search for: scan_movable_pag

...hat can be skipped when offlining), but bail out on + * definitely unmovable pages. + * + * Returns: + * 0 in case a movable page is found and movable_pfn was updated. + * -ENOENT in case no movable page was found. + * -EBUSY in case a definitely unmovable page was found. */ -static unsigned long scan_movable_pages(unsigned long start, unsigned long end) +static int scan_movable_pages(unsigned long start, unsigned long end, + unsigned long *movable_pfn) { unsigned long pfn; @@ -1237,18 +1243,30 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) continue; p...

...hat can be skipped when offlining), but bail out on + * definitely unmovable pages. + * + * Returns: + * 0 in case a movable page is found and movable_pfn was updated. + * -ENOENT in case no movable page was found. + * -EBUSY in case a definitely unmovable page was found. */ -static unsigned long scan_movable_pages(unsigned long start, unsigned long end) +static int scan_movable_pages(unsigned long start, unsigned long end, + unsigned long *movable_pfn) { unsigned long pfn; @@ -1237,18 +1243,30 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) continue; p...

...hat can be skipped when offlining), but bail out on + * definitely unmovable pages. + * + * Returns: + * 0 in case a movable page is found and movable_pfn was updated. + * -ENOENT in case no movable page was found. + * -EBUSY in case a definitely unmovable page was found. */ -static unsigned long scan_movable_pages(unsigned long start, unsigned long end) +static int scan_movable_pages(unsigned long start, unsigned long end, + unsigned long *movable_pfn) { unsigned long pfn; @@ -1167,18 +1173,30 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) continue; p...

...bail out on > + * definitely unmovable pages. > + * > + * Returns: > + * 0 in case a movable page is found and movable_pfn was updated. > + * -ENOENT in case no movable page was found. > + * -EBUSY in case a definitely unmovable page was found. > */ > -static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > +static int scan_movable_pages(unsigned long start, unsigned long end, > + unsigned long *movable_pfn) > { > unsigned long pfn; > > @@ -1237,18 +1243,30 @@ static unsigned long scan_movable_pages(unsigned long start, unsigne...

On Wed 23-10-19 12:03:51, David Hildenbrand wrote: > >Do you see any downsides? > > The only downside I see is that we get more false negatives on > has_unmovable_pages(), eventually resulting in the offlining stage after > isolation to loop forever (as some PageOffline() pages are not movable > (especially, XEN balloon, HyperV balloon), there won't be progress). >

On Wed 23-10-19 12:03:51, David Hildenbrand wrote: > >Do you see any downsides? > > The only downside I see is that we get more false negatives on > has_unmovable_pages(), eventually resulting in the offlining stage after > isolation to loop forever (as some PageOffline() pages are not movable > (especially, XEN balloon, HyperV balloon), there won't be progress). >

...bail out on > + * definitely unmovable pages. > + * > + * Returns: > + * 0 in case a movable page is found and movable_pfn was updated. > + * -ENOENT in case no movable page was found. > + * -EBUSY in case a definitely unmovable page was found. > */ > -static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > +static int scan_movable_pages(unsigned long start, unsigned long end, > + unsigned long *movable_pfn) > { > unsigned long pfn; > > @@ -1237,18 +1243,30 @@ static unsigned long scan_movable_pages(unsigned long start, unsigne...

...PG_offline > -> PF_offline must not be cleared so dumping tools will not touch > these pages. There is a time where pages are !PageBuddy() and > !PageOffline(). Well, this is fully under control of the driver, no? Reference count shouldn't play any role here AFAIU. > 3) scan_movable_pages() ... > > 4a) Memory offlining succeeded: memory_notify(MEM_OFFLINE, &arg); > > Perfect, it worked. Sections are offline. > > 4b) Memory offlining failed > > undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); > memory_notify(MEM_CANCEL_OFFLINE...

...PG_offline > -> PF_offline must not be cleared so dumping tools will not touch > these pages. There is a time where pages are !PageBuddy() and > !PageOffline(). Well, this is fully under control of the driver, no? Reference count shouldn't play any role here AFAIU. > 3) scan_movable_pages() ... > > 4a) Memory offlining succeeded: memory_notify(MEM_OFFLINE, &arg); > > Perfect, it worked. Sections are offline. > > 4b) Memory offlining failed > > undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); > memory_notify(MEM_CANCEL_OFFLINE...

