From: Minchan Kim <minchan@kernel.org>
Date: Fri, 28 Sep 2012 00:19:58 +0000 (+1000)
Subject: mm: enhance comment and bug check
X-Git-Tag: next-20121004~1^2~206
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=3c8d0e15d14cc51dfa8e7a0500a934343d0101d4;p=karo-tx-linux.git

mm: enhance comment and bug check

This patch updates comment and bug check.
It can be fold into [1].

[1] mm-revert-0def08e3-mm-mempolicyc-check-return-code-of-check_range.patch

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vasiliy Kulikov <segooon@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 7177da24b3fa..7c72c359f843 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -988,9 +988,11 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
 	node_set(source, nmask);
 
 	/*
-	 * Collect migrate pages and it shoudn't be failed.
+	 * This does not "check" the range but isolates all pages that
+	 * need migration.  Between passing in the full user address
+	 * space range and MPOL_MF_DISCONTIG_OK, this call can not fail.
 	 */
-	VM_BUG_ON(flags & MPOL_MF_STRICT);
+	VM_BUG_ON(!(flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)));
 	check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
 			flags | MPOL_MF_DISCONTIG_OK, &pagelist);