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| author |   David Hildenbrand <david@redhat.com> | 2019-03-14 17:02:56 +0100 |
|---|---|---|
| committer |   Juergen Gross <jgross@suse.com> | 2019-03-15 15:35:35 +0100 |
| commit | 0266def913771e718fd0c998eecb072e0685e2c9 (patch) | |
| tree | 1d503c09f9630e1d17424c44b502c0d0ea4b2a8d | |
| parent | Merge branch 'akpm' (patches from Andrew) (diff) | |
| download | linux-dev-0266def913771e718fd0c998eecb072e0685e2c9.tar.xz linux-dev-0266def913771e718fd0c998eecb072e0685e2c9.zip | |
xen/balloon: Fix mapping PG_offline pages to user space
The XEN balloon driver - in contrast to other balloon drivers - allows
to map some inflated pages to user space. Such pages are allocated via
alloc_xenballooned_pages() and freed via free_xenballooned_pages().
The pfn space of these allocated pages is used to map other things
by the hypervisor using hypercalls.
Pages marked with PG_offline must never be mapped to user space (as
this page type uses the mapcount field of struct pages).
So what we can do is, clear/set PG_offline when allocating/freeing an
inflated pages. This way, most inflated pages can be excluded by
dumping tools and the "reused for other purpose" balloon pages are
correctly not marked as PG_offline.
Fixes: 77c4adf6a6df (xen/balloon: mark inflated pages PG_offline)
Reported-by: Julien Grall <julien.grall@arm.com>
Tested-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
| -rw-r--r-- | drivers/xen/balloon.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 39b229f9e256..d37dd5bb7a8f 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -604,6 +604,7 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages) while (pgno < nr_pages) { page = balloon_retrieve(true); if (page) { + __ClearPageOffline(page); pages[pgno++] = page; #ifdef CONFIG_XEN_HAVE_PVMMU /* @@ -645,8 +646,10 @@ void free_xenballooned_pages(int nr_pages, struct page **pages) mutex_lock(&balloon_mutex); for (i = 0; i < nr_pages; i++) { - if (pages[i]) + if (pages[i]) { + __SetPageOffline(pages[i]); balloon_append(pages[i]); + } } balloon_stats.target_unpopulated -= nr_pages; |