From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org,
David Hildenbrand <david@redhat.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Matthew Wilcox <willy@infradead.org>,
Thomas Huth <thuth@redhat.com>
Subject: [PATCH v3 01/10] s390/uv: don't call folio_wait_writeback() without a folio reference
Date: Wed, 8 May 2024 20:29:46 +0200 [thread overview]
Message-ID: <20240508182955.358628-2-david@redhat.com> (raw)
In-Reply-To: <20240508182955.358628-1-david@redhat.com>
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>
---
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 265fea37e030..016993e9eb72 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -318,6 +318,13 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
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 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
* 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
--
2.45.0
next prev parent reply other threads:[~2024-05-08 18:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-08 18:29 [PATCH v3 00/10] s390: PG_arch_1+folio cleanups for uv+hugetlb David Hildenbrand
2024-05-08 18:29 ` David Hildenbrand [this message]
2024-05-08 18:29 ` [PATCH v3 02/10] s390/uv: gmap_make_secure() cleanups for further changes David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 03/10] s390/uv: split large folios in gmap_make_secure() David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 04/10] s390/uv: convert PG_arch_1 users to only work on small folios David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 05/10] s390/uv: update PG_arch_1 comment David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 06/10] s390/uv: make uv_convert_from_secure() a static function David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 07/10] s390/uv: convert uv_destroy_owned_page() to uv_destroy_(folio|pte)() David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 08/10] s390/uv: convert uv_convert_owned_from_secure() to uv_convert_from_secure_(folio|pte)() David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 09/10] s390/uv: implement HAVE_ARCH_MAKE_FOLIO_ACCESSIBLE David Hildenbrand
2024-05-08 18:29 ` [PATCH v3 10/10] s390/hugetlb: convert PG_arch_1 code to work on folio->flags David Hildenbrand
2024-05-09 15:04 ` [PATCH v3 00/10] s390: PG_arch_1+folio cleanups for uv+hugetlb Heiko Carstens
2024-05-09 17:26 ` David Hildenbrand
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