linux-kernel - [PATCH] mm/slab: Add a __GFP_ACCOUNT GFP flag check for slab allocation

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Message-Id: <20200614063858.85118-1-songmuchun@bytedance.com>
Date:   Sun, 14 Jun 2020 14:38:58 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH] mm/slab: Add a __GFP_ACCOUNT GFP flag check for slab allocation

When a kmem_cache is initialized with SLAB_ACCOUNT slab flag, we must
not call kmem_cache_alloc with __GFP_ACCOUNT GFP flag. In this case,
we can be accounted to kmemcg twice. This is not correct. So we add a
__GFP_ACCOUNT GFP flag check for slab allocation.

We also introduce a new helper named fixup_gfp_flags to do that check.
We can reuse the fixup_gfp_flags for SLAB/SLUB.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
 mm/slab.c | 10 +---------
 mm/slab.h | 21 +++++++++++++++++++++
 mm/slub.c | 10 +---------
 3 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 9350062ffc1a..6e0110bef2d6 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -126,8 +126,6 @@
 
 #include <trace/events/kmem.h>
 
-#include	"internal.h"
-
 #include	"slab.h"
 
 /*
@@ -2579,13 +2577,7 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep,
 	 * Be lazy and only check for valid flags here,  keeping it out of the
 	 * critical path in kmem_cache_alloc().
 	 */
-	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
-		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
-		flags &= ~GFP_SLAB_BUG_MASK;
-		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
-				invalid_mask, &invalid_mask, flags, &flags);
-		dump_stack();
-	}
+	flags = fixup_gfp_flags(cachep, flags);
 	WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
 	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
diff --git a/mm/slab.h b/mm/slab.h
index 815e4e9a94cd..0b91f2a7b033 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -109,6 +109,7 @@ struct memcg_cache_params {
 #include <linux/kmemleak.h>
 #include <linux/random.h>
 #include <linux/sched/mm.h>
+#include "internal.h"
 
 /*
  * State of the slab allocator.
@@ -627,6 +628,26 @@ struct kmem_cache_node {
 
 };
 
+static inline gfp_t fixup_gfp_flags(struct kmem_cache *s, gfp_t flags)
+{
+	gfp_t invalid_mask = 0;
+
+	if (unlikely(flags & GFP_SLAB_BUG_MASK))
+		invalid_mask |= flags & GFP_SLAB_BUG_MASK;
+
+	if (unlikely(flags & __GFP_ACCOUNT && s->flags & SLAB_ACCOUNT))
+		invalid_mask |= __GFP_ACCOUNT;
+
+	if (unlikely(invalid_mask)) {
+		flags &= ~invalid_mask;
+		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
+				invalid_mask, &invalid_mask, flags, &flags);
+		dump_stack();
+	}
+
+	return flags;
+}
+
 static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
 {
 	return s->node[node];
diff --git a/mm/slub.c b/mm/slub.c
index b8f798b50d44..49b5cb7da318 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -37,8 +37,6 @@
 
 #include <trace/events/kmem.h>
 
-#include "internal.h"
-
 /*
  * Lock order:
  *   1. slab_mutex (Global Mutex)
@@ -1745,13 +1743,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 {
-	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
-		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
-		flags &= ~GFP_SLAB_BUG_MASK;
-		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
-				invalid_mask, &invalid_mask, flags, &flags);
-		dump_stack();
-	}
+	flags = fixup_gfp_flags(s, flags);
 
 	return allocate_slab(s,
 		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
-- 
2.11.0