** Also affects: linux (Ubuntu Focal)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Hirsute)
Importance: Undecided
Status: Confirmed
** Also affects: linux (Ubuntu Xenial)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Groovy)
Importance: Undecided
Status: New
** Description changed:
- This appears to be a problem in the ath10k module. I am not sure what it
- is exactly.
+ == SRU Justification ==
+ Whenever a buggy NAPI driver returns more than its budget, it will
+ trigger a stack trace warning with:
+ WARN_ON_ONCE(work > weight);
+
+ The warning message looks like this :
+ WARNING: CPU: 2 PID: 0 at
/build/linux-hwe-ymdo11/linux-hwe-4.15.0/net/core/dev.c:5672
net_rx_action+0x276/0x3b0
+
+ This is not very useful for debugging purpose, since it does not tell
+ you what's going on there.
+
+ == Fix ==
+ * 427d5838e996 ("net: napi: remove useless stack trace")
+
+ This patch will emit a message giving the function name, and a
+ descriptive message like:
+ NAPI poll function ath10k_pci_napi_poll+0x0/0x120 [ath10k_pci] returned
0, exceeding its budget of 64.
+
+ This patch is a clean-cherry for all the releases except Xenial.
+ For Xenial it will need to be applied with -C1
+
+ == Test ==
+ Test kernels can be found here:
+ https://people.canonical.com/~phlin/kernel/lp-1903596-napi-warnon/
+
+ Please note that even though I tried to reproduce this on a XPS 13
+ 9360 mentioned in this bug report that shipped with Atheros QCA6174
+ [168c:003e] wireless card, but I can't trigger this warning message.
+ The bug opener is also unable to test this due to some other reasons.
+
+ Howeve I did tried to trigger this warning forcibly by putting it
+ outside the if statement with the test kernels in the following link
+ to make sure it won't cause some other problem.
+
+ https://people.canonical.com/~phlin/kernel/lp-1903596-napi-warnon/force-
+ to-warn/
+
+ == Where problems could occur ==
+ For this bug itself, this patch does not really solve the problem
+ but it will provide more debug information for developers in the
+ future (and since this is just a warning message, it should be fine).
+ We can expect to see more a detailed report against ath10k driver
+ in the future on launchpad.
+
+
+ == Original Bug Report ==
+ This appears to be a problem in the ath10k module. I am not sure what it is
exactly.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.15.0-122-generic 4.15.0-122.124~16.04.1
ProcVersionSignature: Ubuntu 4.15.0-122.124~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-122-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.26
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Nov 9 13:35:54 2020
DistributionChannelDescriptor:
- # This is a distribution channel descriptor
- # For more information see
http://wiki.ubuntu.com/DistributionChannelDescriptor
- canonical-oem-somerville-xenial-amd64-20160624-2
+ # This is a distribution channel descriptor
+ # For more information see
http://wiki.ubuntu.com/DistributionChannelDescriptor
+ canonical-oem-somerville-xenial-amd64-20160624-2
InstallationDate: Installed on 2020-11-09 (0 days ago)
InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary
20160624-10:47
SourcePackage: linux-signed-hwe
UpgradeStatus: No upgrade log present (probably fresh install)
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https://bugs.launchpad.net/bugs/1903596
Title:
stack trace in kernel
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