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

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

[Jason Wang]

On 07/15/2013 01:38 PM, K. Y. Srinivasan wrote:
> 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@microsoft.com>
> Cc: Stable <stable@vger.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);
>  
>  	}
>  

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks

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

[K. Y. Srinivasan]

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@microsoft.com>
Cc: Stable <stable@vger.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

[PATCH V2 2/2] Drivers: hv: balloon: Do not post pressure status if interrupted

[K. Y. Srinivasan]

When we are posting pressure status, we may get interrupted and handle
the un-balloon operation. In this case just don't post the status as we
know the pressure status is stale.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Stable <stable@vger.kernel.org>
---
 drivers/hv/hv_balloon.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 61b7351..deb5c25 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -975,6 +975,14 @@ static void post_status(struct hv_dynmem_device *dm)
 				dm->num_pages_ballooned +
 				compute_balloon_floor();
 
+	/*
+	 * If our transaction ID is no longer current, just don't
+	 * send the status. This can happen if we were interrupted
+	 * after we picked our transaction ID.
+	 */
+	if (status.hdr.trans_id != atomic_read(&trans_id))
+		return;
+
 	vmbus_sendpacket(dm->dev->channel, &status,
 				sizeof(struct dm_status),
 				(unsigned long)NULL,
-- 
1.7.4.1