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From:   Vlastimil Babka <vbabka@suse.cz>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mel Gorman <mgorman@techsingularity.net>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Jann Horn <jannh@google.com>, Vlastimil Babka <vbabka@suse.cz>
Subject: [RFC 02/26] mm, slub: allocate private object map for validate_slab_cache()
Date:   Tue, 25 May 2021 01:39:22 +0200
Message-Id: <20210524233946.20352-3-vbabka@suse.cz>
In-Reply-To: <20210524233946.20352-1-vbabka@suse.cz>
References: <20210524233946.20352-1-vbabka@suse.cz>
MIME-Version: 1.0
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Precedence: bulk

validate_slab_cache() is called either to handle a sysfs write, or from a
self-test context. In both situations it's straightforward to preallocate a
private object bitmap instead of grabbing the shared static one meant for
critical sections, so let's do that.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/slub.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 4c876749f322..ed0f2620b19b 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4622,7 +4622,8 @@ static int count_total(struct page *page)
 #endif
 
 #ifdef CONFIG_SLUB_DEBUG
-static void validate_slab(struct kmem_cache *s, struct page *page)
+static void validate_slab(struct kmem_cache *s, struct page *page,
+			  unsigned long *obj_map)
 {
 	void *p;
 	void *addr = page_address(page);
@@ -4634,7 +4635,7 @@ static void validate_slab(struct kmem_cache *s, struct page *page)
 		goto unlock;
 
 	/* Now we know that a valid freelist exists */
-	map = get_map(s, page);
+	__fill_map(obj_map, s, page);
 	for_each_object(p, s, addr, page->objects) {
 		u8 val = test_bit(__obj_to_index(s, addr, p), map) ?
 			 SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
@@ -4642,13 +4643,12 @@ static void validate_slab(struct kmem_cache *s, struct page *page)
 		if (!check_object(s, page, p, val))
 			break;
 	}
-	put_map(map);
 unlock:
 	slab_unlock(page);
 }
 
 static int validate_slab_node(struct kmem_cache *s,
-		struct kmem_cache_node *n)
+		struct kmem_cache_node *n, unsigned long *obj_map)
 {
 	unsigned long count = 0;
 	struct page *page;
@@ -4657,7 +4657,7 @@ static int validate_slab_node(struct kmem_cache *s,
 	spin_lock_irqsave(&n->list_lock, flags);
 
 	list_for_each_entry(page, &n->partial, slab_list) {
-		validate_slab(s, page);
+		validate_slab(s, page, obj_map);
 		count++;
 	}
 	if (count != n->nr_partial)
@@ -4668,7 +4668,7 @@ static int validate_slab_node(struct kmem_cache *s,
 		goto out;
 
 	list_for_each_entry(page, &n->full, slab_list) {
-		validate_slab(s, page);
+		validate_slab(s, page, obj_map);
 		count++;
 	}
 	if (count != atomic_long_read(&n->nr_slabs))
@@ -4685,10 +4685,17 @@ static long validate_slab_cache(struct kmem_cache *s)
 	int node;
 	unsigned long count = 0;
 	struct kmem_cache_node *n;
+	unsigned long *obj_map;
+
+	obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
+	if (!obj_map)
+		return -ENOMEM;
 
 	flush_all(s);
 	for_each_kmem_cache_node(s, node, n)
-		count += validate_slab_node(s, n);
+		count += validate_slab_node(s, n, obj_map);
+
+	bitmap_free(obj_map);
 
 	return count;
 }
-- 
2.31.1