On Wed 16-10-19 16:14:52, David Hildenbrand wrote: > On 16.10.19 16:03, Michal Hocko wrote: [...] > > But why cannot you keep the reference count at 1 (do get_page when > > offlining the page)? In other words as long as the driver knows the page > > has been returned to the host then it has ref count at 1. Once the page > > is returned to the guest for whatever reason it

On Wed 16-10-19 16:14:52, David Hildenbrand wrote: > On 16.10.19 16:03, Michal Hocko wrote: [...] > > But why cannot you keep the reference count at 1 (do get_page when > > offlining the page)? In other words as long as the driver knows the page > > has been returned to the host then it has ref count at 1. Once the page > > is returned to the guest for whatever reason it

...that. > > 2) memory_notify(MEM_GOING_OFFLINE, &arg); > -> Here, we could release all pages to the buddy, clearing PG_offline > -> BAD, PF_offline must not be cleared so dumping tools will not touch > these pages. I don't see a way to hack around that. > > 3) scan_movable_pages() ... > > 4a) memory_notify(MEM_OFFLINE, &arg); > > Perfect, it worked. Sections are offline. > > 4b) undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); > memory_notify(MEM_CANCEL_OFFLINE, &arg); > > -> Offlining failed for whatever reason....

...that. > > 2) memory_notify(MEM_GOING_OFFLINE, &arg); > -> Here, we could release all pages to the buddy, clearing PG_offline > -> BAD, PF_offline must not be cleared so dumping tools will not touch > these pages. I don't see a way to hack around that. > > 3) scan_movable_pages() ... > > 4a) memory_notify(MEM_OFFLINE, &arg); > > Perfect, it worked. Sections are offline. > > 4b) undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); > memory_notify(MEM_CANCEL_OFFLINE, &arg); > > -> Offlining failed for whatever reason....

...t right away. We could hack around that. 2) memory_notify(MEM_GOING_OFFLINE, &arg); -> Here, we could release all pages to the buddy, clearing PG_offline -> BAD, PF_offline must not be cleared so dumping tools will not touch these pages. I don't see a way to hack around that. 3) scan_movable_pages() ... 4a) memory_notify(MEM_OFFLINE, &arg); Perfect, it worked. Sections are offline. 4b) undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); memory_notify(MEM_CANCEL_OFFLINE, &arg); -> Offlining failed for whatever reason. -> Pages are in the buddy, but we alread...

This series is based on latest linux-next. The patches are located at: https://github.com/davidhildenbrand/linux.git virtio-mem-v2 I now have acks for all !virtio-mem changes. I'll be happy to get review feedback, testing reports, etc. for the virtio-mem changes. If there are no further comments, I guess this is good to go as a v1 soon. The basic idea of virtio-mem is to provide a

...g to free page to the allocator then it would have to claim the page back and so it is usable again. If it cannot free it then it would simply set the reference count to 0. It can even keep the PG_offline if necessary although I have to admit I am not really sure it is necessary. > > > 3) scan_movable_pages() ... > > Please note that when we don't put the pages back to the buddy and don't > implement something like I have in this patch, we'll loop/fail here. > Especially if we have pages with PG_offline + refcount >= 1 . You should have your reference count 0 at this sta...

...g to free page to the allocator then it would have to claim the page back and so it is usable again. If it cannot free it then it would simply set the reference count to 0. It can even keep the PG_offline if necessary although I have to admit I am not really sure it is necessary. > > > 3) scan_movable_pages() ... > > Please note that when we don't put the pages back to the buddy and don't > implement something like I have in this patch, we'll loop/fail here. > Especially if we have pages with PG_offline + refcount >= 1 . You should have your reference count 0 at this sta...

This series is based on latest linux-next. The patches are located at: https://github.com/davidhildenbrand/linux.git virtio-mem-v3 Patch #1 - #10 where contained in v2 and only contain minor modifications (mostly smaller fixes). The remaining patches are new and contain smaller optimizations. Details about virtio-mem can be found in the cover letter of v2 [1]. A basic QEMU implementation was

This series is based on latest linux-next. The patches are located at: https://github.com/davidhildenbrand/linux.git virtio-mem-v3 Patch #1 - #10 where contained in v2 and only contain minor modifications (mostly smaller fixes). The remaining patches are new and contain smaller optimizations. Details about virtio-mem can be found in the cover letter of v2 [1]. A basic QEMU implementation was

...memory_notify(MEM_GOING_OFFLINE, &arg); >> -> Here, we could release all pages to the buddy, clearing PG_offline >> -> BAD, PF_offline must not be cleared so dumping tools will not touch >> these pages. I don't see a way to hack around that. >> >> 3) scan_movable_pages() ... >> >> 4a) memory_notify(MEM_OFFLINE, &arg); >> >> Perfect, it worked. Sections are offline. >> >> 4b) undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); >> memory_notify(MEM_CANCEL_OFFLINE, &arg); >> >> -> Offl...