linux-kernel - [PATCH 3/3] mm/vmalloc: move VM_UNINITIALIZED just before show_numa

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Message-Id: <1378125345-13228-3-git-send-email-liwanp@linux.vnet.ibm.com>
Date:	Mon,  2 Sep 2013 20:35:45 +0800
From:	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Joonsoo Kim <iamjoonsoo.kim@....com>,
	David Rientjes <rientjes@...gle.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>
Subject: [PATCH 3/3] mm/vmalloc: move VM_UNINITIALIZED just before show_numa_info

The VM_UNINITIALIZED/VM_UNLIST flag introduced by commit f5252e00(mm: avoid 
null pointer access in vm_struct via /proc/vmallocinfo) is used to avoid 
accessing the pages field with unallocated page when show_numa_info() is 
called. This patch move the check just before show_numa_info in order that 
some messages still can be dumped via /proc/vmallocinfo.

Signed-off-by: Wanpeng Li <liwanp@...ux.vnet.ibm.com>
---
 mm/vmalloc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e3ec8b4..c4720cd 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2590,11 +2590,6 @@ static int s_show(struct seq_file *m, void *p)
 
 	v = va->vm;
 
-	/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
-	smp_rmb();
-	if (v->flags & VM_UNINITIALIZED)
-		return 0;
-
 	seq_printf(m, "0x%pK-0x%pK %7ld",
 		v->addr, v->addr + v->size, v->size);
 
@@ -2622,6 +2617,11 @@ static int s_show(struct seq_file *m, void *p)
 	if (v->flags & VM_VPAGES)
 		seq_printf(m, " vpages");
 
+	/* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
+	smp_rmb();
+	if (v->flags & VM_UNINITIALIZED)
+		return;
+
 	show_numa_info(m, v);
 	seq_putc(m, '\n');
 	return 0;
-- 
1.8.1.2

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