From 6cf06c17e94f26c290fd3370a5c36514ae15ac43 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 16 Jun 2022 18:41:49 +1000 Subject: [PATCH] powerpc/mm: Move CMA reservations after initmem_init() After commit 11ac3e87ce09 ("mm: cma: use pageblock_order as the single alignment") there is an error at boot about the KVM CMA reservation failing, eg: kvm_cma_reserve: reserving 6553 MiB for global area cma: Failed to reserve 6553 MiB That makes it impossible to start KVM guests using the hash MMU with more than 2G of memory, because the VM is unable to allocate a large enough region for the hash page table, eg: $ qemu-system-ppc64 -enable-kvm -M pseries -m 4G ... qemu-system-ppc64: Failed to allocate KVM HPT of order 25: Cannot allocate memory Aneesh pointed out that this happens because when kvm_cma_reserve() is called, pageblock_order has not been initialised yet, and is still zero, causing the checks in cma_init_reserved_mem() against CMA_MIN_ALIGNMENT_PAGES to fail. Fix it by moving the call to kvm_cma_reserve() after initmem_init(). The pageblock_order is initialised in sparse_init() which is called from initmem_init(). Also move the hugetlb CMA reservation. Fixes: 11ac3e87ce09 ("mm: cma: use pageblock_order as the single alignment") Reviewed-by: Aneesh Kumar K.V Reviewed-by: Zi Yan Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220616120033.1976732-1-mpe@ellerman.id.au --- arch/powerpc/kernel/setup-common.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c index eb0077b..1a02629 100644 --- a/arch/powerpc/kernel/setup-common.c +++ b/arch/powerpc/kernel/setup-common.c @@ -935,12 +935,6 @@ void __init setup_arch(char **cmdline_p) /* Print various info about the machine that has been gathered so far. */ print_system_info(); - /* Reserve large chunks of memory for use by CMA for KVM. */ - kvm_cma_reserve(); - - /* Reserve large chunks of memory for us by CMA for hugetlb */ - gigantic_hugetlb_cma_reserve(); - klp_init_thread_info(&init_task); setup_initial_init_mm(_stext, _etext, _edata, _end); @@ -955,6 +949,13 @@ void __init setup_arch(char **cmdline_p) initmem_init(); + /* + * Reserve large chunks of memory for use by CMA for KVM and hugetlb. These must + * be called after initmem_init(), so that pageblock_order is initialised. + */ + kvm_cma_reserve(); + gigantic_hugetlb_cma_reserve(); + early_memtest(min_low_pfn << PAGE_SHIFT, max_low_pfn << PAGE_SHIFT); if (ppc_md.setup_arch) -- 2.7.4