| Message ID | 20240404163642.1125529-2-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | s390: page_mapcount(), page_has_private() and PG_arch_1 | expand |
On Thu, 4 Apr 2024 18:36:38 +0200 David Hildenbrand <david@redhat.com> wrote: > wait_on_page_writeback() requires that no spinlocks are held and that > a page reference is held, as documented for folio_wait_writeback(). After oops > we dropped the PTL, the page could get freed concurrently. So grab a > temporary reference. > > Fixes: 214d9bbcd3a6 ("s390/mm: provide memory management functions for protected KVM guests") > Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> > --- > arch/s390/kernel/uv.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c > index fc07bc39e698..7401838b960b 100644 > --- a/arch/s390/kernel/uv.c > +++ b/arch/s390/kernel/uv.c > @@ -314,6 +314,13 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) > rc = make_page_secure(page, uvcb); > unlock_page(page); > } > + > + /* > + * Once we drop the PTL, the page may get unmapped and > + * freed immediately. We need a temporary reference. > + */ > + if (rc == -EAGAIN) > + get_page(page); > } > pte_unmap_unlock(ptep, ptelock); > out: > @@ -325,6 +332,7 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) > * completion, this is just a useless check, but it is safe. > */ > wait_on_page_writeback(page); > + put_page(page); > } else if (rc == -EBUSY) { > /* > * If we have tried a local drain and the page refcount
On 10.04.24 19:21, Claudio Imbrenda wrote:
> Reviewed-by: Claudio Imbrenda<imbrenda@linux.ibm.com>
Thanks! I'll rebase this series on top of the s390/features tree for
now, where Willy's cleanups already reside.
If maintainers want to have that fix first, I can send it out with
Willy's patches rebased on this fix. Whatever people prefer.
On Thu, Apr 11, 2024 at 10:24:23AM +0200, David Hildenbrand wrote: > Thanks! I'll rebase this series on top of the s390/features tree for now, > where Willy's cleanups already reside. Yes, rebase it on to of s390/features, please. > If maintainers want to have that fix first, I can send it out with Willy's > patches rebased on this fix. Whatever people prefer. Many thanks! > -- > Cheers, > > David / dhildenb
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c index fc07bc39e698..7401838b960b 100644 --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -314,6 +314,13 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) rc = make_page_secure(page, uvcb); unlock_page(page); } + + /* + * Once we drop the PTL, the page may get unmapped and + * freed immediately. We need a temporary reference. + */ + if (rc == -EAGAIN) + get_page(page); } pte_unmap_unlock(ptep, ptelock); out: @@ -325,6 +332,7 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb) * completion, this is just a useless check, but it is safe. */ wait_on_page_writeback(page); + put_page(page); } else if (rc == -EBUSY) { /* * If we have tried a local drain and the page refcount
wait_on_page_writeback() requires that no spinlocks are held and that a page reference is held, as documented for folio_wait_writeback(). After we dropped the PTL, the page could get freed concurrently. So grab a temporary reference. Fixes: 214d9bbcd3a6 ("s390/mm: provide memory management functions for protected KVM guests") Signed-off-by: David Hildenbrand <david@redhat.com> --- arch/s390/kernel/uv.c | 8 ++++++++ 1 file changed, 8 insertions(+)