Hello, > -----Original Message----- > From: Guenter Roeck <groe...@gmail.com> On Behalf Of Guenter Roeck > Sent: Thursday, June 13, 2019 9:06 PM > > On 6/13/19 8:34 AM, Fredrik Noring wrote: > > Hi Guenter, > > > >> Thanks for the confirmation. Do you see the problem only with the > >> ohci-sm501 driver or also with others ? > > > > All are likely affected, but it depends, because I believe the problem > is > > that the USB subsystem runs out of memory. Please try the attached patch! > > > > The pool assumed 4096 byte page alignment for every allocation, which is > > excessive given that many requests are for 16 and 32 bytes. In the patch > > below, I have turned down the order to 5, which is good enough for the > ED > > and TD structures of the OHCI, but not enough for the HCCA that needs > 256 > > byte alignment. With some luck, the WARN_ON_ONCE will not trigger in > your > > test, though. If it does, you may try to increase the order from 5 to 8. > > > > You are right, the patch below fixes the problem. I did not get the > warning > with order==5. Nevertheless, I also tested with order==8; that works as > well.
Sorry for the late reply, I was OOO for past week+ and many thanks for taking a look at this. So if my understanding is correct, an order of PAGE_SHIFT is too large and leads to waste of memory and in the end to an out of memory condition. This leaves me wondering what a safe order value would be. I'll try to look into the legacy dma coherent allocation code maybe I can gather some info on the subject. --- Best Regards, Laurentiu > > > I have observed strange things happen when the USB subsystem runs out of > > memory. The mass storage drivers often seem to busy-wait on -ENOMEM, > > consuming a lot of processor resources. It would be much more efficient > > to sleep waiting for memory to become available. > > > > In your case I suspect that allocation failures are not correctly > > attributed. Certain kinds of temporary freezes may also occur, as the > > various devices are reset due to host memory allocation errors. > > > Fredrik > > > > diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > > --- a/drivers/usb/core/hcd.c > > +++ b/drivers/usb/core/hcd.c > > @@ -3011,7 +3011,7 @@ int usb_hcd_setup_local_mem(struct usb_hcd *hcd, > phys_addr_t phys_addr, > > int err; > > void __iomem *local_mem; > > > > - hcd->localmem_pool = devm_gen_pool_create(hcd->self.sysdev, > PAGE_SHIFT, > > + hcd->localmem_pool = devm_gen_pool_create(hcd->self.sysdev, 5, > > dev_to_node(hcd->self.sysdev), > > dev_name(hcd->self.sysdev)); > > if (IS_ERR(hcd->localmem_pool)) > > diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c > > --- a/drivers/usb/host/ohci-hcd.c > > +++ b/drivers/usb/host/ohci-hcd.c > > @@ -517,6 +517,7 @@ static int ohci_init (struct ohci_hcd *ohci) > > GFP_KERNEL); > > if (!ohci->hcca) > > return -ENOMEM; > > + WARN_ON_ONCE(ohci->hcca_dma & 0xff); > > > > if ((ret = ohci_mem_init (ohci)) < 0) > > ohci_stop (hcd); > >
