From: Cheng Chao cs.os.kernel@gmail.com
Fixes: commit e7f63771b60e ("ION: Sys_heap: Add cached pool to spead up cached buffer alloc") the commit e7f63771b60e introduced the bug which didn't test page which maybe NULL. and previous logic was right.
the e7f63771b60e has been merged in v4.8-rc3, only longterm 4.9.x has this bug, and other longterm/stable version have not.
kernel panic is here when page is NULL:
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@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/staging/android/ion/ion_system_heap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- 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(st
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;