Displaying 6 results from an estimated 6 matches for "__remove_mapping".
2019 Mar 07
0
[RFC PATCH V2 5/5] vhost: access vq metadata through kernel virtual address
...ith the speculative pagecache lookups but it cannot
give false negatives. We use those checks to know when a page is
pinned by GUP, for example, where we cannot merge KSM pages with gup
pins etc... However what if the elevated refcount wasn't there when
try_to_free_buffers run and is there when __remove_mapping runs?
What I mean is that it sounds easy to forbid try_to_free_buffers for
the long term pins, but that still won't prevent the same exact issue
for a transient pin (except the window to trigger it will be much smaller).
I basically don't see how long term GUP pins breaks stuff in ext4
wh...
2019 Mar 07
3
[RFC PATCH V2 5/5] vhost: access vq metadata through kernel virtual address
On Thu, Mar 07, 2019 at 10:45:57AM +0800, Jason Wang wrote:
>
> On 2019/3/7 ??12:31, Michael S. Tsirkin wrote:
> > > +static void vhost_set_vmap_dirty(struct vhost_vmap *used)
> > > +{
> > > + int i;
> > > +
> > > + for (i = 0; i < used->npages; i++)
> > > + set_page_dirty_lock(used->pages[i]);
> > This seems to rely on
2019 Mar 07
3
[RFC PATCH V2 5/5] vhost: access vq metadata through kernel virtual address
On Thu, Mar 07, 2019 at 10:45:57AM +0800, Jason Wang wrote:
>
> On 2019/3/7 ??12:31, Michael S. Tsirkin wrote:
> > > +static void vhost_set_vmap_dirty(struct vhost_vmap *used)
> > > +{
> > > + int i;
> > > +
> > > + for (i = 0; i < used->npages; i++)
> > > + set_page_dirty_lock(used->pages[i]);
> > This seems to rely on
2019 Mar 07
1
[RFC PATCH V2 5/5] vhost: access vq metadata through kernel virtual address
On Thu, Mar 07, 2019 at 10:34:39AM -0500, Michael S. Tsirkin wrote:
> On Thu, Mar 07, 2019 at 10:45:57AM +0800, Jason Wang wrote:
> >
> > On 2019/3/7 ??12:31, Michael S. Tsirkin wrote:
> > > > +static void vhost_set_vmap_dirty(struct vhost_vmap *used)
> > > > +{
> > > > + int i;
> > > > +
> > > > + for (i = 0; i <
2019 Mar 07
3
[RFC PATCH V2 5/5] vhost: access vq metadata through kernel virtual address
...pagecache lookups but it cannot
> give false negatives. We use those checks to know when a page is
> pinned by GUP, for example, where we cannot merge KSM pages with gup
> pins etc... However what if the elevated refcount wasn't there when
> try_to_free_buffers run and is there when __remove_mapping runs?
>
> What I mean is that it sounds easy to forbid try_to_free_buffers for
> the long term pins, but that still won't prevent the same exact issue
> for a transient pin (except the window to trigger it will be much smaller).
I think here you do not want to go down the same pat...
2019 Mar 07
3
[RFC PATCH V2 5/5] vhost: access vq metadata through kernel virtual address
...pagecache lookups but it cannot
> give false negatives. We use those checks to know when a page is
> pinned by GUP, for example, where we cannot merge KSM pages with gup
> pins etc... However what if the elevated refcount wasn't there when
> try_to_free_buffers run and is there when __remove_mapping runs?
>
> What I mean is that it sounds easy to forbid try_to_free_buffers for
> the long term pins, but that still won't prevent the same exact issue
> for a transient pin (except the window to trigger it will be much smaller).
I think here you do not want to go down the same pat...