Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1434717AbdDZDJr convert rfc822-to-8bit (ORCPT ); Tue, 25 Apr 2017 23:09:47 -0400 Received: from tyo162.gate.nec.co.jp ([114.179.232.162]:60548 "EHLO tyo162.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1430452AbdDZDJk (ORCPT ); Tue, 25 Apr 2017 23:09:40 -0400 From: Naoya Horiguchi To: Balbir Singh CC: Laurent Dufour , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "akpm@linux-foundation.org" Subject: Re: [PATCH v2 1/2] mm: Uncharge poisoned pages Thread-Topic: [PATCH v2 1/2] mm: Uncharge poisoned pages Thread-Index: AQHSvdAlGOZ3BQwtDkae9J7zLQT7cKHWTbcAgAAK9AA= Date: Wed, 26 Apr 2017 02:34:11 +0000 Message-ID: <20170426023410.GA11619@hori1.linux.bs1.fc.nec.co.jp> References: <1493130472-22843-1-git-send-email-ldufour@linux.vnet.ibm.com> <1493130472-22843-2-git-send-email-ldufour@linux.vnet.ibm.com> <1493171698.4828.1.camel@gmail.com> In-Reply-To: <1493171698.4828.1.camel@gmail.com> Accept-Language: en-US, ja-JP Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.128.101.32] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-TM-AS-MML: disable Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3211 Lines: 69 On Wed, Apr 26, 2017 at 11:54:58AM +1000, Balbir Singh wrote: > On Tue, 2017-04-25 at 16:27 +0200, Laurent Dufour wrote: > > When page are poisoned, they should be uncharged from the root memory > > cgroup. > > > > This is required to avoid a BUG raised when the page is onlined back: > > BUG: Bad page state in process mem-on-off-test pfn:7ae3b > > page:f000000001eb8ec0 count:0 mapcount:0 mapping: (null) > > index:0x1 > > flags: 0x3ffff800200000(hwpoison) > > raw: 003ffff800200000 0000000000000000 0000000000000001 > > 00000000ffffffff > > raw: 5deadbeef0000100 5deadbeef0000200 0000000000000000 > > c0000007fe055800 > > page dumped because: page still charged to cgroup > > page->mem_cgroup:c0000007fe055800 > > Modules linked in: pseries_rng rng_core vmx_crypto virtio_balloon > > ip_tables x_tables autofs4 virtio_blk virtio_net virtio_pci > > virtio_ring virtio > > CPU: 34 PID: 5946 Comm: mem-on-off-test Tainted: G B 4.11.0-rc7-hwp > > Call Trace: > > [c0000007e4a737f0] [c000000000958e8c] dump_stack+0xb0/0xf0 > > (unreliable) > > [c0000007e4a73830] [c00000000021588c] bad_page+0x11c/0x190 > > [c0000007e4a738c0] [c00000000021757c] free_pcppages_bulk+0x46c/0x600 > > [c0000007e4a73990] [c00000000021924c] free_hot_cold_page+0x2ec/0x320 > > [c0000007e4a739e0] [c0000000002a6440] generic_online_page+0x50/0x70 > > [c0000007e4a73a10] [c0000000002a6184] online_pages_range+0x94/0xe0 > > [c0000007e4a73a70] [c00000000005a2b0] walk_system_ram_range+0xe0/0x120 > > [c0000007e4a73ac0] [c0000000002cce44] online_pages+0x2b4/0x6b0 > > [c0000007e4a73b60] [c000000000600558] memory_subsys_online+0x218/0x270 > > [c0000007e4a73bf0] [c0000000005dec84] device_online+0xb4/0x110 > > [c0000007e4a73c30] [c000000000600f00] store_mem_state+0xc0/0x190 > > [c0000007e4a73c70] [c0000000005da1d4] dev_attr_store+0x34/0x60 > > [c0000007e4a73c90] [c000000000377c70] sysfs_kf_write+0x60/0xa0 > > [c0000007e4a73cb0] [c0000000003769fc] kernfs_fop_write+0x16c/0x240 > > [c0000007e4a73d00] [c0000000002d1b0c] __vfs_write+0x3c/0x1b0 > > [c0000007e4a73d90] [c0000000002d34dc] vfs_write+0xcc/0x230 > > [c0000007e4a73de0] [c0000000002d50e0] SyS_write+0x60/0x110 > > [c0000007e4a73e30] [c00000000000b760] system_call+0x38/0xfc > > > > Signed-off-by: Laurent Dufour > > --- > > mm/memory-failure.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > > index 27f7210e7fab..22bd22eb25cb 100644 > > --- a/mm/memory-failure.c > > +++ b/mm/memory-failure.c > > @@ -529,6 +529,9 @@ static const char * const action_page_types[] = { > > */ > > static int delete_from_lru_cache(struct page *p) > > { > > + if (memcg_kmem_enabled()) > > + memcg_kmem_uncharge(p, 0); > > + > > The changelog is not quite clear, so we are uncharging a page using > memcg_kmem_uncharge for a page in swap cache/page cache? Hi Balbir, Yes, in the normal page lifecycle, uncharge is done in page free time. But in memory error handling case, in-use pages (i.e. swap cache and page cache) are removed from normal path and they don't pass page freeing code. So I think that this change is to keep the consistent charging for such a case. - Naoya Horiguchi