Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752815AbbGOGeX (ORCPT ); Wed, 15 Jul 2015 02:34:23 -0400 Received: from mail-pd0-f173.google.com ([209.85.192.173]:33903 "EHLO mail-pd0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751565AbbGOGeU (ORCPT ); Wed, 15 Jul 2015 02:34:20 -0400 From: Joonsoo Kim X-Google-Original-From: Joonsoo Kim To: Andrew Morton Cc: Mel Gorman , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim Subject: [PATCH 1/2] mm/page_owner: fix possible access violation Date: Wed, 15 Jul 2015 15:33:58 +0900 Message-Id: <1436942039-16897-1-git-send-email-iamjoonsoo.kim@lge.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3859 Lines: 82 When I tested my new patches, I found that page pointer which is used for setting page_owner information is changed. This is because page pointer is used to set new migratetype in loop. After this work, page pointer could be out of bound. If this wrong pointer is used for page_owner, access violation happens. Below is error message that I got. [ 6175.025217] BUG: unable to handle kernel paging request at 0000000000b00018 [ 6175.026400] IP: [] save_stack_address+0x30/0x40 [ 6175.027341] PGD 1af2d067 PUD 166e0067 PMD 0 [ 6175.028129] Oops: 0002 [#1] SMP snip... [ 6175.055349] Call Trace: [ 6175.055780] [] print_context_stack+0xcf/0x100 [ 6175.056794] [] ? __module_text_address+0x12/0x70 [ 6175.057848] [] dump_trace+0x15f/0x320 [ 6175.058751] [] ? do_flush_tlb_all+0x50/0x50 [ 6175.059732] [] ? smp_call_function_single+0xb9/0x120 [ 6175.060856] [] save_stack_trace+0x2f/0x50 [ 6175.061812] [] __set_page_owner+0x46/0x70 [ 6175.062774] [] __isolate_free_page+0x1f7/0x210 [ 6175.063804] [] split_free_page+0x21/0xb0 [ 6175.064757] [] isolate_freepages_block+0x1e2/0x410 [ 6175.065855] [] compaction_alloc+0x22d/0x2d0 [ 6175.066850] [] migrate_pages+0x289/0x8b0 [ 6175.067798] [] ? isolate_migratepages_block+0x28a/0x6e0 [ 6175.068960] [] ? kmalloc_slab+0xa0/0xa0 [ 6175.069892] [] ? ftrace_raw_event_mm_compaction_deplete_template+0xc0/0xc0 [ 6175.071327] [] compact_zone+0x409/0x880 [ 6175.072261] [] compact_zone_order+0x6d/0x90 [ 6175.073250] [] try_to_compact_pages+0x110/0x210 [ 6175.074297] [] __alloc_pages_direct_compact+0x3d/0xe6 [ 6175.075427] [] __alloc_pages_nodemask+0x6cd/0x9a0 [ 6175.076517] [] alloc_pages_current+0x91/0x100 [ 6175.077545] [] runtest_store+0x296/0xa50 [ 6175.078497] [] ? simple_strtoull+0x2c/0x50 [ 6175.079465] [] simple_attr_write+0xbd/0xe0 [ 6175.080458] [] __vfs_write+0x28/0xf0 [ 6175.081349] [] ? __sb_start_write+0x49/0xf0 [ 6175.082345] [] ? security_file_permission+0x45/0xd0 [ 6175.083453] [] vfs_write+0xa9/0x1b0 [ 6175.084334] [] SyS_write+0x46/0xb0 [ 6175.085196] [] ? context_tracking_user_enter+0x13/0x20 [ 6175.086339] [] ? syscall_trace_leave+0xa5/0x120 [ 6175.087389] [] system_call_fastpath+0x16/0x75 This patch fixes this error by moving up set_page_owner(). Signed-off-by: Joonsoo Kim --- mm/page_alloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index afd5459..70d6a85 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2003,6 +2003,8 @@ int __isolate_free_page(struct page *page, unsigned int order) zone->free_area[order].nr_free--; rmv_page_order(page); + set_page_owner(page, order, 0); + /* Set the pageblock if the isolated page is at least a pageblock */ if (order >= pageblock_order - 1) { struct page *endpage = page + (1 << order) - 1; @@ -2014,7 +2016,7 @@ int __isolate_free_page(struct page *page, unsigned int order) } } - set_page_owner(page, order, 0); + return 1UL << order; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/