linux-kernel - [PATCH 3/5] mm/slab: Do not call kmalloc

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Date:   Mon, 21 Feb 2022 10:53:34 +0000
From:   Hyeonggon Yoo <42.hyeyoo@...il.com>
To:     linux-mm@...ck.org
Cc:     Roman Gushchin <guro@...com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        David Rientjes <rientjes@...gle.com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>
Subject: [PATCH 3/5] mm/slab: Do not call kmalloc_large() for unsupported size

SLAB's kfree() does not support freeing an object that is allocated from
kmalloc_large(). Fix this as SLAB do not pass requests larger than
KMALLOC_MAX_CACHE_SIZE directly to page allocator.

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@...il.com>
---
 include/linux/slab.h | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 37bde99b74af..aeda3e863f2b 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -564,15 +564,19 @@ static __always_inline __alloc_size(1) void *kmalloc_large(size_t size, gfp_t fl
  *	Try really hard to succeed the allocation but fail
  *	eventually.
  */
+#ifndef CONFIG_SLOB
 static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
 {
 	if (__builtin_constant_p(size)) {
-#ifndef CONFIG_SLOB
 		unsigned int index;
-#endif
-		if (size > KMALLOC_MAX_CACHE_SIZE)
-			return kmalloc_large(size, flags);
-#ifndef CONFIG_SLOB
+
+		if (size > KMALLOC_MAX_CACHE_SIZE) {
+			if (IS_ENABLED(CONFIG_SLUB))
+				return kmalloc_large(size, flags);
+			else
+				return NULL;
+		}
+
 		index = kmalloc_index(size);
 
 		if (!index)
@@ -581,10 +585,17 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
 		return kmem_cache_alloc_trace(
 				kmalloc_caches[kmalloc_type(flags)][index],
 				flags, size);
-#endif
 	}
 	return __kmalloc(size, flags);
 }
+#else
+static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
+{
+	if (__builtin_constant_p(size) && size > KMALLOC_MAX_CACHE_SIZE)
+		return kmalloc_large(size, flags);
+	return __kmalloc(size, flags);
+}
+#endif
 
 static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t flags, int node)
 {
-- 
2.33.1