From 7a2653612bb6f18fb236c5b0c4d28f7b459bf7c2 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 27 Mar 2020 08:06:42 +0100 Subject: [PATCH] s390/gmap: return proper error code on ksm unsharing If a signal is pending we might return -ENOMEM instead of -EINTR. We should propagate the proper error during KSM unsharing. unmerge_ksm_pages returns -ERESTARTSYS on signal_pending. This gets translated by entry.S to -EINTR. It is important to get this error code so that userspace can retry. To make this clearer we also add -EINTR to the documentation of the PV_ENABLE call, which calls unmerge_ksm_pages. Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages") Reviewed-by: Janosch Frank Reported-by: Marc Hartmayer Tested-by: Marc Hartmayer Reviewed-by: David Hildenbrand Reviewed-by: Cornelia Huck Signed-off-by: Christian Borntraeger --- Documentation/virt/kvm/api.rst | 6 ++++++ arch/s390/mm/gmap.c | 9 +++++---- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index bae90f3..2edb28b 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -4677,6 +4677,12 @@ KVM_PV_ENABLE command has succeeded, any CPU added via hotplug will become protected during its creation as well. + Errors: + + ===== ============================= + EINTR an unmasked signal is pending + ===== ============================= + KVM_PV_DISABLE Deregister the VM from the Ultravisor and reclaim the memory that diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index 03c8998..2fbece4 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -2552,12 +2552,13 @@ int gmap_mark_unmergeable(void) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma; + int ret; for (vma = mm->mmap; vma; vma = vma->vm_next) { - if (ksm_madvise(vma, vma->vm_start, vma->vm_end, - MADV_UNMERGEABLE, &vma->vm_flags)) { - return -ENOMEM; - } + ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, + MADV_UNMERGEABLE, &vma->vm_flags); + if (ret) + return ret; } mm->def_flags &= ~VM_MERGEABLE; return 0; -- 2.7.4