On 11/14/2011 11:23 AM, Takuya Yoshikawa wrote: > Needed for the next patch which uses this number to decide how to write > protect a slot. > > /* If nothing is dirty, don't bother messing with page tables. */ > - if (is_dirty) { > + if (memslot->nr_dirty_pages) { > struct kvm_memslots *slots, *old_slots; > unsigned long *dirty_bitmap; > > @@ -3504,6 +3500,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, > goto out; > memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots)); > slots->memslots[log->slot].dirty_bitmap = dirty_bitmap; > + slots->memslots[log->slot].nr_dirty_pages = 0; > slots->generation++; > > #endif /* !CONFIG_S390 */ > @@ -1491,7 +1492,8 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot, > if (memslot && memslot->dirty_bitmap) { > unsigned long rel_gfn = gfn - memslot->base_gfn; > > - __set_bit_le(rel_gfn, memslot->dirty_bitmap); > + if (!__test_and_set_bit_le(rel_gfn, memslot->dirty_bitmap)) > + memslot->nr_dirty_pages++; > } > } > The two assignments to ->nr_dirty_pages can race, no? Nothing protects it. btw mark_page_dirty() itself seems to assume mmu_lock protection that doesn't exist. Marcelo? -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html