Hi Ritesh, On Saturday 19 April 2014 16:55:30 Ritesh Harjani wrote: > In explaining the issue below, made a mistake of taking PAGE_SIZE > instead of PAGE_SHIFT (mistake mentioned inline). > Although numerical values and patch is correct. I was about to send the same patch, so, provided you fix the commit message, Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > On Sat, Apr 19, 2014 at 4:49 PM, Ritesh Harjani > > <ritesh.harjani@xxxxxxxxx> wrote: > > I am finding an oops after following commit. I am on 3.10.30 kernel but > > applied all the latest patches from arch/arm/mm/dma-mapping.c > > > > I added some debug logs to see what is the error, on which I found that we > > are incorrectly setting mapping->size value. > > Please take a look at this and correct me if I am wrong here. > > > > FAULTY COMMIT: > > commit 68efd7d2fb32c2606f1da318b6a851 > > d933813f27 > > Author: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > > Date: Tue Feb 25 13:01:09 2014 +0100 > > > > arm: dma-mapping: remove order parameter from > > arm_iommu_create_mapping() > > > > OOPS LOGS: > > [26.898145] __alloc_iova#LINE: 1097 start = 0x3500 > > [26.898159] __alloc_iova#LINE:1136 iova = 0x53500000 > > [26.898170] __alloc_iova#LINE:1138 mapping->base= 0x50000000 > > [26.898181] __alloc_iova#LINE:1140 mapping->size = 0x1000000, i = 0 > > [26.924442] __free_iova, bitmap_index = 3 > > > > [Ritesh]: bitmap_index should be 0 for address 0x53500000. see in > > alloc_iova above. > > > > [26.924454] __free_iova,addr = 0x53500000 > > [26.924463] __free_iova,mapping->base = 0x50000000 > > [26.924472] __free_iova,mapping->size = 0x1000000 > > [26.924482] __free_iova,bitmap_base = 0x53000000 > > [26.924490] __free_iova, start = 0x500 > > > > [Ritesh]: start should be 0x3500 for address 0x53500000. see in alloc_iova > > above. > > > > [26.924533] Unable to handle kernel NULL pointer dereference at virtual > > address 000000a0 > > [26.924543] pgd = e7a84000 > > [26.924558] [000000a0] *pgd=00000000 > > [26.924572] Internal error: Oops: 5 [#1] PREEMPT SMP ARM > > [26.924598] Modules linked in: > > [26.924613] CPU: 1 PID: 2263 Comm: BufferLiberator Not tainted 3.10.30+ > > #144 > > [26.924624] task: e7370a40 ti: e6e06000 task.ti: e6e06000 > > [26.924644] PC is at bitmap_clear+0x48/0xd0 > > [26.924659] LR is at __iommu_remove_mapping+0x130/0x164 > > [26.924673] pc : [<c02d0814>] lr : [<c001bd30>] psr: 20000093 > > [26.924673] sp : e6e07e20 ip : ffffffff fp : e6e07e3c > > [26.924682] r10: 00000500 r9 : c1333ea8 r8 : 80000013 > > [26.924692] r7 : ffffffff r6 : 00000321 r5 : 000000a0 r4 : 00000028 > > [26.924707] r3 : 00000000 r2 : 00000341 r1 : 00000500 r0 : 00000000 > > [26.924730] Flags: nzCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment > > user > > [26.924742] Control: 10c5387d Table: 77a8406a DAC: 00000015 > > > > > > See below on how this is wrong: > > > > here iova_base = 0x50000000 > > iova_size = 0x20000000 > > => bits needed to map = 131072. > > > > => bitmap_size = 0x4000 > > since bitmap_size > PAGE_SIZE > > => bitmap_size = PAGE_SIZE, extensions = 4; > > > > Now, mapping->size is currently set as bitmap_size << PAGE_SHIFT. > > > > =>mapping->size = 0x1000000. > > > > mapping->size is the IOVA size, which one bitmap can address. > > > > Now mapping->size * extensions should be size (0x20000000). > > which is not true, => our bitmap_size is set wrong. > > > > it should be (mapping->bits << PAGE_SIZE) or say > > It should be PAGE_SHIFT here. > > > (BITS_PER_BYTE * bitmap_size << PAGE_SIZE) > > It should be PAGE_SHIFT here. > > > => (8 * 0x1000) << 12) = 0x8000000 > > > > With this IOVA_SIZE = extensions * mapping->size = 0x20000000 > > > > > > > > PATCH: > > > > Currently mapping->size is wrongly set resulting > > in OOPS (atleast we see OOPS with extension 4). > > > > Fix this. > > > > Signed-off-by: Ritesh Harjani <ritesh.harjani@xxxxxxxxx> > > --- > > > > arch/arm/mm/dma-mapping.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > > index f62aa06..d1701a2 100644 > > --- a/arch/arm/mm/dma-mapping.c > > +++ b/arch/arm/mm/dma-mapping.c > > @@ -1963,8 +1963,8 @@ arm_iommu_create_mapping(struct bus_type *bus, > > dma_addr_t base, size_t size) > > mapping->nr_bitmaps = 1; > > mapping->extensions = extensions; > > mapping->base = base; > > - mapping->size = bitmap_size << PAGE_SHIFT; > > mapping->bits = BITS_PER_BYTE * bitmap_size; > > + mapping->size = mapping->bits << PAGE_SHIFT; > > > > spin_lock_init(&mapping->lock); > > -- Regards, Laurent Pinchart _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-arm-kernel