> -----Original Message----- > From: Mike Snitzer [mailto:snitzer@xxxxxxxxxx] > Sent: Thursday, November 04, 2010 10:15 AM > To: device-mapper development > Cc: linux-scsi@xxxxxxxxxxxxxxx; Chandra Seetharaman; > michaelc@xxxxxxxxxxx; Rob Evers; Moger, Babu > Subject: Re: scsi_dh_rdac: Changing the memory allocation flag from > GFP_KERNEL to GFP_NOIO > > 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/ Yes, Please.. We need this patch.. > > 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
