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Date:   Mon, 14 Oct 2019 18:09:01 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     John Garry <john.garry@huawei.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        James Morse <james.morse@arm.com>, tony.luck@intel.com,
        Robert Richter <rrichter@marvell.com>,
        linux-edac@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: edac KASAN warning in experimental arm64 allmodconfig boot
Message-ID: <20191014160901.GE4715@zn.tnic>
References: <304df85b-8b56-b77e-1a11-aa23769f2e7c@huawei.com>
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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), 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?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette