On 21/04/14 15:25, Oleg Nesterov wrote: > async_pf_execute() has no reasons to adopt apf->mm, gup(current, mm) > should work just fine even if current has another or NULL ->mm. > > Recently kvm_async_page_present_sync() was added insedie the "use_mm" > section, but it seems that it doesn't need current->mm too. > > Signed-off-by: Oleg Nesterov <o...@redhat.com>
Indeed, use/unuse_mm should only be necessary for copy_to/from_user etc. This is fine for s390, but it seems that x86 kvm_arch_async_page_not_present might call apf_put_user which might call copy_to_user, so this is not ok, I guess. > --- > virt/kvm/async_pf.c | 2 -- > 1 files changed, 0 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c > index 10df100..0ced4f3 100644 > --- a/virt/kvm/async_pf.c > +++ b/virt/kvm/async_pf.c > @@ -80,12 +80,10 @@ static void async_pf_execute(struct work_struct *work) > > might_sleep(); > > - use_mm(mm); > down_read(&mm->mmap_sem); > get_user_pages(current, mm, addr, 1, 1, 0, NULL, NULL); > up_read(&mm->mmap_sem); > kvm_async_page_present_sync(vcpu, apf); > - unuse_mm(mm); > > spin_lock(&vcpu->async_pf.lock); > list_add_tail(&apf->link, &vcpu->async_pf.done); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
