linux-kernel - [PATCH V2 1/2] Drivers: hv: balloon: Fix a bug in the hot-add code

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Message-Id: <1373866692-9353-1-git-send-email-kys@microsoft.com>
Date:	Sun, 14 Jul 2013 22:38:11 -0700
From:	"K. Y. Srinivasan" <kys@...rosoft.com>
To:	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
	jasowang@...hat.com
Cc:	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Stable <stable@...r.kernel.org>
Subject: [PATCH V2 1/2] Drivers: hv: balloon: Fix a bug in the hot-add code

As we hot-add 128 MB chunks of memory, we wait to ensure that the memory
is onlined before attempting to hot-add the next chunk. If the udev rule for
memory hot-add is not executed within the allowed time, we would rollback the
state and abort further hot-add. Since the hot-add has succeeded and the only
failure is that the memory is not onlined within the allowed time, we should not
be rolling back the state. Fix this bug.

Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
Cc: Stable <stable@...r.kernel.org>
---
 drivers/hv/hv_balloon.c |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 4c605c7..61b7351 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -562,7 +562,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
 				struct hv_hotadd_state *has)
 {
 	int ret = 0;
-	int i, nid, t;
+	int i, nid;
 	unsigned long start_pfn;
 	unsigned long processed_pfn;
 	unsigned long total_pfn = pfn_count;
@@ -607,14 +607,11 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
 
 		/*
 		 * Wait for the memory block to be onlined.
+		 * Since the hot add has succeeded, it is ok to
+		 * proceed even if the pages in the hot added region
+		 * have not been "onlined" within the allowed time.
 		 */
-		t = wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
-		if (t == 0) {
-			pr_info("hot_add memory timedout\n");
-			has->ha_end_pfn -= HA_CHUNK;
-			has->covered_end_pfn -=  processed_pfn;
-			break;
-		}
+		wait_for_completion_timeout(&dm_device.ol_waitevent, 5*HZ);
 
 	}
 
-- 
1.7.4.1

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