| Message ID | 20221222205511.675832-1-david@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | mm/hugetlb: uffd-wp fixes for hugetlb_change_protection() | expand |
On Thu, Dec 22, 2022 at 09:55:09PM +0100, David Hildenbrand wrote: > Playing with virtio-mem and background snapshots (using uffd-wp) on > hugetlb in QEMU, I managed to trigger a VM_BUG_ON(). Looking into the > details, hugetlb_change_protection() seems to not handle uffd-wp correctly > in all cases. > > Patch #1 fixes my test case. I don't have reproducers for patch #2, as > it requires running into migration entries. > > I did not yet check in detail yet if !hugetlb code requires similar care. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Mike Kravetz <mike.kravetz@oracle.com> > Cc: Peter Xu <peterx@redhat.com> > Cc: Muchun Song <muchun.song@linux.dev> > Cc: Miaohe Lin <linmiaohe@huawei.com> > > David Hildenbrand (2): > mm/hugetlb: fix PTE marker handling in hugetlb_change_protection() > mm/hugetlb: fix uffd-wp handling for migration entries in > hugetlb_change_protection() Reviewed-by: Peter Xu <peterx@redhat.com> Thanks, David.
On Thu, Dec 22, 2022 at 04:17:22PM -0500, Peter Xu wrote: > On Thu, Dec 22, 2022 at 09:55:09PM +0100, David Hildenbrand wrote: > > Playing with virtio-mem and background snapshots (using uffd-wp) on > > hugetlb in QEMU, I managed to trigger a VM_BUG_ON(). Looking into the > > details, hugetlb_change_protection() seems to not handle uffd-wp correctly > > in all cases. > > > > Patch #1 fixes my test case. I don't have reproducers for patch #2, as > > it requires running into migration entries. > > > > I did not yet check in detail yet if !hugetlb code requires similar care. Ah I should have left a message here but I forgot - afaict shmem is all fine. > > > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Mike Kravetz <mike.kravetz@oracle.com> > > Cc: Peter Xu <peterx@redhat.com> > > Cc: Muchun Song <muchun.song@linux.dev> > > Cc: Miaohe Lin <linmiaohe@huawei.com> > > > > David Hildenbrand (2): > > mm/hugetlb: fix PTE marker handling in hugetlb_change_protection() > > mm/hugetlb: fix uffd-wp handling for migration entries in > > hugetlb_change_protection() > > Reviewed-by: Peter Xu <peterx@redhat.com> > > Thanks, David. > > -- > Peter Xu
Playing with virtio-mem and background snapshots (using uffd-wp) on hugetlb in QEMU, I managed to trigger a VM_BUG_ON(). Looking into the details, hugetlb_change_protection() seems to not handle uffd-wp correctly in all cases. Patch #1 fixes my test case. I don't have reproducers for patch #2, as it requires running into migration entries. I did not yet check in detail yet if !hugetlb code requires similar care. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Miaohe Lin <linmiaohe@huawei.com> David Hildenbrand (2): mm/hugetlb: fix PTE marker handling in hugetlb_change_protection() mm/hugetlb: fix uffd-wp handling for migration entries in hugetlb_change_protection() mm/hugetlb.c | 38 ++++++++++++++++---------------------- 1 file changed, 16 insertions(+), 22 deletions(-)