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

From: Florian Fainelli
Date: Wed May 31 2023 - 15:52:38 EST



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@xxxxxxx>

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@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20230404-hatred-swimmer-6fecdf33b57a@spud/
Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230414081453.244787-4-pierre.gondois@xxxxxxx
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>

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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