Re: [PATCH RFC 10/24] userfaultfd: wp: add WP pagetable tracking to x86

2019-01-24 Thread Peter Xu
On Thu, Jan 24, 2019 at 10:40:50AM -0500, Jerome Glisse wrote: > On Thu, Jan 24, 2019 at 01:16:16PM +0800, Peter Xu wrote: > > On Mon, Jan 21, 2019 at 10:09:38AM -0500, Jerome Glisse wrote: > > > On Mon, Jan 21, 2019 at 03:57:08PM +0800, Peter Xu wrote: > > > > From: Andrea Arcangeli > > > > > >

Re: [PATCH RFC 10/24] userfaultfd: wp: add WP pagetable tracking to x86

2019-01-24 Thread Jerome Glisse
On Thu, Jan 24, 2019 at 01:16:16PM +0800, Peter Xu wrote: > On Mon, Jan 21, 2019 at 10:09:38AM -0500, Jerome Glisse wrote: > > On Mon, Jan 21, 2019 at 03:57:08PM +0800, Peter Xu wrote: > > > From: Andrea Arcangeli > > > > > > Accurate userfaultfd WP tracking is possible by tracking exactly which

Re: [PATCH RFC 10/24] userfaultfd: wp: add WP pagetable tracking to x86

2019-01-23 Thread Peter Xu
On Mon, Jan 21, 2019 at 10:09:38AM -0500, Jerome Glisse wrote: > On Mon, Jan 21, 2019 at 03:57:08PM +0800, Peter Xu wrote: > > From: Andrea Arcangeli > > > > Accurate userfaultfd WP tracking is possible by tracking exactly which > > virtual memory ranges were writeprotected by userland. We can't

Re: [PATCH RFC 10/24] userfaultfd: wp: add WP pagetable tracking to x86

2019-01-21 Thread Jerome Glisse
On Mon, Jan 21, 2019 at 03:57:08PM +0800, Peter Xu wrote: > From: Andrea Arcangeli > > Accurate userfaultfd WP tracking is possible by tracking exactly which > virtual memory ranges were writeprotected by userland. We can't relay > only on the RW bit of the mapped pagetable because that

[PATCH RFC 10/24] userfaultfd: wp: add WP pagetable tracking to x86

2019-01-20 Thread Peter Xu
From: Andrea Arcangeli Accurate userfaultfd WP tracking is possible by tracking exactly which virtual memory ranges were writeprotected by userland. We can't relay only on the RW bit of the mapped pagetable because that information is destroyed by fork() or KSM or swap. If we were to relay on