From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id 120C96B0038 for ; Wed, 2 Dec 2015 21:09:53 -0500 (EST) Received: by pacdm15 with SMTP id dm15so56950607pac.3 for ; Wed, 02 Dec 2015 18:09:52 -0800 (PST) Received: from lgeamrelo13.lge.com (LGEAMRELO13.lge.com. [156.147.23.53]) by mx.google.com with ESMTPS id f2si8498344pfj.59.2015.12.02.18.09.51 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 02 Dec 2015 18:09:52 -0800 (PST) Date: Thu, 3 Dec 2015 11:10:06 +0900 From: Minchan Kim Subject: Re: memcg uncharge page counter mismatch Message-ID: <20151203021006.GA31041@bbox> References: <20151201133455.GB27574@bbox> <20151202101643.GC25284@dhcp22.suse.cz> <20151203013404.GA30779@bbox> MIME-Version: 1.0 In-Reply-To: <20151203013404.GA30779@bbox> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , "Kirill A. Shutemov" , Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Dec 03, 2015 at 10:34:04AM +0900, Minchan Kim wrote: > On Wed, Dec 02, 2015 at 11:16:43AM +0100, Michal Hocko wrote: > > On Tue 01-12-15 22:34:55, Minchan Kim wrote: > > > With new test on mmotm-2015-11-25-17-08, I saw below WARNING message > > > several times. I couldn't see it with reverting new THP refcount > > > redesign. > > > > Just a wild guess. What prevents migration/compaction from calling > > split_huge_page on thp zero page? There is VM_BUG_ON but it is not clear > > I guess migration should work with LRU pages now but zero page couldn't > stay there. > > > whether you run with CONFIG_DEBUG_VM enabled. > > I enabled VM_DEBUG_VM. > > > > > Also, how big is the underflow? > > diff --git a/mm/page_counter.c b/mm/page_counter.c > index 7c6a63d..adc27c3 100644 > --- a/mm/page_counter.c > +++ b/mm/page_counter.c > @@ -23,6 +23,8 @@ void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages) > > new = atomic_long_sub_return(nr_pages, &counter->count); > /* More uncharges than charges? */ > + if (new < 0) > + printk("nr_pages %lu new %ld\n", nr_pages, new); > WARN_ON_ONCE(new < 0); > } > > nr_pages 512 new -31 > ------------[ cut here ]------------ > WARNING: CPU: 3 PID: 1145 at mm/page_counter.c:28 page_counter_cancel+0x44/0x50() > Modules linked in: > CPU: 3 PID: 1145 Comm: madvise_test Not tainted 4.4.0-rc2-mm1-kirill+ #17 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > ffffffff81782f09 ffff8800598c3b90 ffffffff8126f476 0000000000000000 > ffff8800598c3bc8 ffffffff8103e476 ffff88007f14f8b0 0000000000000200 > 0000000000000000 0000000000000200 ffff88007f14f800 ffff8800598c3bd8 > Call Trace: > [] dump_stack+0x44/0x5e > [] warn_slowpath_common+0x86/0xc0 > [] warn_slowpath_null+0x1a/0x20 > [] page_counter_cancel+0x44/0x50 > [] page_counter_uncharge+0x22/0x30 > [] uncharge_batch+0x47/0x140 > [] uncharge_list+0x123/0x190 > [] mem_cgroup_uncharge+0x29/0x30 > [] __page_cache_release+0x15e/0x200 > [] __put_compound_page+0x1e/0x50 > [] release_pages+0xd0/0x370 > [] free_pages_and_swap_cache+0x9d/0x120 > [] tlb_flush_mmu_free+0x36/0x60 > [] tlb_finish_mmu+0x1c/0x50 > [] exit_mmap+0xec/0x140 > [] mmput+0x56/0xe0 > [] do_exit+0x1fd/0xaa0 > [] do_group_exit+0x3f/0xb0 > [] SyS_exit_group+0x14/0x20 > [] entry_SYSCALL_64_fastpath+0x12/0x6a > ---[ end trace 872ed93351e964c0 ]--- > nr_pages 293 new -324 > nr_pages 16 new -340 > nr_pages 342 new -91 > nr_pages 246 new -337 > nr_pages 15 new -352 > nr_pages 15 new -367 My guess is that it's related to new feature of Kirill's THP 'PageDoubleMap' so a THP page could be mapped a pte but !pmd_trans_huge(*pmd) so memcg precharge in move_charge should handle it? -- 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