From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id B46486B01EF for ; Wed, 21 Apr 2010 06:29:07 -0400 (EDT) Received: by wwc33 with SMTP id 33so3691652wwc.14 for ; Wed, 21 Apr 2010 03:29:05 -0700 (PDT) Date: Wed, 21 Apr 2010 12:27:59 +0200 From: Dan Carpenter Subject: [patch] ksm: check for ERR_PTR from follow_page() Message-ID: <20100421102759.GA29647@bicker> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org To: Izik Eidus Cc: Hugh Dickins , Andrea Arcangeli , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-janitors@vger.kernel.org, Andrew Morton List-ID: The follow_page() function can potentially return -EFAULT so I added checks for this. Also I silenced an uninitialized variable warning on my version of gcc (version 4.3.2). Signed-off-by: Dan Carpenter --- I'm not very familiar with this code, so handle with care. diff --git a/mm/ksm.c b/mm/ksm.c index 8cdfc2a..956880f 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -365,7 +365,7 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr) do { cond_resched(); page = follow_page(vma, addr, FOLL_GET); - if (!page) + if (IS_ERR_OR_NULL(page)) break; if (PageKsm(page)) ret = handle_mm_fault(vma->vm_mm, vma, addr, @@ -447,7 +447,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item) goto out; page = follow_page(vma, addr, FOLL_GET); - if (!page) + if (IS_ERR_OR_NULL(page)) goto out; if (PageAnon(page)) { flush_anon_page(vma, page, addr); @@ -1086,7 +1086,7 @@ struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item, cond_resched(); tree_rmap_item = rb_entry(*new, struct rmap_item, node); tree_page = get_mergeable_page(tree_rmap_item); - if (!tree_page) + if (IS_ERR_OR_NULL(tree_page)) return NULL; /* @@ -1294,7 +1294,7 @@ next_mm: if (ksm_test_exit(mm)) break; *page = follow_page(vma, ksm_scan.address, FOLL_GET); - if (*page && PageAnon(*page)) { + if (!IS_ERR_OR_NULL(*page) && PageAnon(*page)) { flush_anon_page(vma, *page, ksm_scan.address); flush_dcache_page(*page); rmap_item = get_next_rmap_item(slot, @@ -1308,7 +1308,7 @@ next_mm: up_read(&mm->mmap_sem); return rmap_item; } - if (*page) + if (!IS_ERR_OR_NULL(*page)) put_page(*page); ksm_scan.address += PAGE_SIZE; cond_resched(); @@ -1367,7 +1367,7 @@ next_mm: static void ksm_do_scan(unsigned int scan_npages) { struct rmap_item *rmap_item; - struct page *page; + struct page *uninitialized_var(page); while (scan_npages--) { cond_resched(); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org