From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6766DC10F03 for ; Wed, 24 Apr 2019 00:22:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EAE79217D9 for ; Wed, 24 Apr 2019 00:22:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EAE79217D9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7F68F6B0005; Tue, 23 Apr 2019 20:22:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7A47C6B0006; Tue, 23 Apr 2019 20:22:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 693756B0007; Tue, 23 Apr 2019 20:22:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 319476B0005 for ; Tue, 23 Apr 2019 20:22:52 -0400 (EDT) Received: by mail-pf1-f200.google.com with SMTP id n63so10692986pfb.14 for ; Tue, 23 Apr 2019 17:22:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:subject:from :to:cc:references:message-id:date:user-agent:mime-version :in-reply-to:content-transfer-encoding:content-language; bh=i7nM6cZXenJhVdsE/ILisLsz7vFb5CPoe27Cs+FCmA4=; b=Cq7IARDzwwUa4Vh26JKs7WAZajGu/PcyQqw6ZW4/EvsVMhAY9GpLEBWRD670HpDjOb iIBvS0CsGau8bznYHs7WxQabGoyZ4F/Pdv532OhI4Zexq80iwmN64yG6yGj0xjGw/u3g bBf+u2cISnY28bZLVGx5aO4w1NaNY0nuvpgkAU8tRZ0OfeNE/TcjYlv+Veb84kBLleC3 RHDMYBU3mjFXJASIFkC5xOTWWfpAATJawQ9rIBBzLan7C55Jxu/289I3PMmyjxKmFaw2 PsSrWgB/+C0vBR/q0hRFB/jUwyVZqzmunbfHjottFaRBNE9CnK2mTMqvPWpXIjlNZTts ycRA== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.57 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com X-Gm-Message-State: APjAAAUbbGNnUvTGsKMGpxzo38ILQKt7b1DgPO5I8YrFdvGJBTiFN4my SvEHu6tqMEqyVARF4rF6oWlviAoIMk3RBNqvhhNs1Q+H7lz55aX2cytPzZHg/ntiYSNCuJMTRmt yjhFx/grvxHWRPgrGHgb6pwZ6Y2koy7k1R0riZtz7AjUwzxZWv2Pu45yU+gjV74naUQ== X-Received: by 2002:a17:902:2927:: with SMTP id g36mr27853930plb.6.1556065371602; Tue, 23 Apr 2019 17:22:51 -0700 (PDT) X-Google-Smtp-Source: APXvYqzdWyC+E5YvAACPCIjLRNJlYMLe50hjo7awhXhC4sB+7aO2cCrmkhqzVzWMuvkRHAHplseq X-Received: by 2002:a17:902:2927:: with SMTP id g36mr27853857plb.6.1556065370579; Tue, 23 Apr 2019 17:22:50 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1556065370; cv=none; d=google.com; s=arc-20160816; b=CdlhYu4X+8PBz0QjMhx/pVsohHb6+qKBljHgQS4N6+VUjEL37Dd+O8nmzuCquzPOlV 5Ies5uKhkeY424WC+A6/EnT1B8ToD8KfsQixJbYvZnIruLiuMtA7T5RwxIZaBO5h9uuh uFhw4IMpVYPmp7Aco1P1mjUdiryXTlfNBU524pLbznqels8MjtF331YiPjwmeOYgveDj 8NYs6DCyiJtkPWR5z7IhDMe4dT4YyaHKDAbcy7ldZWjzOmF24EIU7gPrNfazyLJcpZkk SaOGZwtc3bVKmdfQwwbpZhDzc39OKrqmu9QiP8SHEMk2LakIfpdEZhxGXbXxqLe3pvGc 0bzg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-language:content-transfer-encoding:in-reply-to:mime-version :user-agent:date:message-id:references:cc:to:from:subject; bh=i7nM6cZXenJhVdsE/ILisLsz7vFb5CPoe27Cs+FCmA4=; b=rNdwpRZ9C8qLYJ2LRZMzqt+i/GHX/COBD5MMNLvHsUE9evUdXgi9qNtJB9Ih+8Bv/I jCGDGyvR3nNCZQ4Cm1k0w/7Bt2PY8y6K29D4/clUoCxAwsHE3kGj4eczAwepU7BNuGVh xhtfuryuN6hg4TXEbuHuq/9zEvChIhJZel1luB5pyiPPxh+P+nrty0+Do6lK/UTUSv5b Azjmsb2OQ8msrAKR9QioTWCORpzfo6vb94/qI+vnch3mR9XycOx6j5umJAxOdV3IB4jW I+pFbco1BnnB8lbVnYq/Yg0dDRVvjW2iq+WdvTFejH5YGHM8JKo9sxr/kPI5uvAIxCS/ EuWw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.57 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com. [115.124.30.57]) by mx.google.com with ESMTPS id k70si15969031pgd.75.2019.04.23.17.22.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Apr 2019 17:22:50 -0700 (PDT) Received-SPF: pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.57 as permitted sender) client-ip=115.124.30.57; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yang.shi@linux.alibaba.com designates 115.124.30.57 as permitted sender) smtp.mailfrom=yang.shi@linux.alibaba.