The patch titled Subject: kho: warn and exit when unpreserved page wasn't preserved has been added to the -mm mm-hotfixes-unstable branch. Its filename is kho-warn-and-exit-when-unpreserved-page-wasnt-preserved.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Pratyush Yadav pratyush@kernel.org Subject: kho: warn and exit when unpreserved page wasn't preserved Date: Mon, 3 Nov 2025 19:02:32 +0100

Calling __kho_unpreserve() on a pair of (pfn, end_pfn) that wasn't preserved is a bug. Currently, if that is done, the physxa or bits can be NULL. This results in a soft lockup since a NULL physxa or bits results in redoing the loop without ever making any progress.

Return when physxa or bits are not found, but WARN first to loudly indicate invalid behaviour.

Link: https://lkml.kernel.org/r/20251103180235.71409-3-pratyush@kernel.org Fixes: fc33e4b44b271 ("kexec: enable KHO support for memory preservation") Signed-off-by: Pratyush Yadav pratyush@kernel.org Cc: Alexander Graf graf@amazon.com Cc: Baoquan He bhe@redhat.com Cc: Mike Rapoport (Microsoft) rppt@kernel.org Cc: Pasha Tatashin pasha.tatashin@soleen.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

kernel/kexec_handover.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/kernel/kexec_handover.c~kho-warn-and-exit-when-unpreserved-page-wasnt-preserved +++ a/kernel/kexec_handover.c @@ -171,12 +171,12 @@ static void __kho_unpreserve(struct kho_ const unsigned long pfn_high = pfn >> order;

physxa = xa_load(&track->orders, order); - if (!physxa) - continue; + if (WARN_ON_ONCE(!physxa)) + return;

bits = xa_load(&physxa->phys_bits, pfn_high / PRESERVE_BITS); - if (!bits) - continue; + if (WARN_ON_ONCE(!bits)) + return;

clear_bit(pfn_high % PRESERVE_BITS, bits->preserve);

_

Patches currently in -mm which might be from pratyush@kernel.org are

kho-fix-out-of-bounds-access-of-vmalloc-chunk.patch kho-fix-unpreservation-of-higher-order-vmalloc-preservations.patch kho-warn-and-exit-when-unpreserved-page-wasnt-preserved.patch