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From: paulmck@kernel.org
To: linux-kernel@vger.kernel.org, rcu@vger.kernel.org, linux-mm@kvack.org
Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com,
	iamjoonsoo.kim@lge.com, akpm@linux-foundation.org,
	ming.lei@redhat.com, axboe@kernel.dk, kernel-team@fb.com,
	"Paul E. McKenney" <paulmck@kernel.org>
Subject: [PATCH mm,percpu_ref,rcu 2/6] mm: Make mem_dump_obj() handle NULL and zero-sized pointers
Date: Tue,  5 Jan 2021 17:17:46 -0800
Message-ID: <20210106011750.13709-2-paulmck@kernel.org> (raw)
In-Reply-To: <20210106011603.GA13180@paulmck-ThinkPad-P72>

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>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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 da46f9d..92f23d2 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -997,7 +997,12 @@ 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


  parent reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-06  1:16 [PATCH v4 sl-b 0/6] Export return addresses etc. for better diagnostics Paul E. McKenney
2021-01-06  1:17 ` [PATCH mm,percpu_ref,rcu 1/6] mm: Add mem_dump_obj() to print source of memory block paulmck
2021-01-08 13:50   ` Vlastimil Babka
2021-01-08 19:01     ` Paul E. McKenney
2021-01-08 19:41       ` Vlastimil Babka
2021-01-06  1:17 ` paulmck [this message]
2021-01-06  1:17 ` [PATCH mm,percpu_ref,rcu 3/6] mm: Make mem_dump_obj() handle vmalloc() memory paulmck
2021-01-08 15:30   ` Vlastimil Babka
2021-01-06  1:17 ` [PATCH mm,percpu_ref,rcu 4/6] mm: Make mem_obj_dump() vmalloc() dumps include start and length paulmck
2021-01-08 15:30   ` Vlastimil Babka
2021-01-06  1:17 ` [PATCH mm,percpu_ref,rcu 5/6] rcu: Make call_rcu() print mem_dump_obj() info for double-freed callback paulmck
2021-01-06  1:17 ` [PATCH mm,percpu_ref,rcu 6/6] percpu_ref: Dump mem_dump_obj() info upon reference-count underflow paulmck
2021-01-06 21:48 ` [PATCH v4 sl-b 0/6] Export return addresses etc. for better diagnostics Andrew Morton
2021-01-06 23:42   ` Paul E. McKenney
2021-01-08  0:26     ` Paul E. McKenney
2021-01-08 15:35       ` Vlastimil Babka
2021-01-08 17:36         ` Paul E. McKenney

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