On Thu, Oct 25 2007, Amit Shah wrote:
> I get a kernel panic at gart_map_sg+0x201/0x470, which is around here:
>
> out++;
> flush_gart();
> if (out < nents) {
> sgmap = sg_next(sgmap);
> sgmap->dma_length = 0;
> }
> return out;
>
> 8e5: e8 d6 fc ff ff callq 5c0 <flush_gart>
> 8ea: ff c3 inc %ebx
> 8ec: 41 39 df cmp %ebx,%r15d
> 8ef: 0f 8e 9d 00 00 00 jle 992 <gart_map_sg+0x292>
> 8f5: 31 c9 xor %ecx,%ecx
> 8f7: f6 45 00 02 testb $0x2,0x0(%rbp)
> 8fb: 0f 84 1f 02 00 00 je b20 <gart_map_sg+0x420>
> 901: c7 41 18 00 00 00 00 movl $0x0,0x18(%rcx)
> 908: e9 85 00 00 00 jmpq 992 <gart_map_sg+0x292>
> 90d: 0f 1f 00 nopl (%rax)
> 910: 44 89 e0 mov %r12d,%eax
> 913: 29 f0 sub %esi,%eax
> 915: 45 85 d2 test %r10d,%r10d
> 918: 89 c6 mov %eax,%esi
> 91a: 0f 85 02 ff ff ff jne 822 <gart_map_sg+0x122>
> 920: ff ce dec %esi
> 922: 75 65 jne 989 <gart_map_sg+0x289>
>
>
> My system is an AMD Opteron 1216. I'm not sure if only adding a check
> for sgmap != NULL after sg_next is the right fix.
Tomo already nailed this one, see below.
From: FUJITA Tomonori <[email protected]>
Subject: [PATCH] x86: pci-gart fix
map_sg could copy the last sg element to another position (if merging
some elements). It breaks sg chaining. This copies only
dma_address/length instead of the whole sg element.
Signed-off-by: FUJITA Tomonori <[email protected]>
---
arch/x86/kernel/pci-gart_64.c | 3 +--
1 files changed, 1 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c
index c56e9ee..ae7e016 100644
--- a/arch/x86/kernel/pci-gart_64.c
+++ b/arch/x86/kernel/pci-gart_64.c
@@ -338,7 +338,6 @@ static int __dma_map_cont(struct scatterlist *start, int nelems,
BUG_ON(s != start && s->offset);
if (s == start) {
- *sout = *s;
sout->dma_address = iommu_bus_base;
sout->dma_address += iommu_page*PAGE_SIZE + s->offset;
sout->dma_length = s->length;
@@ -365,7 +364,7 @@ static inline int dma_map_cont(struct scatterlist *start, int nelems,
{
if (!need) {
BUG_ON(nelems != 1);
- *sout = *start;
+ sout->dma_address = start->dma_address;
sout->dma_length = start->length;
return 0;
}
--
1.5.2.4
--
Jens Axboe
-
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