The following was reported by Joshua Hoblitt on Gentoo bugzilla when using the arcmsr driver (see https://bugs.gentoo.org/208493) When starting up the Areca RAID card http pass through proxy called archttp dmesg is completely filled with messages as: WARNING: at arch/x86/kernel/pci-dma_64.c:169 dma_free_coherent() Pid: 8232, comm: archttp64 Not tainted 2.6.24-gentoo #1 Call Trace: [<ffffffff80212f24>] dma_alloc_coherent+0x1ba/0x1d2 [<ffffffff80212c53>] dma_free_coherent+0x43/0x82 [<ffffffff88044b65>] :arcmsr:arcmsr_queue_command+0x368/0x959 [<ffffffff8042078f>] scsi_dispatch_cmd+0x1a9/0x1fe [<ffffffff804259c4>] scsi_request_fn+0x26f/0x33e [<ffffffff8038a781>] blk_execute_rq_nowait+0x7a/0x8e [<ffffffff80425471>] scsi_execute_async+0x345/0x394 [<ffffffff8022d813>] __wake_up_common+0x41/0x74 [<ffffffff8045b9dc>] sg_common_write+0x6b7/0x6ef [<ffffffff8045bc31>] sg_cmd_done+0x0/0x1d6 [<ffffffff8022e200>] __dequeue_entity+0x1c/0x32 [<ffffffff8045bc0e>] sg_new_write+0x1fa/0x21d [<ffffffff8045c31a>] sg_ioctl+0x218/0xa31 [<ffffffff8024dc70>] hrtimer_cancel+0xc/0x16 [<ffffffff8058d483>] do_nanosleep+0x55/0x7e [<ffffffff8024de3b>] hrtimer_nanosleep+0x5b/0xfe [<ffffffff802a5539>] do_ioctl+0x55/0x6b [<ffffffff802a579c>] vfs_ioctl+0x24d/0x266 [<ffffffff802a57f1>] sys_ioctl+0x3c/0x5f [<ffffffff8020be2e>] system_call+0x7e/0x83 ---------------------- The warning was added in dma_free_coherent() (pci-dma_64.c and pci-dma_32.c) in kernel 2.6.24 to avoid portability issues with drivers using this function. The commit details why this warning was added: -------------------- dma_free_coherent() needs irqs enabled (sigh) On at least ARM (and I'm told MIPS too) dma_free_coherent() has a newish call context requirement: unlike its dma_alloc_coherent() sibling, it may not be called with IRQs disabled. (This was new behavior on ARM as of late 2005, caused by ARM SMP updates.) This little surprise can be annoyingly driver-visible. Since it looks like that restriction won't be removed, this patch changes the definition of the API to include that requirement. Also, to help catch nonportable drivers, it updates the x86 and swiotlb versions to include the relevant warnings. (I already observed that it trips on the bus_reset_tasklet of the new firewire_ohci driver.) -------------- the commit can be seen here: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=aa24886e379d2b641c5117e178b15ce1d5d366ba If additional info is needed this can be provided and we would be happy to ask the user to test any available patches. Best regards Kim Højgaard-Hansen Gentoo Kernel team - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
