From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753391AbcDVHln (ORCPT ); Fri, 22 Apr 2016 03:41:43 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:48644 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751465AbcDVHlk (ORCPT ); Fri, 22 Apr 2016 03:41:40 -0400 From: Chen Feng Subject: Is the page always in swapcache? To: , , , , , , , , , CC: Zhuangluan Su , Dan Zhao , l00215322 , Yiping Xu , , , "yudongbin@hisilicon.com" , Message-ID: <5719D549.6020400@hisilicon.com> Date: Fri, 22 Apr 2016 15:39:53 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.142.193.64] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020206.5719D55C.0100,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 745597d605cec22807fe92af9be4e1f1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Matainers, In the file mm/migrate.c 316 int migrate_page_move_mapping(struct address_space *mapping, 317 struct page *newpage, struct page *page, 318 struct buffer_head *head, enum migrate_mode mode, 319 int extra_count) 320 { 321 struct zone *oldzone, *newzone; 322 int dirty; 323 int expected_count = 1 + extra_count; 324 void **pslot; .... 344 345 pslot = radix_tree_lookup_slot(&mapping->page_tree, 346 page_index(page)); 347 348 expected_count += 1 + page_has_private(page); 349 if (page_count(page) != expected_count || 350 radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) { ... 353 } In the line 345, Is the page is always in the swap-cache? I got the follow crash issue with compaction. [ 4433.467956s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 4433.467987s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]pgd = ffffffc0b46f9000 [ 4433.467987s][00000000] *pgd=0000000000000000 [ 4433.468017s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 4433.468048s]Modules linked in: [ 4433.468078s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]CPU: 2 PID: 324 Comm: lmkd Tainted: G W 3.10.94-g0daa20e #1 [ 4433.468109s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]task: ffffffc0b7783980 ti: ffffffc0b46c8000 task.ti: ffffffc0b46c8000 [ 4433.468139s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]PC is at migrate_page_move_mapping.part.28+0x7c/0x21c [ 4433.468170s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]LR is at migrate_page_move_mapping.part.28+0x50/0x21c [ 4433.468170s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]pc : [] lr : [] pstate: 60000185 [ 4433.468200s][2016:04:13 11:06:41][pid:324,cpu2,lmkd]sp : ffffffc0b46cbb20 [ 4433.468200s]x29: ffffffc0b46cbb20 x28: 00000000fffffff5 [ 4433.468231s]x27: ffffffc0bb20b000 x26: 0000000000000000 [ 4433.468261s]x25: 0000000000000000 x24: 0000000000000001 [ 4433.468292s]x23: ffffffc0013be1a8 x22: 0000000000000000 [ 4433.468322s]x21: 0000000000000002 x20: ffffffc0bdbfc900 [ 4433.468353s]x19: ffffffc0bb20b000 x18: 0000000000000000 [ 4433.468353s]x17: 0000000000000000 x16: 0000000000000000 [ 4433.468383s]x15: 0000000000000000 x14: fffffff8fffffff8 [ 4433.468414s]x13: fffffff8fffffff8 x12: fffffff8fffffff8 [ 4433.468444s]x11: fffffff8fffffff8 x10: 00000000ffffffff [ 4433.468475s]x9 : d61f0220913be210 x8 : ffffffc0ba60ee80 [ 4433.468475s]x7 : 0000000000000006 x6 : 0000000000000001 [ 4433.468505s]x5 : 000001440006010b x4 : 0000000000000001 [ 4433.468536s]x3 : 0000000000000000 x2 : 000001440006010b [ 4433.468566s]x1 : 000001440006010b x0 : 0000000000000002 [ 4433.468597s][2016:04:13 11:06:41][pid:324,cpu2,lmkd] [ 4433.468597s]PC: 0xffffffc000192838: [ 4433.468597s]2838 d65f03c0 a9bb7bfd 910003fd a90363f7 91006017 2a0403f8 a90153f3 a9025bf5 [ 4433.468658s]2858 aa0203f3 aa0003f5 aa1703e0 aa0103f4 a9046bf9 aa0303f9 942c336b f9400260 [ 4433.468719s]2878 910022b5 37880ba0 f9400a61 aa1503e0 9407a477 aa0003fa f9400262 aa1303e0 [ 4433.468780s]2898 f9400261 f274045f 1a9f07f6 11000ad5 37800a81 b9401c00 6b0002bf 540008a1 [ 4433.468811s]28b8 f9400340 eb00027f 54000841 d5033bbf 52800001 91007263 885f7c60 6b15001f [ 4433.468872s]28d8 54000061 88027c61 35ffff82 d5033bbf 6b0002bf 540006e1 350000d8 b40000b9 [ 4433.468933s]28f8 aa1903e0 97ffff8f 53001c00 34000600 f9400280 378009c0 91007282 885f7c40 [ 4433.468994s]2918 11000400 88017c40 35ffffa1 f9400260 37880420 12000295 37000734 d5033abf