On Sat, Feb 23, 2013 at 7:01 AM, Mauro Carvalho Chehab
<mchehab@xxxxxxxxxx> wrote:
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WARNING: at lib/dma-debug.c:933 check_unmap+0x407/0x8a0()
Hardware name: M720-US3
skge 0000:01:09.0: DMA-API: device driver failed to check map
error[device address=0x0000000105d52522] [size=90 bytes] [mapped as single]
Modules linked in:
…uetooth rfkill ip6t_REJECT nf_conntrack_ipv6 nf_conntrack_ipv4
nf_defrag_ipv6 nf_defrag_ipv4 xt_conntrack ip6table_filter nf_conntrack
ip6_tables… vhost_net tun macvtap… macvlan… nfsd auth_rpcgss nfs_acl
lockd… r8169… mii skge… sunrpc
Funny enough, it is also a DMA error...
I'm starting to suspect that maybe some change at the dma stack made
it a little more pedantic ;)
Yes. In 3.8.
Two similar errors on different drivers is enough for me to take a deeper
look into it to solve the mystery ;)
Basically, those got generated by lib/dma-debug.c.
On the af9015 case, this is a simple test, done at debug_dma_map_page().
It checks if the area is in stack and print an error. I suspect that, on
x86, the driver will still run, on most cases.
In the case of the network driver, it detected that
debug_dma_mapping_error() was never called. Also, I believe that the
network driver will still work, and this is more a warning that bad
things might happen with the driver, if the check is not done.
No, you don't call debug_dma_mapping_error directly. That's used by the
DMA-API debugging functions itself. It's not something drivers call.
I _suspect_ that the network driver is calling dma_map_single() or
dma_map_page() but not calling dma_map_error().
Close. It's calling pci_map_single and not calling pci_dma_mapping_error.
Those are PCI wrappers around the same functions, but that's what they
should be using.
The only network driver there on the list of drivers on your error is r8169.
Weird enough, at least on linux-next, r8169 seems ok:
Er... his error was triggered by skge, which is a network driver.
$ git grep -L dma_mapping_error $(git grep -l -e dma_map_single -e dma_map_page drivers/net/)
That's the wrong function to grep for in most cases. I don't think the
prbolem is as wide-spread as you fear.
Poma, you should probably just start filing bugs for things you hit.
In this case, the skge backtrace is just a warning but it can be fixed
up relatively easily.
