From:   Bixuan Cui <cuibixuan@linux.alibaba.com>
To:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        torvalds@linux-foundation.org
Cc:     leon@kernel.org, cuibixuan@linux.alibaba.com,
        akpm@linux-foundation.org, w@1wt.eu, keescook@chromium.org
Subject: [PATCH -next] mm: delete oversized WARN_ON() in kvmalloc() calls
Date:   Thu,  2 Dec 2021 10:06:24 +0800
Message-Id: <1638410784-48646-1-git-send-email-cuibixuan@linux.alibaba.com>
Precedence: bulk

Delete the WARN_ON() and return NULL directly for oversized parameter
in kvmalloc() calls.
Also add unlikely().

Fixes: 7661809d493b ("mm: don't allow oversized kvmalloc() calls")
Signed-off-by: Bixuan Cui <cuibixuan@linux.alibaba.com>
---
There are a lot of oversize warnings and patches about kvmalloc() calls
recently. Maybe these warnings are not very necessary.

https://lore.kernel.org/all/YadOjJXMTjP85MQx@unreal

The example of size check in __do_kmalloc_node():
__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
{
        struct kmem_cache *cachep;
        void *ret;

        if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
                return NULL;
        cachep = kmalloc_slab(size, flags);

 mm/util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/util.c b/mm/util.c
index 7e433690..d26f19c 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -587,7 +587,7 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
 		return ret;
 
 	/* Don't even allow crazy sizes */
-	if (WARN_ON_ONCE(size > INT_MAX))
+	if (unlikely(size > INT_MAX))
 		return NULL;
 
 	return __vmalloc_node(size, 1, flags, node,
-- 
1.8.3.1