linux-kernel - Re: edac KASAN warning in experimental arm64 allmodconfig boot

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Date:   Mon, 14 Oct 2019 17:44:13 +0100
From:   John Garry <john.garry@...wei.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        James Morse <james.morse@....com>, <tony.luck@...el.com>,
        Robert Richter <rrichter@...vell.com>,
        <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: edac KASAN warning in experimental arm64 allmodconfig boot

On 14/10/2019 17:09, Borislav Petkov wrote:
> On Mon, Oct 14, 2019 at 04:18:49PM +0100, John Garry wrote:
>> Hi guys,
>>
>> I'm experimenting by trying to boot an allmodconfig arm64 kernel, as
>> mentioned here:
>> https://lore.kernel.org/linux-arm-kernel/507325a3-030e-2843-0f46-7e18c60257de@huawei.com/
>>
>> One thing that I noticed - it's hard to miss actually - is the amount of
>> complaining from KASAN about the EDAC/ghes code. Maybe this is something I
>> should not care about/red herring, or maybe something genuine. Let me know
>> what you think.
>>
>> The kernel is v5.4-rc3, and I raised the EDAC mc debug level to get extra
>> debug prints.
>>
>> Log below, Thanks,
>> John
>> Log snippet (I cut off after the first KASAN warning):
>>
>> [   70.471011][    T1] random: get_random_u32 called from new_slab+0x360/0x698 with crng_init=0
>> [   70.478671][    T1] [Firmware Bug]: APEI: Invalid bit width + offset in GAR [0x94110034/64/0/3/0]
>> [   70.526585][    T1] EDAC DEBUG: edac_mc_alloc: allocating 3524 bytes for mci data (32 dimms, 32 csrows/channels)
>> [   70.542013][    T1] EDAC DEBUG: ghes_edac_dmidecode: DIMM2: Registered-DDR4 size = 16384 MB(ECC)
>> [   70.551044][    T1] EDAC DEBUG: ghes_edac_dmidecode:         type 26, detail 0x2080, width 72(total 64)
>> [   70.559986][    T1] EDAC DEBUG: edac_mc_add_mc_with_groups:
>> [   70.567082][    T1] EDAC DEBUG: edac_create_sysfs_mci_device: device mc0 created
>> [   70.575608][    T1] EDAC DEBUG: edac_create_dimm_object: device dimm2 created at location memory 2
>> [   70.585818][    T1] EDAC DEBUG: edac_create_csrow_object: device csrow2 created
>> [   70.594110][    T1] EDAC MC0: Giving out device to module ghes_edac.c controller ghes_edac: DEV ghes (INTERRUPT)
>> [   70.605936][    T1] EDAC DEBUG: edac_mc_del_mc:
>> [   70.611188][    T1] EDAC DEBUG: edac_remove_sysfs_mci_device:
>> [   70.619443][    T1] random: get_random_u32 called from kobject_put+0x8c/0x190 with crng_init=0
>> [   70.628163][    T1] kobject: 'csrow2' ((____ptrval____)): kobject_release, parent (____ptrval____) (delayed 750)
>> [   70.638477][    T1] EDAC DEBUG: edac_remove_sysfs_mci_device: unregistering device dimm2
>> [   70.647903][    T1] kobject: 'dimm2' ((____ptrval____)): kobject_release, parent (____ptrval____) (delayed 250)
>> [   70.658105][    T1] EDAC MC: Removed device 0 for ghes_edac.c ghes_edac: DEV ghes
>> [   70.665673][    T1] EDAC DEBUG: edac_mc_free:
>> [   70.670211][    T1] EDAC DEBUG: edac_unregister_sysfs: unregistering device mc0
>> [   70.679027][    T1] kobject: 'mc0' ((____ptrval____)): kobject_release, parent (____ptrval____) (delayed 500)
>> [   70.690987][    T1] EDAC DEBUG: edac_mc_del_mc:
>> [   70.695769][    T1] EDAC DEBUG: edac_mc_free:
>> [   70.700412][    T1] ------------[ cut here ]------------
>> [   70.705832][    T1] ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x48
>> [   70.716663][    T1] WARNING: CPU: 50 PID: 1 at lib/debugobjects.c:484 debug_print_object+0xec/0x130
>
> If I am parsing these unwrapped messages correctly (btw, pls use another
> mail client for pasting log lines - thunderbird is usually ok but I
> guess you need to configure it properly

Maybe you can receive the cutdown log attachment while I figure out how 
to do that...

), that must be some workqueue
> object of sorts.
>
> Now, ghes_edac doesn't init the workqueue:
>
> [   70.594110][    T1] EDAC MC0: Giving out device to module ghes_edac.c controller ghes_edac: DEV ghes (INTERRUPT)
>
> as it is in interrupt mode.
>
> So the only other workqueue I see is that "delayed XXX" stuff which is in
> kobject_release().
>
> AFAICT.
>
> Do you have CONFIG_DEBUG_KOBJECT_RELEASE enabled and if so, does the
> warning go away if you disable it?
>

Yes, it's enabled with allmodconfig, but no, it does not go away with 
disabling (see log #2).

Cheers,
John

> Thx.
>


View attachment "kasan edac log 2" of type "text/plain" (14252 bytes)

View attachment "kasan edac log" of type "text/plain" (25719 bytes)