Make __get_user_pages return -EHWPOISON for HWPOISON page only if
FOLL_HWPOISON is specified. With this patch, the interested callers
can distinguish HWPOISON pages from general FAULT pages, while other
callers will still get -EFAULT for all these pages, so the user space
interface need not to be changed.
This feature is needed by KVM, where UCR MCE should be relayed to
guest for HWPOISON page, while instruction emulation and MMIO will be
tried for general FAULT page.
The idea comes from Andrew Morton.
Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/asm-generic/errno.h | 2 ++
include/linux/mm.h | 1 +
mm/memory.c | 13 ++++++++++---
3 files changed, 13 insertions(+), 3 deletions(-)
--- a/include/asm-generic/errno.h
+++ b/include/asm-generic/errno.h
@@ -108,4 +108,6 @@
#define ERFKILL 132 /* Operation not possible due to RF-kill */
+#define EHWPOISON 133 /* Memory page has hardware error */
+
#endif
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1534,6 +1534,7 @@ struct page *follow_page(struct vm_area_
#define FOLL_FORCE 0x10 /* get_user_pages read/write w/o permission */
#define FOLL_MLOCK 0x40 /* mark page as mlocked */
#define FOLL_SPLIT 0x80 /* don't return transhuge pages, split them */
+#define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */
typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
void *data);
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1576,9 +1576,16 @@ int __get_user_pages(struct task_struct
if (ret & VM_FAULT_ERROR) {
if (ret & VM_FAULT_OOM)
return i ? i : -ENOMEM;
- if (ret &
- (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE|
- VM_FAULT_SIGBUS))
+ if (ret & (VM_FAULT_HWPOISON |
+ VM_FAULT_HWPOISON_LARGE)) {
+ if (i)
+ return i;
+ else if (gup_flags & FOLL_HWPOISON)
+ return -EHWPOISON;
+ else
+ return -EFAULT;
+ }
+ if (ret & VM_FAULT_SIGBUS)
return i ? i : -EFAULT;
BUG();
}
--
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