)
 {
-	unsigned long usage;
-	bool enlarge = false;
-	int ret;
-
-	do {
-		if (signal_pending(current)) {
-			ret = -EINTR;
-			break;
-		}
-
-		mutex_lock(&memcg_limit_mutex);
-		if (limit > memcg->memsw.limit) {
-			mutex_unlock(&memcg_limit_mutex);
-			ret = -EINVAL;
-			break;
-		}
-		if (limit > memcg->memory.limit)
-			enlarge = true;
-		ret = page_counter_limit(&memcg->memory, limit);
-		mutex_unlock(&memcg_limit_mutex);
-
-		if (!ret)
-			break;
-
-		usage = page_counter_read(&memcg->memory);
-		if (!try_to_free_mem_cgroup_pages(memcg, usage - limit,
-					GFP_KERNEL, true)) {
-			ret = -EBUSY;
-			break;
-		}
-	} while (true);
-
-	if (!ret && enlarge)
-		memcg_oom_recover(memcg);
-
-	return ret;
+	return (!memsw && limit > memcg->memsw.limit) ||
+		(memsw && limit < memcg->memory.limit);
 }
 
-static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
-					 unsigned long limit)
+static int mem_cgroup_resize_limit(struct mem_cgroup *memcg, bool memsw,
+				   unsigned long limit)
 {
+	struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory;
 	unsigned long usage;
 	bool enlarge = false;
 	int ret;
@@ -2500,22 +2467,22 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
 		}
 
 		mutex_lock(&memcg_limit_mutex);
-		if (limit < memcg->memory.limit) {
+		if (invalid_mem_limit(memcg, memsw, limit)) {
 			mutex_unlock(&memcg_limit_mutex);
 			ret = -EINVAL;
 			break;
 		}
-		if (limit > memcg->memsw.limit)
+		if (limit > counter->limit)
 			enlarge = true;
-		ret = page_counter_limit(&memcg->memsw, limit);
+		ret = page_counter_limit(counter, limit);
 		mutex_unlock(&memcg_limit_mutex);
 
 		if (!ret)
 			break;
 
-		usage = page_counter_read(&memcg->memsw);
+		usage = page_counter_read(counter);
 		if (!try_to_free_mem_cgroup_pages(memcg, usage - limit,
-					GFP_KERNEL, false)) {
+					GFP_KERNEL, !memsw)) {
 			ret = -EBUSY;
 			break;
 		}
@@ -3193,10 +3160,10 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
 		}
 		switch (MEMFILE_TYPE(of_cft(of)->private)) {
 		case _MEM:
-			ret = mem_cgroup_resize_limit(memcg, nr_pages);
+			ret = mem_cgroup_resize_limit(memcg, false, nr_pages);
 			break;
 		case _MEMSWAP:
-			ret = mem_cgroup_resize_memsw_limit(memcg, nr_pages);
+			ret = mem_cgroup_resize_limit(memcg, true, nr_pages);
 			break;
 		case _KMEM:
 			ret = memcg_update_kmem_limit(memcg, nr_pages);
-- 
2.13.6