[PATCH] [PATCH 4.9] staging: android: ion: fix page is NULL

[Cheng Chao]

kernel panic is here:

Unable to handle kernel paging request at virtual address b0380000
pgd = d9d94000
[b0380000] *pgd=00000000
Internal error: Oops: 2805 [#1] PREEMPT SMP ARM
...
task: daa2dd00 task.stack: da194000
PC is at v7_dma_clean_range+0x1c/0x34
LR is at arm_dma_sync_single_for_device+0x44/0x58
pc : [<c011aa0c>]    lr : [<c011645c>]    psr: 200f0013
sp : da195da0  ip : dc1f9000  fp : c1043dc4
r10: 00000000  r9 : c16f1f58  r8 : 00000001
r7 : c1621f94  r6 : c0116418  r5 : 00000000  r4 : c011aa58
r3 : 0000003f  r2 : 00000040  r1 : b0480000  r0 : b0380000
Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c5383d  Table: 19d9406a  DAC: 00000051
...
[<c011aa0c>] (v7_dma_clean_range) from [<c011645c>] (arm_dma_sync_single_for_device+0x44/0x58)
[<c011645c>] (arm_dma_sync_single_for_device) from [<c0117088>] (arm_dma_sync_sg_for_device+0x50/0x7c)
[<c0117088>] (arm_dma_sync_sg_for_device) from [<c0c033c4>] (ion_pages_sync_for_device+0xb0/0xec)
[<c0c033c4>] (ion_pages_sync_for_device) from [<c0c054ac>] (ion_system_heap_allocate+0x2a0/0x2e0)
[<c0c054ac>] (ion_system_heap_allocate) from [<c0c02c78>] (ion_alloc+0x12c/0x494)
[<c0c02c78>] (ion_alloc) from [<c0c03eac>] (ion_ioctl+0x510/0x63c)
[<c0c03eac>] (ion_ioctl) from [<c027c4b0>] (do_vfs_ioctl+0xa8/0x9b4)
[<c027c4b0>] (do_vfs_ioctl) from [<c027ce28>] (SyS_ioctl+0x6c/0x7c)
[<c027ce28>] (SyS_ioctl) from [<c0108a40>] (ret_fast_syscall+0x0/0x48)
Code: e3a02004 e1a02312 e2423001 e1c00003 (ee070f3a)
---[ end trace 89278304932c0e87 ]---
Kernel panic - not syncing: Fatal exception

Signed-off-by: Cheng Chao <cs.os.kernel at gmail.com>
---
 drivers/staging/android/ion/ion_system_heap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index 22c481f2ae4f..2a35b99cf628 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -75,7 +75,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
 	page = ion_page_pool_alloc(pool);
 
-	if (cached)
+	if (page && cached)
 		ion_pages_sync_for_device(NULL, page, PAGE_SIZE << order,
 					  DMA_BIDIRECTIONAL);
 	return page;
-- 
2.26.3