From: "Pratyush Yadav (Google)" The KHO restoration machinery is not capable of dealing with preservations that span multiple NUMA nodes. kho_preserve_folio() guarantees the preservation will only span one NUMA node since folios can't span multiple nodes. This leaves kho_preserve_pages(). While semantically kho_preserve_pages() only deals with 0-order pages, so all preservations should be single page only, in practice it combines preservations to higher orders for efficiency. This can result in a preservation spanning multiple nodes. Break up the preservations into a smaller order if that happens. Suggested-by: Pasha Tatashin Signed-off-by: Pratyush Yadav (Google) --- Notes: Ref: https://lore.kernel.org/linux-mm/CA+CK2bDvaGmfkCPCMWM6gPcd4FfUyD6e5yWE+kNcma1vT3Jw3g@mail.gmail.com/ kernel/liveupdate/kexec_handover.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c index cc68a3692905..bc9bd18294ee 100644 --- a/kernel/liveupdate/kexec_handover.c +++ b/kernel/liveupdate/kexec_handover.c @@ -869,9 +869,17 @@ int kho_preserve_pages(struct page *page, unsigned long nr_pages) } while (pfn < end_pfn) { - const unsigned int order = + unsigned int order = min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn)); + /* + * Make sure all the pages in a single preservation are in the + * same NUMA node. The restore machinery can not cope with a + * preservation spanning multiple NUMA nodes. + */ + while (pfn_to_nid(pfn) != pfn_to_nid(pfn + (1UL << order) - 1)) + order--; + err = __kho_preserve_order(track, pfn, order); if (err) { failed_pfn = pfn; -- 2.53.0.473.g4a7958ca14-goog