If fail to migrate thp(due to unsuccessful isolation), and if the original pmd entry is changed after reaquiring page table lock, it is unsafe to release the page lock as page maybe unstable.
It is fixed by raising extra page count before trying migration. Signed-off-by: Hillf Danton <dhi...@gmail.com> --- --- a/mm/huge_memory.c Fri Nov 23 22:07:38 2012 +++ b/mm/huge_memory.c Fri Nov 23 22:55:32 2012 @@ -1060,11 +1060,13 @@ int do_huge_pmd_numa_page(struct mm_stru } spin_unlock(&mm->page_table_lock); + get_page(page); /* Migrate the THP to the requested node */ migrated = migrate_misplaced_transhuge_page(mm, vma, pmdp, pmd, addr, page, target_nid); if (migrated) { + put_page(page); count_vm_numa_event(NUMA_THP_MIGRATE_SUCCESS); current_nid = target_nid; } else { @@ -1072,8 +1074,10 @@ int do_huge_pmd_numa_page(struct mm_stru spin_lock(&mm->page_table_lock); if (unlikely(!pmd_same(pmd, *pmdp))) { unlock_page(page); + put_page(page); goto out_unlock; } + put_page(page); goto clear_pmdnuma; } -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/