linux-kernel - Re: "of/platform: Pause/resume sync state during init and of_platform

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Message-Id: <0A027A3B-6DE4-4C83-9884-063F74AAED94@lca.pw>
Date:   Tue, 6 Aug 2019 21:56:14 -0400
From:   Qian Cai <cai@....pw>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-kernel@...ts.infradead.org,
        Rob Herring <robh+dt@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>
Subject: Re: "of/platform: Pause/resume sync state during init and
 of_platform_populate()" with a warning on arm64



> On Aug 6, 2019, at 9:50 PM, Saravana Kannan <saravanak@...gle.com> wrote:
> 
> Thanks for confirming. I didn't think ARM64 could even boot without
> DT. I'll send a fix right away.
> 
> Any chance you can let us know what device this was tested on?

It is a HPE Apollo 70 arm64 server.

https://h20195.www2.hpe.com/v2/gethtml.aspx?docname=a00039978enw

> 
> -Saravana
> 
> 
> 
> -Saravana
> 
> On Tue, Aug 6, 2019 at 6:46 PM Qian Cai <cai@....pw> wrote:
>> 
>> 
>> 
>>> On Aug 6, 2019, at 9:22 PM, Saravana Kannan <saravanak@...gle.com> wrote:
>>> 
>>> On Tue, Aug 6, 2019 at 5:46 PM Qian Cai <cai@....pw> wrote:
>>>> 
>>>> It looks like the linux-next commit “of/platform: Pause/resume sync state during init and of_platform_populate()” [1]
>>>> Introduced a warning while booting arm64.
>>>> 
>>>> [1] https://lore.kernel.org/lkml/20190731221721.187713-6-saravanak@google.com/
>>>> 
>>>> [   93.449300][    T1] arm-smmu-v3 arm-smmu-v3.4.auto: ias 44-bit, oas 44-bit (features 0x0000170d)
>>>> [   93.464873][    T1] arm-smmu-v3 arm-smmu-v3.4.auto: allocated 524288 entries for cmdq
>>>> [   93.485481][    T1] arm-smmu-v3 arm-smmu-v3.4.auto: allocated 524288 entries for evtq
>>>> [   93.496320][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: option mask 0x2
>>>> [   93.502917][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: ias 44-bit, oas 44-bit (features 0x0000170d)
>>>> [   93.621818][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: allocated 524288 entries for cmdq
>>>> [   93.643000][    T1] arm-smmu-v3 arm-smmu-v3.5.auto: allocated 524288 entries for evtq
>>>> [   94.519445][    T1] libphy: Fixed MDIO Bus: probed
>>>> [   94.524649][    T1] EFI Variables Facility v0.08 2004-May-17
>>>> [   94.601166][    T1] NET: Registered protocol family 17
>>>> [   94.766008][    T1] zswap: loaded using pool lzo/zbud
>>>> [   94.774745][    T1] kmemleak: Kernel memory leak detector initialized (mempool size: 16384)
>>>> [   94.774756][ T1699] kmemleak: Automatic memory scanning thread started
>>>> [   94.812338][ T1368] pcieport 0000:0f:00.0: Adding to iommu group 0
>>>> [   94.984466][    T1] ------------[ cut here ]------------
>>>> [   94.989827][    T1] Unmatched sync_state pause/resume!
>>>> [   94.989894][    T1] WARNING: CPU: 25 PID: 1 at drivers/base/core.c:691 device_links_supplier_sync_state_resume+0x100/0x128
>>>> [   95.006062][    T1] Modules linked in:
>>>> [   95.009815][    T1] CPU: 25 PID: 1 Comm: swapper/0 Not tainted 5.3.0-rc3-next-20190806+ #11
>>>> [   95.018161][    T1] Hardware name: HPE Apollo 70             /C01_APACHE_MB         , BIOS L50_5.13_1.11 06/18/2019
>>>> [   95.028593][    T1] pstate: 60400009 (nZCv daif +PAN -UAO)
>>>> [   95.034077][    T1] pc : device_links_supplier_sync_state_resume+0x100/0x128
>>>> [   95.041124][    T1] lr : device_links_supplier_sync_state_resume+0x100/0x128
>>>> [   95.048167][    T1] sp : 34ff800806e6fbc0
>>>> [   95.052172][    T1] x29: 34ff800806e6fc00 x28: 0000000000000000
