This patch appears to have gotten lost in the shuffle but still seems relevant. I found it while auditing dm-devel's patchwork, patch is here: https://patchwork.kernel.org/patch/71073/ On Tue, Jan 05 2010 at 12:20pm -0500, Moger, Babu <Babu.Moger@xxxxxxx> wrote: > 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; > > > > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
