[SRU][Plucky][PATCH 0/1] mm/page_alloc: fix deadlock on cpu_hotplug_lock in __accept_page()

[Hector Cao]

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 ]

 * Problems could occur during system boot and CPU bring up

[ 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 6.8 kernel
   (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2109530)

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(-)

-- 
2.45.2