[067/118] mm/migrate: add stable check in migrate_vma_insert_page()

Commit Message

Andrew Morton Jan. 31, 2020, 6:14 a.m. UTC

From: Ralph Campbell <[e-mail]>
Subject: mm/migrate: add stable check in migrate_vma_insert_page()

migrate_vma_insert_page() closely follows the code in:
  __handle_mm_fault()
    handle_pte_fault()
      do_anonymous_page()

Add a call to check_stable_address_space() after locking the page table
entry before inserting a ZONE_DEVICE private zero page mapping similar to
page faulting a new anonymous page.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ralph Campbell <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Cc: Jerome Glisse <[e-mail]>
Cc: John Hubbard <[e-mail]>
Cc: Jason Gunthorpe <[e-mail]>
Cc: Bharata B Rao <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Chris Down <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/migrate.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Patch

--- a/mm/migrate.c~mm-migrate-add-stable-check-in-migrate_vma_insert_page
+++ a/mm/migrate.c
@@ -48,6 +48,7 @@ 
 #include <linux/page_owner.h>
 #include <linux/sched/mm.h>
 #include <linux/ptrace.h>
+#include <linux/oom.h>
 
 #include <asm/tlbflush.h>
 
@@ -2695,6 +2696,14 @@  int migrate_vma_setup(struct migrate_vma
 }
 EXPORT_SYMBOL(migrate_vma_setup);
 
+/*
+ * This code closely matches the code in:
+ *   __handle_mm_fault()
+ *     handle_pte_fault()
+ *       do_anonymous_page()
+ * to map in an anonymous zero page but the struct page will be a ZONE_DEVICE
+ * private page.
+ */
 static void migrate_vma_insert_page(struct migrate_vma *migrate,
 				    unsigned long addr,
 				    struct page *page,
@@ -2775,6 +2784,9 @@  static void migrate_vma_insert_page(stru
 
 	ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl);
 
+	if (check_stable_address_space(mm))
+		goto unlock_abort;
+
 	if (pte_present(*ptep)) {
 		unsigned long pfn = pte_pfn(*ptep);