ACK: [SRU][O][PATCH 0/3] Fix BQL crashes, most frequently observed on GCP instances

[Ian Whitfield]

On Wed, Dec 11, 2024 at 03:06:29PM +0900, Koichiro Den wrote:
> BugLink: https://bugs.launchpad.net/bugs/2089684
> 
> SRU Justification
> 
> [Impact]
> 
> Since upstream commit c8bd1f7f3e61 ("virtio_net: add support for Byte Queue
> Limits"), BQL crashes have been observed. One crash pattern was addressed
> by upstream commit b96ed2c97c79 ("virtio_net: move netdev_tx_reset_queue()
> call before RX napi enable"), but other patterns remain unresolved. Most
> notably, on GCP instances, frequent boot test failures with BQL crashes
> have been found. To end users, this issue typically appears as extremely
> slow instance boot time. Even when booting is successful, the instance
> remains susceptible to kernel panics under certain conditions. So this
> issue needs to be resolved. Only Oracular is affected.
> 
> [Fix]
> 
> The issue is resolved by the following patch series:
> https://lore.kernel.org/all/20241206011047.923923-1-koichiro.den@canonical.com/
> 6.11.y branch is now EOL, so the patch series will not land in upstream
> stable tree.
> 
> [Test Plan]
> 
> Reboot some GCP instances with the fix applied multiple times to verify
> that the BQL crash no longer occurs.
> 
> [Where problems could occur]
> 
> The fix impacts only virtio-net, so any regression would appear as
> unexpected behavior in virtio-net or potentially cause a kernel crash.
> 
> [Other Info]
> 
> [PATCH 1/3] resolves the issue observed on GCP.
> [PATCH 2/3] + [PATCH 3/3] resolve similar issues which have not been
> observed on our testing infrastructure but still worth applying to
> prevent potential kernel panic due to BQL crash.
> 
> 
> Koichiro Den (3):
>   virtio_net: correct netdev_tx_reset_queue() invocation point
>   virtio_ring: add a func argument 'recycle_done' to virtqueue_resize()
>   virtio_net: ensure netdev_tx_reset_queue is called on tx ring resize
> 
>  drivers/net/virtio_net.c     | 24 +++++++++++++++++++++---
>  drivers/virtio/virtio_ring.c |  6 +++++-
>  include/linux/virtio.h       |  3 ++-
>  3 files changed, 28 insertions(+), 5 deletions(-)
> 
> -- 
> 2.43.0
> 
> 
> -- 
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Acked-by: Ian Whitfield <ian.whitfield at canonical.com>