From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 6B9F16B0007 for ; Wed, 20 Jun 2018 06:57:53 -0400 (EDT) Received: by mail-wr0-f200.google.com with SMTP id z69-v6so2239692wrb.20 for ; Wed, 20 Jun 2018 03:57:53 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 20-v6si1070399edt.303.2018.06.20.03.57.51 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 20 Jun 2018 03:57:51 -0700 (PDT) Subject: Re: [PATCH] thp: use mm_file_counter to determine update which rss counter References: <1529442518-17398-1-git-send-email-yang.shi@linux.alibaba.com> From: Vlastimil Babka Message-ID: <000df63e-2f67-a1a3-42e6-c45d93d960cd@suse.cz> Date: Wed, 20 Jun 2018 12:57:48 +0200 MIME-Version: 1.0 In-Reply-To: <1529442518-17398-1-git-send-email-yang.shi@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Yang Shi , hughd@google.com, kirill.shutemov@linux.intel.com, akpm@linux-foundation.orgAndrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Jerome Marchand On 06/19/2018 11:08 PM, Yang Shi wrote: > Since commit eca56ff906bdd0239485e8b47154a6e73dd9a2f3 ("mm, shmem: add > internal shmem resident memory accounting"), MM_SHMEMPAGES is added to > separate the shmem accounting from regular files. So, all shmem pages > should be accounted to MM_SHMEMPAGES instead of MM_FILEPAGES. > > And, normal 4K shmem pages have been accounted to MM_SHMEMPAGES, so > shmem thp pages should be not treated differently. Accouting them to > MM_SHMEMPAGES via mm_counter_file() since shmem pages are swap backed > to keep consistent with normal 4K shmem pages. > > This will not change the rss counter of processes since shmem pages are > still a part of it. So what are the user-visible effects of the patch then? Let's add this?: The /proc/pid/status and /proc/pid/statm counters will however be more accurate wrt shmem usage, as originally intended. > Signed-off-by: Yang Shi > Cc: Hugh Dickins > Cc: Kirill A. Shutemov Good catch, thanks. I guess the discrepancy happened due to the thp-tmpfs patchset existing externally for a long time and number of iterations, while commit eca56ff906bdd was merged, and nobody noticed that the thp case added more MM_FILEPAGES users. Acked-by: Vlastimil Babka > --- > mm/huge_memory.c | 4 ++-- > mm/memory.c | 2 +- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 1cd7c1a..2687f7c 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1740,7 +1740,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, > } else { > if (arch_needs_pgtable_deposit()) > zap_deposited_table(tlb->mm, pmd); > - add_mm_counter(tlb->mm, MM_FILEPAGES, -HPAGE_PMD_NR); > + add_mm_counter(tlb->mm, mm_counter_file(page), -HPAGE_PMD_NR); > } > > spin_unlock(ptl); > @@ -2088,7 +2088,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, > SetPageReferenced(page); > page_remove_rmap(page, true); > put_page(page); > - add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR); > + add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); > return; > } else if (is_huge_zero_pmd(*pmd)) { > /* > diff --git a/mm/memory.c b/mm/memory.c > index 7206a63..4a2f2a8 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3372,7 +3372,7 @@ static int do_set_pmd(struct vm_fault *vmf, struct page *page) > if (write) > entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); > > - add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR); > + add_mm_counter(vma->vm_mm, mm_counter_file(page), HPAGE_PMD_NR); > page_add_file_rmap(page, true); > /* > * deposit and withdraw with pmd lock held >