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alibaba.com X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R281e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07487;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0TQ5BmiI_1556065358; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0TQ5BmiI_1556065358) by smtp.aliyun-inc.com(127.0.0.1); Wed, 24 Apr 2019 08:22:48 +0800 Subject: Re: [v2 PATCH] mm: thp: fix false negative of shmem vma's THP eligibility From: Yang Shi To: Michal Hocko Cc: vbabka@suse.cz, rientjes@google.com, kirill@shutemov.name, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1556037781-57869-1-git-send-email-yang.shi@linux.alibaba.com> <20190423175252.GP25106@dhcp22.suse.cz> <6004f688-99d8-3f8c-a106-66ee52c1f0ee@linux.alibaba.com> Message-ID: Date: Tue, 23 Apr 2019 17:22:36 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <6004f688-99d8-3f8c-a106-66ee52c1f0ee@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/23/19 11:34 AM, Yang Shi wrote: > > > On 4/23/19 10:52 AM, Michal Hocko wrote: >> On Wed 24-04-19 00:43:01, Yang Shi wrote: >>> The commit 7635d9cbe832 ("mm, thp, proc: report THP eligibility for >>> each >>> vma") introduced THPeligible bit for processes' smaps. But, when >>> checking >>> the eligibility for shmem vma, __transparent_hugepage_enabled() is >>> called to override the result from shmem_huge_enabled().  It may result >>> in the anonymous vma's THP flag override shmem's.  For example, >>> running a >>> simple test which create THP for shmem, but with anonymous THP >>> disabled, >>> when reading the process's smaps, it may show: >>> >>> 7fc92ec00000-7fc92f000000 rw-s 00000000 00:14 27764 /dev/shm/test >>> Size:               4096 kB >>> ... >>> [snip] >>> ... >>> ShmemPmdMapped:     4096 kB >>> ... >>> [snip] >>> ... >>> THPeligible:    0 >>> >>> And, /proc/meminfo does show THP allocated and PMD mapped too: >>> >>> ShmemHugePages:     4096 kB >>> ShmemPmdMapped:     4096 kB >>> >>> This doesn't make too much sense.  The anonymous THP flag should not >>> intervene shmem THP.  Calling shmem_huge_enabled() with checking >>> MMF_DISABLE_THP sounds good enough.  And, we could skip stack and >>> dax vma check since we already checked if the vma is shmem already. >> Kirill, can we get a confirmation that this is really intended behavior >> rather than an omission please? Is this documented? What is a global >> knob to simply disable THP system wise? >> >> I have to say that the THP tuning API is one giant mess :/ >> >> Btw. this patch also seem to fix khugepaged behavior because it >> previously >> ignored both VM_NOHUGEPAGE and MMF_DISABLE_THP. Second look shows this is not ignored. hugepage_vma_check() would check this for both anonymous vma and shmem vma before scanning. It is called before shmem_huge_enabled(). > > Aha, I didn't notice this. It looks we need separate the patch to fix > that khugepaged problem for both 5.1-rc and LTS. > >> >>> Fixes: 7635d9cbe832 ("mm, thp, proc: report THP eligibility for each >>> vma") >>> Cc: Michal Hocko >>> Cc: Vlastimil Babka >>> Cc: David Rientjes >>> Cc: Kirill A. Shutemov >>> Signed-off-by: Yang Shi >>> --- >>> v2: Check VM_NOHUGEPAGE per Michal Hocko >>> >>>   mm/huge_memory.c | 4 ++-- >>>   mm/shmem.c       | 3 +++ >>>   2 files changed, 5 insertions(+), 2 deletions(-) >>> >>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>> index 165ea46..5881e82 100644 >>> --- a/mm/huge_memory.c >>> +++ b/mm/huge_memory.c >>> @@ -67,8 +67,8 @@ bool transparent_hugepage_enabled(struct >>> vm_area_struct *vma) >>>   { >>>       if (vma_is_anonymous(vma)) >>>           return __transparent_hugepage_enabled(vma); >>> -    if (vma_is_shmem(vma) && shmem_huge_enabled(vma)) >>> -        return __transparent_hugepage_enabled(vma); >>> +    if (vma_is_shmem(vma)) >>> +        return shmem_huge_enabled(vma); >>>         return false; >>>   } >>> diff --git a/mm/shmem.c b/mm/shmem.c >>> index 2275a0f..6f09a31 100644 >>> --- a/mm/shmem.c >>> +++ b/mm/shmem.c >>> @@ -3873,6 +3873,9 @@ bool shmem_huge_enabled(struct vm_area_struct >>> *vma) >>>       loff_t i_size; >>>       pgoff_t off; >>>   +    if ((vma->vm_flags & VM_NOHUGEPAGE) || >>> +        test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) >>> +        return false; >>>       if (shmem_huge == SHMEM_HUGE_FORCE) >>>           return true; >>>       if (shmem_huge == SHMEM_HUGE_DENY) >>> -- >>> 1.8.3.1 >>> >