This patch changes the memory allocation flag from GFP_KERNEL to GFP_NOIO which is more appropriate.
This was noticed by Mike Christie and Rob Evers..
Mike Christie wrote:
> Rob Evers wrote:
>> +
>> +static int queue_mode_select(struct scsi_device *sdev,
>> + activate_complete fn, void *data)
>> +{
>> + struct rdac_queue_data *qdata;
>> + struct rdac_controller *ctlr;
>> +
>> + qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
>> + if (!qdata)
>> + return SCSI_DH_RETRY;
>> +
>
> It looks like this is called in the main IO path. A failed IO could cause, the path to go down,
> then we would call this to active a new path. If the system needed to write out pages to the same
> disk that just had the failed path so it can allocate memory then GFP_KERNEL would be bad to use here.
> You would use a mempool and still use something like GFP_NOIO. If a mempool is not possible for some
> reason, then you would want to still use GFP_NOIO.
Using mempool would become bit more complex here because I cannot assume about the number of elements
during the allocation. I would use GFP_NOIO.
CC: Mike Christie <michaelc@xxxxxxxxxxx>
CC: Rob Evers <revers@xxxxxxxxxx>
CC: Chandra Seetharaman <chandra.seetharaman@xxxxxxxxxx>
Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
---
--- linux-2.6.33-rc2/drivers/scsi/device_handler/scsi_dh_rdac.c.orig 2010-01-05 11:49:22.000000000 -0400
+++ linux-2.6.33-rc2/drivers/scsi/device_handler/scsi_dh_rdac.c 2010-01-05 11:53:13.000000000 -0400
@@ -624,7 +624,7 @@ static int queue_mode_select(struct scsi
struct rdac_queue_data *qdata;
struct rdac_controller *ctlr;
- qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
+ qdata = kzalloc(sizeof(*qdata), GFP_NOIO);
if (!qdata)
return SCSI_DH_RETRY;
--
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