HWPOISON: Add basic support for poisoned pages in fault handler v3

- Add a new VM_FAULT_HWPOISON error code to handle_mm_fault. Right now
architectures have to explicitely enable poison page support, so
this is forward compatible to all architectures. They only need
to add it when they enable poison page support.
- Add poison page handling in swap in fault code

v2: Add missing delayacct_clear_flag (Hidehiro Kawai)
v3: Really use delayacct_clear_flag (Hidehiro Kawai)

Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/mm/memory.c b/mm/memory.c
index aede2ce3aba4..02bae2d540d4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1319,7 +1319,8 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                                 if (ret & VM_FAULT_ERROR) {
                                         if (ret & VM_FAULT_OOM)
                                                 return i ? i : -ENOMEM;
-                                        else if (ret & VM_FAULT_SIGBUS)
+                                        if (ret &
+                                            (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
                                                 return i ? i : -EFAULT;
                                         BUG();
                                 }
@@ -2511,8 +2512,15 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 goto out;
 
         entry = pte_to_swp_entry(orig_pte);
-        if (is_migration_entry(entry)) {
-                migration_entry_wait(mm, pmd, address);
+        if (unlikely(non_swap_entry(entry))) {
+                if (is_migration_entry(entry)) {
+                        migration_entry_wait(mm, pmd, address);
+                } else if (is_hwpoison_entry(entry)) {
+                        ret = VM_FAULT_HWPOISON;
+                } else {
+                        print_bad_pte(vma, address, orig_pte, NULL);
+                        ret = VM_FAULT_OOM;
+                }
                 goto out;
         }
         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
@@ -2536,6 +2544,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                 /* Had to read the page from swap area: Major fault */
                 ret = VM_FAULT_MAJOR;
                 count_vm_event(PGMAJFAULT);
+        } else if (PageHWPoison(page)) {
+                ret = VM_FAULT_HWPOISON;
+                delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+                goto out;
         }
 
         lock_page(page);