iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

s390/uv: Don't call folio_wait_writeback() without a folio reference

Browse Source 
[ Upstream commit 3f29f6537f54d74e64bac0a390fb2e26da25800d ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
David Hildenbrand 2024-05-08 20:29:46 +02:00 committed by Greg Kroah-Hartman
parent cd5df00391
commit 1a1eb2f3fc
1 changed files with 8 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/s390/kernel/uv.c
View File

@ -299,6 +299,13 @@ 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);
@ -311,6 +318,7 @@ 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