Messages in this thread |  | | | Date | Sat, 3 Nov 2007 14:14:53 +0100 | | From | "Torsten Kaiser" <> | | Subject | Re: 2.6.24-rc1-54866f032307063776b4eff7eadb131d47f9f9b4 fails to boot: kernel BUG at include/linux/scatterlist.h:49! |
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On 11/2/07, Stefan Richter <stefanr@s5r6.in-berlin.de> wrote: > Torsten Kaiser wrote: > > Both 2.6.24-rc1 and the current git version fail to boot for me: > > > > [ 57.182205] ohci1394: fw-host0: OHCI-1394 1.1 (PCI): IRQ=[16] > > MMIO=[effff800-efffffff] Max Packet= > > [2048] IR/IT contexts=[4/8] > > [ 57.194032] eth1394: eth2: IPv4 over IEEE 1394 (fw-host0) > > [ 57.199527] ------------[ cut here ]------------ > > [ 57.204154] kernel BUG at include/linux/scatterlist.h:49! > > To which extent do you need IEEE 1394 drivers?
Using eth1394 as primary network connection on this computer. So switching to the new stack is currently not an option, or did I missing something? (I also have a firewire disk, but that is not used right now)
> > from gdb: > > 0xffffffff80463512 is in dma_region_alloc (include/linux/scatterlist.h:49). > > 44 * In order for the low bit stealing approach to work, pages > > 45 * must be aligned at a 32-bit boundary as a minimum. > > 46 */ > > 47 BUG_ON((unsigned long) page & 0x03); > > 48 #ifdef CONFIG_DEBUG_SG > > 49 BUG_ON(sg->sg_magic != SG_MAGIC); > > 50 #endif > > 51 sg->page_link = page_link | (unsigned long) page; > > 52 } > > 53 > > Uh oh...
Looking that calltrace upwards, it seems replacing the memset(dma->sglist,...) with sg_init_table(...) would fix the BUG_ON() as that inits the SG_MAGIC. But I do not trust myself to fixing all the iterators correctly to convert this completely to the new API.
What I noticed trying to find the definition of sg_dma_address() is that all architectures seem to implement identical macros for sg_dma_address() and sg_dma_length(). The only difference is that some archs call their fields different.
But I stopped looking if unifiying all names was possible when I found swiotlb_map_sg() in lib/swiotlb.c...
Why is there a comment about using "sg_dma_{address,length}(SG)" to obtain the "appropriate dma address and length" when I see no instance of this macros there? Instead there are direct accesses to sg->length and sg->dma_length. And the field dma_length only exists in some arches! (alpha, ia64, powerpc only if __powerpc64__ is defined, sparc64 and the 64bit variant of x86) On the other hand I can't find any other "iova_length" in the hole tree apart from include/asm-parisc/scatterlist.h... ... so I can't really make sense of the sg mechanism and abstain from trying to fix this myself.
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