linux-kernel - Re: [PATCH stable 6.3 v2] arch_topology: Remove early cacheinfo error message if -ENOENT

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Message-ID: <0f2e3a2b-477b-cbd7-e756-4b3f4df8e045@broadcom.com>
Date:   Wed, 31 May 2023 12:52:22 -0700
From:   Florian Fainelli <florian.fainelli@...adcom.com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Conor Dooley <conor@...nel.org>, stable@...r.kernel.org,
        Pierre Gondois <pierre.gondois@....com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "open list:GENERIC ARCHITECTURE TOPOLOGY" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH stable 6.3 v2] arch_topology: Remove early cacheinfo error
 message if -ENOENT



On 5/31/2023 8:43 AM, Sudeep Holla wrote:
> On Wed, May 31, 2023 at 08:28:26AM -0700, Florian Fainelli wrote:
>>
>>
>> On 5/31/2023 1:53 AM, Sudeep Holla wrote:
>>> On Tue, May 30, 2023 at 03:42:45PM -0700, Florian Fainelli wrote:
>>>> Hi Conor,
>>>>
>>>> On 5/30/23 14:39, Conor Dooley wrote:
>>>>> Yo Florian,
>>>>>
>>>>> On Tue, May 30, 2023 at 01:19:55PM -0700, Florian Fainelli wrote:
>>>>>> From: Pierre Gondois <pierre.gondois@....com>
>>>>>>
>>>>>> commit 3522340199cc060b70f0094e3039bdb43c3f6ee1 upstream
>>>>>>
>>>>>> fetch_cache_info() tries to get the number of cache leaves/levels
>>>>>> for each CPU in order to pre-allocate memory for cacheinfo struct.
>>>>>> Allocating this memory later triggers a:
>>>>>>      'BUG: sleeping function called from invalid context'
>>>>>> in PREEMPT_RT kernels.
>>>>>>
>>>>>> If there is no cache related information available in DT or ACPI,
>>>>>> fetch_cache_info() fails and an error message is printed:
>>>>>>      'Early cacheinfo failed, ret = ...'
>>>>>>
>>>>>> Not having cache information should be a valid configuration.
>>>>>> Remove the error message if fetch_cache_info() fails with -ENOENT.
>>>>>>
>>>>>> Suggested-by: Conor Dooley <conor.dooley@...rochip.com>
>>>>>> Link: https://lore.kernel.org/all/20230404-hatred-swimmer-6fecdf33b57a@spud/
>>>>>> Signed-off-by: Pierre Gondois <pierre.gondois@....com>
>>>>>> Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
>>>>>> Link: https://lore.kernel.org/r/20230414081453.244787-4-pierre.gondois@arm.com
>>>>>> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
>>>>>> Signed-off-by: Florian Fainelli <florian.fainelli@...adcom.com>
>>>>>
>>>>> How come this now needs a backport? Did the rest of the series get
>>>>> backported, but not this one since it has no fixes tag?
>>>>
>>>> Humm, indeed, this has been present in v6.3.2 since I requested it to be
>>>> included. The error that I saw this morning was not -ENOENT, but -EINVAL.
>>>>
>>>> With those patches applied, no more -EINVAL:
>>>>
>>>> cacheinfo: Allow early level detection when DT/ACPI info is missing/broken
>>>> cacheinfo: Add arm64 early level initializer implementation
>>>> cacheinfo: Add arch specific early level initializer
>>>> cacheinfo: Add use_arch[|_cache]_info field/function
>>>>
>>>> I will submit those shortly unless we think they better not be in 6.3, in
>>>> which case it would be nice to silence those -EINVAL errors.
>>>
>>> I prefer this option instead of back porting all the above 4 as there are
>>> some pending fixes for the issues found in those patches. I am fine if Greg
>>> is happy with the backport, so no strong rejection from my side :).
>>
>> OK, so are you suggesting that we specific check for -EINVAL and -ENOENT
>> rather than take all of the 4 above patches,
> 
> Yes that is my preference ATM or if possible to wait until all the fixes
> are sorted for the bugs associated with above 4 commits [1] and [2].
> I have queued [1] but waiting for response/patch on [2] and hence not yet
> bothered Greg.
> 
>> if so, any preference on how to do it given the state of 6.3 stable?
> 
> I don't understand what exactly do you mean ?

Linux 6.3.y currently contains:

cacheinfo: Check sib_leaf in cache_leaves_are_shared()
cacheinfo: Check cache properties are present in DT
arch_topology: Remove early cacheinfo error message if -ENOENT

however my logs are full of:

[    0.001484] Early cacheinfo failed, ret = -22

reverting these 3 patches mentioned above does not eliminate the error.

What I am asking is if we need a targeted fix for 6.3 like this:

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index c4b6198d7461..a72fcf836ed3 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -845,7 +845,7 @@ void __init init_cpu_topology(void)
                  ret = fetch_cache_info(cpu);
                  if (!ret)
                          continue;
-               else if (ret != -ENOENT)
+               else if (ret != -ENOENT && ret != -EINVAL)
                          pr_err("Early cacheinfo failed, ret = %d\n", ret);
                  return;
          }

-- 
Florian


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