[PATCH] mm/percpu: clean up callers of pcpu_obj_full_size()

[Joshua Hahn]

The size of a pcpu allocation can be interpreted in two ways:
1. The size of the allocation attributable to a single CPU.
2. The total size of the allocation across all CPUs, including the
   allocation overhead (for obj_cgroup membership).

In most accounting paths for percpu memory, we need the second
definition (total size). Make this more obvious by coalescing the
callers of pcpu_obj_full_size().

No functional changes intended.

Signed-off-by: Joshua Hahn <joshua.hahnjy@xxxxxxxxx>
---
 mm/percpu.c | 39 +++++++++++++++++++--------------------
 1 file changed, 19 insertions(+), 20 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index d7883507dc151..76848e096caee 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1623,7 +1623,7 @@ static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
 	if (!objcg || obj_cgroup_is_root(objcg))
 		return true;
 
-	if (obj_cgroup_charge(objcg, gfp, pcpu_obj_full_size(size)))
+	if (obj_cgroup_charge(objcg, gfp, size))
 		return false;
 
 	*objcgp = objcg;
@@ -1642,11 +1642,10 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
 		chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup = objcg;
 
 		rcu_read_lock();
-		mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
-				pcpu_obj_full_size(size));
+		mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B, size);
 		rcu_read_unlock();
 	} else {
-		obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));
+		obj_cgroup_uncharge(objcg, size);
 	}
 }
 
@@ -1662,11 +1661,10 @@ static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
 		return;
 	chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].cgroup = NULL;
 
-	obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));
+	obj_cgroup_uncharge(objcg, size);
 
 	rcu_read_lock();
-	mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
-			-pcpu_obj_full_size(size));
+	mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B, -size);
 	rcu_read_unlock();
 
 	obj_cgroup_put(objcg);
@@ -1696,15 +1694,14 @@ static void pcpu_alloc_tag_alloc_hook(struct pcpu_chunk *chunk, int off,
 {
 	if (mem_alloc_profiling_enabled() && likely(chunk->obj_exts)) {
 		alloc_tag_add(&chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].tag,
-			      current->alloc_tag, pcpu_obj_full_size(size));
+			      current->alloc_tag, size);
 	}
 }
 
 static void pcpu_alloc_tag_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
 {
 	if (mem_alloc_profiling_enabled() && likely(chunk->obj_exts))
-		alloc_tag_sub(&chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].tag,
-			      pcpu_obj_full_size(size));
+		alloc_tag_sub(&chunk->obj_exts[off >> PCPU_MIN_ALLOC_SHIFT].tag, size);
 }
 #else
 static void pcpu_alloc_tag_alloc_hook(struct pcpu_chunk *chunk, int off,
@@ -1744,7 +1741,7 @@ void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
 	int slot, off, cpu, ret;
 	unsigned long flags;
 	void __percpu *ptr;
-	size_t bits, bit_align;
+	size_t bits, bit_align, full_size;
 
 	gfp = current_gfp_context(gfp);
 	/*
@@ -1773,6 +1770,7 @@ void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
 	size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
 	bits = size >> PCPU_MIN_ALLOC_SHIFT;
 	bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
+	full_size = pcpu_obj_full_size(size);
 
 	if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
 		     !is_power_of_2(align))) {
@@ -1781,7 +1779,7 @@ void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
 		return NULL;
 	}
 
-	if (unlikely(!pcpu_memcg_pre_alloc_hook(size, gfp, &objcg)))
+	if (unlikely(!pcpu_memcg_pre_alloc_hook(full_size, gfp, &objcg)))
 		return NULL;
 
 	if (!is_atomic) {
@@ -1793,7 +1791,7 @@ void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
 		if (gfp & __GFP_NOFAIL) {
 			mutex_lock(&pcpu_alloc_mutex);
 		} else if (mutex_lock_killable(&pcpu_alloc_mutex)) {
-			pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
+			pcpu_memcg_post_alloc_hook(objcg, NULL, 0, full_size);
 			return NULL;
 		}
 	}
@@ -1903,12 +1901,11 @@ void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
 	kmemleak_alloc_percpu(ptr, size, gfp);
 
 	trace_percpu_alloc_percpu(_RET_IP_, reserved, is_atomic, size, align,
-				  chunk->base_addr, off, ptr,
-				  pcpu_obj_full_size(size), gfp);
+				  chunk->base_addr, off, ptr, full_size, gfp);
 
-	pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);
+	pcpu_memcg_post_alloc_hook(objcg, chunk, off, full_size);
 
-	pcpu_alloc_tag_alloc_hook(chunk, off, size);
+	pcpu_alloc_tag_alloc_hook(chunk, off, full_size);
 
 	return ptr;
 
@@ -1938,7 +1935,7 @@ void __percpu *pcpu_alloc_noprof(size_t size, size_t align, bool reserved,
 		mutex_unlock(&pcpu_alloc_mutex);
 	}
 
-	pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
+	pcpu_memcg_post_alloc_hook(objcg, NULL, 0, full_size);
 
 	return NULL;
 }
@@ -2242,6 +2239,7 @@ void free_percpu(void __percpu *ptr)
 	struct pcpu_chunk *chunk;
 	unsigned long flags;
 	int size, off;
+	size_t full_size;
 	bool need_balance = false;
 
 	if (!ptr)
@@ -2262,10 +2260,11 @@ void free_percpu(void __percpu *ptr)
 		WARN_ON_ONCE(1);
 		return;
 	}
+	full_size = pcpu_obj_full_size(size);
 
-	pcpu_alloc_tag_free_hook(chunk, off, size);
+	pcpu_alloc_tag_free_hook(chunk, off, full_size);
 
-	pcpu_memcg_free_hook(chunk, off, size);
+	pcpu_memcg_free_hook(chunk, off, full_size);
 
 	/*
 	 * If there are more than one fully free chunks, wake up grim reaper.

base-commit: 2887e63d2e8e0cf55402612d8996ce955a2c3e55
-- 
2.53.0-Meta