linux-kernel - Re: [PATCH] acpi, pci, irq: account for early penalty assignment

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Date:	Wed, 24 Feb 2016 14:04:48 +0100
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Sinan Kaya <okaya@...eaurora.org>
Cc:	"Rafael J. Wysocki" <rafael@...nel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Timur Tabi <timur@...eaurora.org>,
	Christopher Covington <cov@...eaurora.org>,
	Linux PCI <linux-pci@...r.kernel.org>, ravikanth.nalla@....com,
	Len Brown <lenb@...nel.org>, harish.k@....com,
	ashwin.reghunandanan@....com, Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] acpi, pci, irq: account for early penalty assignment

Hi,

On Tue, Feb 16, 2016 at 3:15 AM, Sinan Kaya <okaya@...eaurora.org> wrote:
> On 2/15/2016 7:26 PM, Rafael J. Wysocki wrote:
>> On Mon, Feb 15, 2016 at 5:41 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
>>> A crash has been observed when assigning penalty on x86 systems.
>>>
>>> It looks like this problem happens on x86 platforms with IOAPIC and an SCI
>>> interrupt override in the ACPI table with interrupt number greater than
>>> 16. (22 in this example)
>>>
>>> The bug has been introduced by "ACPI, PCI, irq: remove interrupt count
>>> restriction" commit. The code was using kmalloc to resize the interrupt
>>> list. In this use case, the set penalty call is coming from early phase
>>> and the heap is not initialized yet.
>>>
>>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
>>> IP: [<ffffffff811e8b9d>] kmem_cache_alloc_trace+0xad/0x1c0
>>> PGD 0
>>> Oops: 0000 [#1] SMP
>>> Modules linked in:
>>> CPU: 0 PID: 0 Comm: swapper Not tainted 4.5.0-rc2Feb-3_RK #1
>>> Hardware name: HP Superdome2 16s, BIOS Bundle: 007.006.000 SFW: 033.162.000
>>> 10/30/2015
>>> [<ffffffff813bc190>] acpi_irq_set_penalty+0x60/0x8e
>>> [<ffffffff813bc1df>] acpi_irq_add_penalty+0x21/0x26
>>> [<ffffffff813bc76d>] acpi_penalize_sci_irq+0x25/0x28
>>> [<ffffffff81b8260d>] acpi_sci_ioapic_setup+0x68/0x78
>>> [<ffffffff81b830fc>] acpi_boot_init+0x2cc/0x533
>>> [<ffffffff810677c8>] ? set_pte_vaddr_pud+0x48/0x50
>>> [<ffffffff81b828cf>] ? acpi_parse_x2apic+0x77/0x77
>>> [<ffffffff81b82858>] ? dmi_ignore_irq0_timer_override+0x30/0x30
>>> [<ffffffff81b77c1e>] setup_arch+0xc24/0xce9
>>> [<ffffffff81b6e120>] ? early_idt_handler_array+0x120/0x120
>>> [<ffffffff81b6ed94>] start_kernel+0xfc/0x506
>>> [<ffffffff81b6e120>] ? early_idt_handler_array+0x120/0x120
>>> [<ffffffff81b6e120>] ? early_idt_handler_array+0x120/0x120
>>> [<ffffffff81b6e5ee>] x86_64_start_reservations+0x2a/0x2c
>>> [<ffffffff81b6e73c>] x86_64_start_kernel+0x14c/0x16f
>>>
>>> Besides from the use case above, there is one more situation where
>>> set_penalty is being called from the init context like. There is support
>>> for setting the penalty through kernel command line.
>>>
>>> Adding support to be called from early context for limited number of
>>> interrupts.
>>>
>>> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
>>
>> This looks somewhat hackish to me to be honest.
> I know.

So after an e-mail exchange with Bjorn I've decided to revert the
problematic commit for 4.5, so please submit it again with the fix
folded in (or a better way to address the issue if you have one).

Thanks,
Rafael