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? -- Cheers, Jia _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
