mm/huge_memory: access vm_page_prot with READ_ONCE in remove_migratio…

…n_pmd vma->vm_page_prot is read lockless from the rmap_walk, it may be updated concurrently. Using READ_ONCE to prevent the risk of reading intermediate values. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Miaohe Lin <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Muchun Song <[email protected]> Cc: Yang Shi <[email protected]> Cc: Zach O'Keefe <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
apopple-nvidia · Jul 18, 2022 · 4286f14 · 4286f14
1 parent 7c38f18
commit 4286f14
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
@@ -3205,7 +3205,7 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
 
 	entry = pmd_to_swp_entry(*pvmw->pmd);
 	get_page(new);
-	pmde = pmd_mkold(mk_huge_pmd(new, vma->vm_page_prot));
+	pmde = pmd_mkold(mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot)));
 	if (pmd_swp_soft_dirty(*pvmw->pmd))
 		pmde = pmd_mksoft_dirty(pmde);
 	if (is_writable_migration_entry(entry))