Support for unaccepted memory was added recently, refer commit
dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby a virtual
machine may need to accept memory before it can be used.

Do not try to access unaccepted memory because it can cause the guest to
fail.

For /proc/kcore, which is read-only and does not support mmap, this means a
read of unaccepted memory will return zeros.

Signed-off-by: Adrian Hunter <adrian.hun...@intel.com>
---
 fs/proc/kcore.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)


Changes in V2:

          Change patch subject and commit message
          Do not open code pfn_is_unaccepted_memory()


diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 23fc24d16b31..6422e569b080 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -546,7 +546,8 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct 
iov_iter *iter)
                         * and explicitly excluded physical ranges.
                         */
                        if (!page || PageOffline(page) ||
-                           is_page_hwpoison(page) || !pfn_is_ram(pfn)) {
+                           is_page_hwpoison(page) || !pfn_is_ram(pfn) ||
+                           pfn_is_unaccepted_memory(pfn)) {
                                if (iov_iter_zero(tsz, iter) != tsz) {
                                        ret = -EFAULT;
                                        goto out;
-- 
2.34.1


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