From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id 8DDC828027E for ; Wed, 15 Jul 2015 02:34:20 -0400 (EDT) Received: by padck2 with SMTP id ck2so18549942pad.0 for ; Tue, 14 Jul 2015 23:34:20 -0700 (PDT) Received: from mail-pd0-x230.google.com (mail-pd0-x230.google.com. [2607:f8b0:400e:c02::230]) by mx.google.com with ESMTPS id es7si5786422pbd.123.2015.07.14.23.34.19 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 Jul 2015 23:34:19 -0700 (PDT) Received: by pdbqm3 with SMTP id qm3so19360429pdb.0 for ; Tue, 14 Jul 2015 23:34:19 -0700 (PDT) From: 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> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Mel Gorman , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim 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, 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