Hi, > > With CONFIG_DEBUG_SG is enabled and when dma mode is used, below > dump > > is seen, > > > > ------------[ cut here ]------------ > > kernel BUG at include/linux/scatterlist.h:140! > > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: > > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-00459-g9f087b9-dirty > > #7 Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT) > > task: ffffffc036868000 ti: ffffffc036870000 task.ti: ffffffc036870000 > > PC is at qup_sg_set_buf.isra.13+0x138/0x154 > > LR is at qup_sg_set_buf.isra.13+0x50/0x154 pc : [<ffffffc0005a0ed8>] > > lr : [<ffffffc0005a0df0>] pstate: 60000145 sp : ffffffc0368735c0 > > x29: ffffffc0368735c0 x28: ffffffc036873752 > > x27: ffffffc035233018 x26: ffffffc000c4e000 > > x25: 0000000000000000 x24: 0000000000000004 > > x23: 0000000000000000 x22: ffffffc035233668 > > x21: ffffff80004e3000 x20: ffffffc0352e0018 > > x19: 0000004000000000 x18: 0000000000000028 > > x17: 0000000000000004 x16: ffffffc0017a39c8 > > x15: 0000000000001cdf x14: ffffffc0019929d8 > > x13: ffffffc0352e0018 x12: 0000000000000000 > > x11: 0000000000000001 x10: 0000000000000001 > > x9 : ffffffc0012b2d70 x8 : ffffff80004e3000 > > x7 : 0000000000000018 x6 : 0000000030000000 > > x5 : ffffffc00199f018 x4 : ffffffc035233018 > > x3 : 0000000000000004 x2 : 00000000c0000000 > > x1 : 0000000000000003 x0 : 0000000000000000 > > > > Process swapper/0 (pid: 1, stack limit = 0xffffffc036870020) > > Stack: (0xffffffc0368735c0 to 0xffffffc036874000) > > > > Change allocation of sg buffers from dma_coherent memory to kzalloc to > > fix the issue. > > This description describes what you do. But not why it is the correct solution > to the OOPS. The OOPS neither describes it. Please add some more > explanation. > Ok,will describe it more. The reason it oops is sg_set_bug expects that the buf parameter passed in should be a from the lowmem and a valid pageframe. This is not true for pages from dma_alloc_coherent which can be carveouts, hence the check fails. Allocating buffers using kzalloc fixes the issue. Regards, Sricharan -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