>>>> [   95.058177][    T1] x27: 0000000000000000 x26: 0000000000000000
>>>> [   95.064181][    T1] x25: 0000000000000038 x24: 0000000000000000
>>>> [   95.070185][    T1] x23: 0000000000000000 x22: 0000000000000019
>>>> [   95.076189][    T1] x21: 0000000000000000 x20: f9ff808b804e6c50
>>>> [   95.082193][    T1] x19: ffff100014a6e600 x18: 0000000000000040
>>>> [   95.088197][    T1] x17: 0000000000000000 x16: 86ff80099d581b50
>>>> [   95.094201][    T1] x15: 0000000000000000 x14: ffff100010086d1c
>>>> [   95.100205][    T1] x13: ffff1000109d8688 x12: ffffffffffffffff
>>>> [   95.106209][    T1] x11: 00000000000000f9 x10: ffff0808b804e6c6
>>>> [   95.112213][    T1] x9 : 4b71ad522c851d00 x8 : 4b71ad522c851d00
>>>> [   95.118217][    T1] x7 : 6170206574617473 x6 : ffff100014076972
>>>> [   95.124221][    T1] x5 : 34ff800806e6f8f0 x4 : 000000000000000f
>>>> [   95.130225][    T1] x3 : ffff1000101bfa5c x2 : 0000000000000001
>>>> [   95.136229][    T1] x1 : 0000000000000001 x0 : 0000000000000022
>>>> [   95.142233][    T1] Call trace:
>>>> [   95.145374][    T1]  device_links_supplier_sync_state_resume+0x100/0x128
>>>> [   95.152074][    T1]  of_platform_sync_state_init+0x10/0x1c
>>>> [   95.157557][    T1]  do_one_initcall+0x2f8/0x600
>>>> [   95.162172][    T1]  do_initcall_level+0x37c/0x3fc
>>>> [   95.166959][    T1]  do_basic_setup+0x34/0x4c
>>>> [   95.171313][    T1]  kernel_init_freeable+0x188/0x24c
>>>> [   95.176363][    T1]  kernel_init+0x18/0x334
>>>> [   95.180543][    T1]  ret_from_fork+0x10/0x18
>>>> [   95.184809][    T1] ---[ end trace a9ea68c902540fe5 ]---
>>>> [   95.269085][    T1] Freeing unused kernel memory: 28672K
>>>> [  101.069860][    T1] Checked W+X mappings: passed, no W+X pages found
>>>> [  101.076265][    T1] Run /init as init process
>>>> [  101.186359][    T1] systemd[1]: System time before build time, advancing clock.
>>> 
>>> 
>>> I tested it again on my device (on an older kernel) and I don't see
>>> this warning. Is this on an ARM64 target without a populated DT?
>> 
>> Probably, /sys/firmware/devicetree is all empty.
>> 
>>> That's the only thing I can see that could cause this warning.
>>> 
>>> This is literally the code with the matching pause/resume. I can't
>>> think of any other way the pause/resume could have ended up not
>>> matching.
>>> 
>>> static int __init of_platform_default_populate_init(void)
>>> {
>>>       struct device_node *node;
>>> 
>>>       if (!of_have_populated_dt())
>>>               return -ENODEV;
>>> 
>>>       platform_bus_type.add_links = of_link_to_suppliers;
>>>       device_links_supplier_sync_state_pause(); <=========== PAUSE
>>>       /*
>>>        * Handle certain compatibles explicitly, since we don't want to create
>>>        * platform_devices for every node in /reserved-memory with a
>>>        * "compatible",
>>>        */
>>>       for_each_matching_node(node, reserved_mem_matches)
>>>               of_platform_device_create(node, NULL, NULL);
>>> 
>>>       node = of_find_node_by_path("/firmware");
>>>       if (node) {
>>>               of_platform_populate(node, NULL, NULL, NULL);
>>>               of_node_put(node);
>>>       }
>>> 
>>>       /* Populate everything else. */
>>>       of_platform_default_populate(NULL, NULL, NULL);
>>> 
>>>       return 0;
>>> }
>>> arch_initcall_sync(of_platform_default_populate_init);
>>> 
>>> static int __init of_platform_sync_state_init(void)
>>> {
>>>       device_links_supplier_sync_state_resume(); <========= RESUME
>>>       return 0;
>>> }
>>> late_initcall_sync(of_platform_sync_state_init);
>>> 
>>> Thanks,
>>> Saravana
>>