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From:   paulmck@kernel.org
To:     rcu@vger.kernel.org
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        andrii@kernel.org, "Paul E. McKenney" <paulmck@kernel.org>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>, linux-mm@kvack.org
Subject: [PATCH v2 sl-b 2/5] mm: Make mem_dump_obj() handle NULL and zero-sized pointers
Date:   Tue,  8 Dec 2020 17:13:00 -0800
Message-Id: <20201209011303.32737-2-paulmck@kernel.org>
In-Reply-To: <20201209011124.GA31164@paulmck-ThinkPad-P72>
References: <20201209011124.GA31164@paulmck-ThinkPad-P72>
Precedence: bulk

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit makes mem_dump_obj() call out NULL and zero-sized pointers
specially instead of classifying them as non-paged memory.

Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <linux-mm@kvack.org>
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 mm/util.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/util.c b/mm/util.c
index d0e60d2..8c2449f 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -985,7 +985,12 @@ int __weak memcmp_pages(struct page *page1, struct page *page2)
 void mem_dump_obj(void *object)
 {
 	if (!virt_addr_valid(object)) {
-		pr_cont(" non-paged (local) memory.\n");
+		if (object == NULL)
+			pr_cont(" NULL pointer.\n");
+		else if (object == ZERO_SIZE_PTR)
+			pr_cont(" zero-size pointer.\n");
+		else
+			pr_cont(" non-paged (local) memory.\n");
 		return;
 	}
 	if (kmem_valid_obj(object)) {
-- 
2.9.5