diff options
| author |   David Hildenbrand <david@redhat.com> | 2024-05-08 20:29:46 +0200 |
|---|---|---|
| committer |   Alexander Gordeev <agordeev@linux.ibm.com> | 2024-06-05 17:17:23 +0200 |
| commit | 3f29f6537f54d74e64bac0a390fb2e26da25800d (patch) | |
| tree | 2cc5f9931dc7b8fc59c4d8800b3b1ce59ff2aa2f | |
| parent | Linux 6.10-rc2 (diff) | |
| download | wireguard-linux-3f29f6537f54d74e64bac0a390fb2e26da25800d.tar.xz wireguard-linux-3f29f6537f54d74e64bac0a390fb2e26da25800d.zip | |
s390/uv: Don't call folio_wait_writeback() without a folio reference
folio_wait_writeback() requires that no spinlocks are held and that
a folio reference is held, as documented. After we dropped the PTL, the
folio could get freed concurrently. So grab a temporary reference.
Fixes: 214d9bbcd3a6 ("s390/mm: provide memory management functions for protected KVM guests")
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20240508182955.358628-2-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
| -rw-r--r-- | arch/s390/kernel/uv.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c index 265fea37e030..016993e9eb72 100644 --- a/arch/s390/kernel/uv.c +++ b/arch/s390/kernel/uv.c @@ -318,6 +318,13 @@ again: rc = make_folio_secure(folio, uvcb); folio_unlock(folio); } + + /* + * Once we drop the PTL, the folio may get unmapped and + * freed immediately. We need a temporary reference. + */ + if (rc == -EAGAIN) + folio_get(folio); } unlock: pte_unmap_unlock(ptep, ptelock); @@ -330,6 +337,7 @@ out: * completion, this is just a useless check, but it is safe. */ folio_wait_writeback(folio); + folio_put(folio); } else if (rc == -EBUSY) { /* * If we have tried a local drain and the folio refcount |