From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f198.google.com (mail-qt0-f198.google.com [209.85.216.198]) by kanga.kvack.org (Postfix) with ESMTP id 1010C6B0038 for ; Mon, 12 Dec 2016 00:59:12 -0500 (EST) Received: by mail-qt0-f198.google.com with SMTP id 41so61023841qtn.7 for ; Sun, 11 Dec 2016 21:59:12 -0800 (PST) Received: from mail-qt0-x241.google.com (mail-qt0-x241.google.com. [2607:f8b0:400d:c0d::241]) by mx.google.com with ESMTPS id k6si25634161qkf.38.2016.12.11.21.59.11 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 11 Dec 2016 21:59:11 -0800 (PST) Received: by mail-qt0-x241.google.com with SMTP id n34so8610297qtb.3 for ; Sun, 11 Dec 2016 21:59:11 -0800 (PST) From: 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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 -- 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