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

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Date:	Thu, 21 Jul 2016 16:04:21 +0800
From:	Peng Fan <van.freenix@...il.com>
To:	gregkh@...uxfoundation.org
Cc:	linux-kernel@...r.kernel.org, van.freenix@...il.com,
	stable@...r.kernel.org
Subject: [PATCH] drivers: base: dma-mapping: page align the size when unmap_kernel_range

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