APPLIED: [SRU][P:linux][PATCH 0/1 v2] deadlock on cpu_hotplug_lock in __accept_page()

[Mehmet Basaran]

Thibault Ferrante <thibault.ferrante at canonical.com> writes:

Applied to plucky:linux master-next branch. Thanks.

> BugLink: https://bugs.launchpad.net/bugs/2109543
>
> [ Impact ]
>
>  * Boot hangs because of deadlock caused by mm (memory management)
>    during CPU bring-up.
>
> [ Fix ]
>
>  * Upstream commit :
>    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4067196a52278156d18d8d6fa7f43970611b1b49
>
> [ Test Plan ]
>
>  * This deadlock has been uncovered in the context of confidential VMs work (AMD SNP & TDX)
>    since its appearance frequency has been increased by the introduction of another commit
>    for fixing an unrelated issue when booting a large memory profile TDX VM.
>    (https://lore.kernel.org/all/20250310082855.2587122-1-kirill.shutemov@linux.intel.com/#t)
>
>    Per consequence, to have a better chance to reproduce the issue, run a AMD SNP or TDX VM
>    with a certain CPU configuration:
>
>    For AMD SNP,  you can follow the instructions in the submission
>    https://lore.kernel.org/all/363f8293-23e3-44d3-8005-b31eb5b7f975@amd.com/#t
>
>    For Intel TDX, we can also reproduce this issue with Intel TDX VM with our 6.14 -intel kernel that has
>    TDX feature enabled (since TDX feature is only in kernel main-next for now and not yet released).
>
> [ Where problems could occur ]
>
>  * Performance regression in memory allocation and regression at CPU bring up time.
>
> [ Further information ]
>
>  * It is necessary to backport this patch to Plucky and Oracular kernel since
>    the commit that exhibits this deadlock is in Plucky 6.14 and being backported
>    to Oracular 6.11 kernel, however as the backport is not trivial, this will be
>    coming in a subsequent submission.
>
> v1 -> v2:
>  Updated problem section.
>  Provenance/SOB added to the patch.
>  More explication on Oracular inclusion.
>  
> Kirill A. Shutemov (1):
>   mm/page_alloc: fix deadlock on cpu_hotplug_lock in __accept_page()
>
>  include/linux/mmzone.h |  3 +++
>  mm/internal.h          |  1 +
>  mm/mm_init.c           |  1 +
>  mm/page_alloc.c        | 28 ++++++++++++++++++++++++++--
>  4 files changed, 31 insertions(+), 2 deletions(-)
>
> -- 
> 2.48.1
>
>
> -- 
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> kernel-team at lists.ubuntu.com
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