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Date: Thu, 19 Feb 2015 08:56:42 -0800 From: Tim Chen <tim.c.chen@...ux.intel.com> To: Mathias Nyman <mathias.nyman@...ux.intel.com> Cc: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jslaby@...e.cz>, "H. Peter Anvin" <hpa@...or.com>, Akinobu Mita <akinobu.mita@...il.com>, Ingo Molnar <mingo@...e.hu>, Andrew Morton <akpm@...ux-foundation.org>, Marek Szyprowski <m.szyprowski@...sung.com>, Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org, x86@...nel.org, linux-usb@...r.kernel.org, stable <stable@...r.kernel.org>, Alan Stern <stern@...land.harvard.edu>, ak <ak@...ux.intel.com> Subject: Re: [PATCH] xhci: use dma_alloc_coherent with fully cleared pages On Thu, 2015-02-19 at 17:05 +0200, Mathias Nyman wrote: > On 19.02.2015 02:34, Tim Chen wrote: > > > > Commit d92ef66c4f8f ("x86: make dma_alloc_coherent() return zeroed memory > > if CMA is enabled") changed the dma_alloc_coherent page clearance from > > using an __GFP_ZERO in page allocation to not setting the flag but doing > > an explicit memory clear at the end. > > > > However the memory clear only covered the memory size that > > was requested, but may not be up to the full extent of the > > last page, if the total pages returned exceed the > > memory size requested. This behavior has caused problem with XHCI > > and caused it to hang: > > > > kernel: xhci_hcd 0000:00:14.0: Stopped the command ring failed, maybe the host is dead > > kernel: xhci_hcd 0000:00:14.0: Abort command ring failed > > kernel: xhci_hcd 0000:00:14.0: HC died; cleaning up > > kernel: xhci_hcd 0000:00:14.0: Error while assigning device slot ID > > kernel: xhci_hcd 0000:00:14.0: Max number of devices this xHCI host supports is 64. > > > > This patch reverts xhci the use the old behavior to avoid the hang. XHCI should > > do a proper fix to avoid this un-allocated memory. > > > > Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com> > > Cc: <stable@...r.kernel.org> # 3.16+ > > --- > > drivers/usb/host/xhci-mem.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c > > index 5cb3d7a..39e7196 100644 > > --- a/drivers/usb/host/xhci-mem.c > > +++ b/drivers/usb/host/xhci-mem.c > > @@ -1658,7 +1658,7 @@ static int scratchpad_alloc(struct xhci_hcd *xhci, gfp_t flags) > > goto fail_sp; > > > > xhci->scratchpad->sp_array = dma_alloc_coherent(dev, > > - num_sp * sizeof(u64), > > + PAGE_ALIGN(num_sp * sizeof(u64)), > > &xhci->scratchpad->sp_dma, flags); > > if (!xhci->scratchpad->sp_array) > > goto fail_sp2; > > > > Thanks for figuring out that the issue was in allocation of scratchpad memory. > > Turns out we don't calculate the num_sp correctly in the first place, we didn't include > the additional high order field of the max scratchpad buffers xhci tells we should reserve. > I got a patch for this and will send it to forward to Greg once 3.20-rc1 is tagged > > -Mathias Great. Thanks for fixing this. Tim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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