6.17-stable review patch. If anyone has any objections, please let me know.
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From: Pratyush Yadav pratyush@kernel.org
commit b05addf6f0596edb1f82ab4059438c7ef2d2686d upstream.
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: fc33e4b44b27 ("kexec: enable KHO support for memory preservation") Signed-off-by: Pratyush Yadav pratyush@kernel.org Reviewed-by: Mike Rapoport (Microsoft) rppt@kernel.org Cc: Alexander Graf graf@amazon.com Cc: Baoquan He bhe@redhat.com Cc: Pasha Tatashin pasha.tatashin@soleen.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/kexec_handover.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/kernel/kexec_handover.c +++ b/kernel/kexec_handover.c @@ -131,12 +131,12 @@ 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);