Hello. On 02/02/2015 05:02 PM, Jiri Slaby wrote:
From: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> Subject: [PATCH] pci-dma: Fix x86 dma_alloc_coherent to fully clear all pages returned
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.
Other drivers may have similar issue if it assumes that the pages allocated are completely zeroed.
This patch ensures that the pages returned are fully cleared.
Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # 3.16+
--- arch/x86/kernel/pci-dma.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index a25e202..e9d8dee 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -125,6 +125,8 @@ again: return NULL; } + /* round up to full page size */ + size = (size + ~PAGE_MASK) & PAGE_MASK;
Hi, is this an open-coded version of PAGE_ALIGN?
Yes, it appears so. :-) WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
