| Message ID | 20220628080228.1508847-1-aik@ozlabs.ru |
|---|---|
| State | New |
| Headers | show |
| Series | [kernel] KVM: PPC: Do not warn when userspace asked for too big TCE table | expand |
On Tue, 28 Jun 2022 18:02:28 +1000, Alexey Kardashevskiy wrote: > KVM manages emulated TCE tables for guest LIOBNs by a two level table > which maps up to 128TiB with 16MB IOMMU pages (enabled in QEMU by default) > and MAX_ORDER=11 (the kernel's default). Note that the last level of > the table is allocated when actual TCE is updated. > > However these tables are created via ioctl() on kvmfd and the userspace > can trigger WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp) in mm/page_alloc.c > and flood dmesg. > > [...] Applied to powerpc/topic/ppc-kvm. [1/1] KVM: PPC: Do not warn when userspace asked for too big TCE table https://git.kernel.org/powerpc/c/4dee21e0f2520f5032b0abce0ecae593a71bd19d cheers
diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index d6589c4fe889..40864373ef87 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -307,7 +307,7 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, return ret; ret = -ENOMEM; - stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL); + stt = kzalloc(struct_size(stt, pages, npages), GFP_KERNEL | __GFP_NOWARN); if (!stt) goto fail_acct;
KVM manages emulated TCE tables for guest LIOBNs by a two level table which maps up to 128TiB with 16MB IOMMU pages (enabled in QEMU by default) and MAX_ORDER=11 (the kernel's default). Note that the last level of the table is allocated when actual TCE is updated. However these tables are created via ioctl() on kvmfd and the userspace can trigger WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp) in mm/page_alloc.c and flood dmesg. This adds __GFP_NOWARN. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- We could probably switch to vmalloc() to allow even bigger emulated tables which we do not really want the userspace to create though. --- arch/powerpc/kvm/book3s_64_vio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)