Re: [PATCH V2 2/2] proc/kcore: Do not try to access unaccepted memory

2023-09-12 Thread David Hildenbrand 

On 11.09.23 13:21, Adrian Hunter wrote:

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 
---
  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;


Reviewed-by: David Hildenbrand 

--
Cheers,

David / dhildenb


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[PATCH V2 2/2] proc/kcore: Do not try to access unaccepted memory

2023-09-11 Thread Adrian Hunter 
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 
---
 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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