On Fri, May 18, 2018 at 09:04:40PM +0800, Jia He wrote: > > > On 5/18/2018 5:48 PM, Marc Zyngier Wrote: > > On 18/05/18 10:27, Jia He wrote: > >> If it passes addr=0x202920000,size=0xfe00 to unmap_stage2_range-> > >> ...->unmap_stage2_ptes, unmap_stage2_ptes will get addr=0x202920000, > >> end=0x20292fe00. After first while loop addr=0x202930000, end=0x20292fe00, > >> then addr!=end. Thus it will touch another pages by put_pages() in the > >> 2nd loop. > >> > >> This patch fixes it by hardening the break condition of while loop. > >> > >> Signed-off-by: jia.he@xxxxxxxxxxxxxxxx > >> --- > >> v2: newly added > >> > >> virt/kvm/arm/mmu.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c > >> index 8dac311..45cd040 100644 > >> --- a/virt/kvm/arm/mmu.c > >> +++ b/virt/kvm/arm/mmu.c > >> @@ -217,7 +217,7 @@ static void unmap_stage2_ptes(struct kvm *kvm, pmd_t *pmd, > >> > >> put_page(virt_to_page(pte)); > >> } > >> - } while (pte++, addr += PAGE_SIZE, addr != end); > >> + } while (pte++, addr += PAGE_SIZE, addr < end); > >> > >> if (stage2_pte_table_empty(start_pte)) > >> clear_stage2_pmd_entry(kvm, pmd, start_addr); > >> > > > > I don't think this change is the right thing to do. You get that failure > > because you're being passed a size that is not a multiple of PAGE_SIZE. > > That's the mistake. > > > > You should ensure that this never happens, rather than changing the page > > table walkers (which are consistent with the way this kind of code is > > written in other places of the kernel). As you mentioned in your first > > patch, the real issue is that KSM is broken, and this is what should be > > fixed. > > > Got it, thanks > Should I resend the patch 1/2 without any changes after droping patch 2/2? > That's fine if you trim the commit message to make it look nicer. Also, in the future, please include a cover letter if you send more than one patch to the list. Thanks, -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
