linux-kernel - [PATCH 1/2] mm/memblock: add more comments in code

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Date:	Wed, 11 Dec 2013 17:36:13 +0200
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	<santosh.shilimkar@...com>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Yinghai Lu <yinghai@...nel.org>, Tejun Heo <tj@...nel.org>
Subject: [PATCH 1/2] mm/memblock: add more comments in code

Add additional description on:
- why warning is produced in case if slab is ready
- why kmemleak_alloc is called for each allocated memory block

Cc: Yinghai Lu <yinghai@...nel.org>
Cc: Tejun Heo <tj@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---

It's additional change on top of the memblock series 
https://lkml.org/lkml/2013/12/9/715

 mm/memblock.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index d03d50a..974f0d3 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -985,6 +985,11 @@ static void * __init memblock_virt_alloc_internal(
 		pr_warn("%s: usage of MAX_NUMNODES is depricated. Use NUMA_NO_NODE\n",
 			__func__);
 
+	/*
+	 * Detect any accidental use of these APIs after slab is ready, as at
+	 * this moment memblock may be deinitialized already and its
+	 * internal data may be destroyed (after execution of free_all_bootmem)
+	 */
 	if (WARN_ON_ONCE(slab_is_available()))
 		return kzalloc_node(size, GFP_NOWAIT, nid);
 
@@ -1021,7 +1026,9 @@ done:
 
 	/*
 	 * The min_count is set to 0 so that bootmem allocated blocks
-	 * are never reported as leaks.
+	 * are never reported as leaks. This is because many of these blocks
+	 * are only referred via the physical address which is not
+	 * looked up by kmemleak.
 	 */
 	kmemleak_alloc(ptr, size, 0, 0);
 
-- 
1.7.9.5

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