linux-kernel - Re: [PATCH] drivers: base: dma-mapping: page align the size when unmap_kernel

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Date:	Mon, 8 Aug 2016 12:29:08 +0800
From:	Peng Fan <van.freenix@...il.com>
To:	gregkh@...uxfoundation.org
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] drivers: base: dma-mapping: page align the size when
 unmap_kernel_range

Hi,

Kindly ping.. since more than two weeks from patch sent out.

Thanks,
Peng.
On Thu, Jul 21, 2016 at 04:04:21PM +0800, Peng Fan wrote:
>When dma_common_free_remap, the input parameter 'size' may not
>be page aligned. And, met kernel warning when doing iommu dma
>for usb on i.MX8 platform:
>"
>WARNING: CPU: 0 PID: 869 at mm/vmalloc.c:70 vunmap_page_range+0x1cc/0x1d0()
>Modules linked in:
>CPU: 0 PID: 869 Comm: kworker/u8:2 Not tainted 4.1.12-00444-gc5f9d1d-dirty #147
>Hardware name: Freescale i.MX8DV Sabreauto (DT)
>Workqueue: ci_otg ci_otg_work
>Call trace:
>[<ffffffc000089920>] dump_backtrace+0x0/0x124
>[<ffffffc000089a54>] show_stack+0x10/0x1c
>[<ffffffc0006d1e6c>] dump_stack+0x84/0xc8
>[<ffffffc0000b4568>] warn_slowpath_common+0x98/0xd0
>[<ffffffc0000b4664>] warn_slowpath_null+0x14/0x20
>[<ffffffc000170348>] vunmap_page_range+0x1c8/0x1d0
>[<ffffffc000170388>] unmap_kernel_range+0x20/0x88
>[<ffffffc000460ad0>] dma_common_free_remap+0x74/0x84
>[<ffffffc0000940d8>] __iommu_free_attrs+0x9c/0x178
>[<ffffffc0005032bc>] ehci_mem_cleanup+0x140/0x194
>[<ffffffc000503548>] ehci_stop+0x8c/0xdc
>[<ffffffc0004e8258>] usb_remove_hcd+0xf0/0x1cc
>[<ffffffc000516bc0>] host_stop+0x1c/0x58
>[<ffffffc000514240>] ci_otg_work+0xdc/0x120
>[<ffffffc0000c9c34>] process_one_work+0x134/0x33c
>[<ffffffc0000c9f78>] worker_thread+0x13c/0x47c
>[<ffffffc0000cf43c>] kthread+0xd8/0xf0
>"
>
>For dma_common_pages_remap:
>dma_common_pages_remap
>   |->get_vm_area_caller
>        |->__get_vm_area_node
>            |->size = PAGE_ALIGN(size);   Round up to page aligned
>
>So, in dma_common_free_remap, we also need a page aligned size,
>pass 'PAGE_ALIGN(size)' to unmap_kernel_range.
>
>Signed-off-by: Peng Fan <van.freenix@...il.com>
>Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>Cc: <stable@...r.kernel.org>
>---
> drivers/base/dma-mapping.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
>index d799662..261420d 100644
>--- a/drivers/base/dma-mapping.c
>+++ b/drivers/base/dma-mapping.c
>@@ -334,7 +334,7 @@ void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
> 		return;
> 	}
> 
>-	unmap_kernel_range((unsigned long)cpu_addr, size);
>+	unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
> 	vunmap(cpu_addr);
> }
> #endif
>-- 
>2.6.2
>