Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932232AbcLLF7N (ORCPT ); Mon, 12 Dec 2016 00:59:13 -0500 Received: from mail-qt0-f195.google.com ([209.85.216.195]:32870 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750830AbcLLF7M (ORCPT ); Mon, 12 Dec 2016 00:59:12 -0500 From: Jia He To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , Vlastimil Babka , Mel Gorman , Michal Hocko , Johannes Weiner , Joonsoo Kim , Taku Izumi , Jia He Subject: [PATCH RFC 0/1] mm, page_alloc: fix incorrect zone_statistics data Date: Mon, 12 Dec 2016 13:59:06 +0800 Message-Id: <1481522347-20393-1-git-send-email-hejianet@gmail.com> X-Mailer: git-send-email 2.5.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3490 Lines: 54 In commit b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics"), it reconstructed the code to reduce the branch miss rate. Compared with the original logic, it assumed if !(flag & __GFP_OTHER_NODE) z->node would not be equal to preferred_zone->node. That seems to be incorrect. Here is what I catch, dumpstack() is triggered when z->node == preferred_zone->node and z->node != numa_node_id() z=5,prefer=5,local=4, flag&OTHER_NODE=0 [c000000cdcaef440] [c0000000002e88cc] cache_grow_begin+0xcc/0x500 [c000000cdcaef6f0] [c0000000002ecb44] do_tune_cpucache+0x64/0x100 [c000000cdcaef750] [c0000000002ecc7c] enable_cpucache+0x9c/0x180 [c000000cdcaef7d0] [c0000000002ed01c] __kmem_cache_create+0x1ec/00x2c0 [c000000cdcaef820] [c000000000291c98] create_cache+0xb8/0x240 [c000000cdcaef890] [c000000000291fa8] kmem_cache_create+0x188/0x2290 [c000000cdcaef950] [d000000011dc5c70] ext4_mb_init+0x3c0/0x5e0 [eext4] [c000000cdcaef9f0] [d000000011daaedc] ext4_fill_super+0x266c/0x33390 [ext4] [c000000cdcaefb30] [c000000000328b8c] mount_bdev+0x22c/0x260 [c000000cdcaefbd0] [d000000011da1fa8] ext4_mount+0x48/0x60 [ext4] [c000000cdcaefc10] [c00000000032a11c] mount_fs+0x8c/0x230 [c000000cdcaefcb0] [c000000000351f98] vfs_kern_mount+0x78/0x180 [c000000cdcaefd00] [c000000000356d68] do_mount+0x258/0xea0 [c000000cdcaefde0] [c000000000357da0] SyS_mount+0xa0/0x110 [c000000cdcaefe30] [c00000000000bd84] system_call+0x38/0xe0 Before this patch, the numa_miss and numa_foreign looked very odd: linux:~ # numastat node0 node1 node2 node3 node4 node5 node6 numa_hit 42216 0 0 0 96755 0 0 numa_miss 1 718 711 726 860 712 719 numa_foreign 1 718 711 726 860 712 719 interleave_hit 631 638 632 641 621 633 636 local_node 42216 0 0 0 96755 0 0 other_node 0 0 0 0 0 0 0 After this patch linux:~ # numastat node0 node1 node2 node3 node4 node5 node6 numa_hit 177891 718 711 726 60302 712 719 numa_miss 0 196944 237222 253424 0 36265 0 numa_foreign 723855 0 0 0 0 0 0 interleave_hit 631 638 632 641 621 633 636 local_node 177891 0 0 0 59444 0 0 other_node 0 718 711 726 858 712 719 Jia He (1): mm, page_alloc: fix incorrect zone_statistics data mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.5.5