1 files changed, 7 insertions, 27 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index 051cc1555d36..e84eeb4e4356 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -41,6 +41,7 @@
 #include <linux/page_idle.h>
 #include <linux/page_owner.h>
 #include <linux/sched/mm.h>
+#include <linux/ptrace.h>
 
 #include <asm/tlbflush.h>
 
@@ -1252,6 +1253,8 @@ put_anon:
 out:
 	if (rc != -EAGAIN)
 		putback_active_hugepage(hpage);
+	if (reason == MR_MEMORY_FAILURE && !test_set_page_hwpoison(hpage))
+		num_poisoned_pages_inc();
 
 	/*
 	 * If migration was not successful and there's a freeing callback, use
@@ -1650,7 +1653,6 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
 		const int __user *, nodes,
 		int __user *, status, int, flags)
 {
-	const struct cred *cred = current_cred(), *tcred;
 	struct task_struct *task;
 	struct mm_struct *mm;
 	int err;
@@ -1674,14 +1676,9 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,
 
 	/*
 	 * Check if this process has the right to modify the specified
-	 * process. The right exists if the process has administrative
-	 * capabilities, superuser privileges or the same
-	 * userid as the target process.
+	 * process. Use the regular "ptrace_may_access()" checks.
 	 */
-	tcred = __task_cred(task);
-	if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
-	    !uid_eq(cred->uid,  tcred->suid) && !uid_eq(cred->uid,  tcred->uid) &&
-	    !capable(CAP_SYS_NICE)) {
+	if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
 		rcu_read_unlock();
 		err = -EPERM;
 		goto out;
@@ -1914,7 +1911,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 	int page_lru = page_is_file_cache(page);
 	unsigned long mmun_start = address & HPAGE_PMD_MASK;
 	unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE;
-	pmd_t orig_entry;
 
 	/*
 	 * Rate-limit the amount of data that is being migrated to a node.
@@ -1936,12 +1932,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 		put_page(new_page);
 		goto out_fail;
 	}
-	/*
-	 * We are not sure a pending tlb flush here is for a huge page
-	 * mapping or not. Hence use the tlb range variant
-	 */
-	if (mm_tlb_flush_pending(mm))
-		flush_tlb_range(vma, mmun_start, mmun_end);
 
 	/* Prepare a page as a migration target */
 	__SetPageLocked(new_page);
@@ -1957,8 +1947,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 	/* Recheck the target PMD */
 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 	ptl = pmd_lock(mm, pmd);
-	if (unlikely(!pmd_same(*pmd, entry) || page_count(page) != 2)) {
-fail_putback:
+	if (unlikely(!pmd_same(*pmd, entry) || !page_ref_freeze(page, 2))) {
 		spin_unlock(ptl);
 		mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
 
@@ -1980,7 +1969,6 @@ fail_putback:
 		goto out_unlock;
 	}
 
-	orig_entry = *pmd;
 	entry = mk_huge_pmd(new_page, vma->vm_page_prot);
 	entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 
@@ -1997,15 +1985,7 @@ fail_putback:
 	set_pmd_at(mm, mmun_start, pmd, entry);
 	update_mmu_cache_pmd(vma, address, &entry);
 
-	if (page_count(page) != 2) {
-		set_pmd_at(mm, mmun_start, pmd, orig_entry);
-		flush_pmd_tlb_range(vma, mmun_start, mmun_end);
-		mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
-		update_mmu_cache_pmd(vma, address, &entry);
-		page_remove_rmap(new_page, true);
-		goto fail_putback;
-	}
-
+	page_ref_unfreeze(page, 2);
 	mlock_migrate_page(new_page, page);
 	page_remove_rmap(page, true);
 	set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED);