Messages in this thread | | | From | Bjorn Helgaas <> | Date | Tue, 15 Jul 2014 14:33:41 -0600 | Subject | Re: WARNING: CPU: 2 PID: 1 at arch/x86/mm/ioremap.c:171 __ioremap_caller+0x290/0x2fa() |
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[+cc Yinghai, Rafael]
On Fri, Jul 11, 2014 at 12:11 PM, Bjorn Helgaas <bhelgaas@google.com> wrote: > On Fri, Jul 11, 2014 at 1:38 AM, Fabio Coatti <fabio.coatti@gmail.com> wrote: >> In data giovedì 10 luglio 2014 14:05:27, Bjorn Helgaas ha scritto: >>> ... >>> Fabio, can you pastebin your complete dmesg log? >> >> Sure, here you go: >> >> http://pastebin.com/FiL7N64b > > I opened this bugzilla: > https://bugzilla.kernel.org/show_bug.cgi?id=80041 and attached your > dmesg to it. I see what the problem is, but I don't have a good idea > yet for how to fix it. > > The problem is that we don't handle e820 and PNP device resource > information correctly. From the attached dmesg, we have this: > > BIOS-e820: [mem 0x00000000fed10000-0x00000000fed13fff] reserved > system 00:00: [mem 0xfed10000-0xfed17fff] could not be reserved > > The 00:00 PNP device describes the correct 32K range for the Intel MCH > (see [1] for details). But the [mem 0xfed10000-0xfed13fff] entry from > e820 was added to the resource map first, and it covers only the first > 16K of the MCH range. This caused the subsequent PNP reservation to > fail. Then the snb_uncore_imc_init_box() reservation caused the > warning, because it would be a child of the e820 entry but it covers > more space. > > [1] fixed a similar issue where the PNP device described only the > first 16K of the MCH range. This case is slightly different because > here it's the e820 entry that is incorrect. > > [1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=cb171f7abb9a
One of the reasons for iomem_resource is so we don't hand out the same address space to two different devices. We *could* do that by keeping track of the union of all devices and reserved areas that we know about.
But the current resource code is more strict: it enforces a hierarchy. For example, in this case, it rejects the 00:00 PNP resource because it is larger than the e820 entry. The problem with rejecting it is that we might hand out [mem 0xfed14000-0xfed17fff] to another device even though PNP told us that it's in use.
I'm about to head out for a few weeks of vacation, so I won't be able to do anything with this.
Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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