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[209.85.220.65]) by mx.google.com with SMTPS id h1sor754374ejz.22.2019.05.30.04.14.18 for (Google Transport Security); Thu, 30 May 2019 04:14:18 -0700 (PDT) Received-SPF: neutral (google.com: 209.85.220.65 is neither permitted nor denied by best guess record for domain of kirill@shutemov.name) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@shutemov-name.20150623.gappssmtp.com header.s=20150623 header.b=nFa3Aq2Q; spf=neutral (google.com: 209.85.220.65 is neither permitted nor denied by best guess record for domain of kirill@shutemov.name) smtp.mailfrom=kirill@shutemov.name DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=XNn/kmlHnCSr6ANgnhJMJQoNGplaEoHdHhfpn+42U/U=; b=nFa3Aq2QY1/b/SmZh7j75KjetoNNh4Q4nF7KjkG89Hf33Lzx/kDlxz2Qaxm9vSqVu+ dWKMTXTdpkAf3SlD2sCfX+PWajqNbRsWssTuwLzhMoG+a8MWU/cofO8M+Yq3ZHu7GKiS 4d5eIV53uGfKWdX96tH/kb4YscGd5+m/aiSiYfsOUwTgppVfpXv4x1O3tJM5jNTNArAJ +30E1PCsoPxEbPJnRjT8frtFj5kSYKUlF56xcNYLEju/YnD9uf4z5j+Ybjo9vNYG22fM 3pL263zsGHS7FD+H4sq1/q5Qj1Iy0BbIgmFYjVMUYwkcyvwUksMi4/tpF0Anq+27MwDI WmhQ== X-Google-Smtp-Source: APXvYqzkMPjNWxInx+lzce0w2B8z+OegERN/BaKqbY7ZAOBHZ4GjYaNpaklTSY6DfeQu2yRFAGAiFA== X-Received: by 2002:a17:906:6993:: with SMTP id i19mr2872115ejr.119.1559214858205; Thu, 30 May 2019 04:14:18 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id v22sm383992eji.13.2019.05.30.04.14.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 May 2019 04:14:17 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 4B18C1041ED; Thu, 30 May 2019 14:14:16 +0300 (+03) Date: Thu, 30 May 2019 14:14:16 +0300 From: "Kirill A. Shutemov" To: Song Liu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, namit@vmware.com, peterz@infradead.org, oleg@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, matthew.wilcox@oracle.com, kirill.shutemov@linux.intel.com, kernel-team@fb.com, william.kucharski@oracle.com, chad.mynhier@oracle.com, mike.kravetz@oracle.com Subject: Re: [PATCH uprobe, thp 1/4] mm, thp: allow preallocate pgtable for split_huge_pmd_address() Message-ID: <20190530111416.ph6xqd4anjlm54i6@box> References: <20190529212049.2413886-1-songliubraving@fb.com> <20190529212049.2413886-2-songliubraving@fb.com> <20190530111015.bz2om5aelsmwphwa@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190530111015.bz2om5aelsmwphwa@box> User-Agent: NeoMutt/20180716 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 Thu, May 30, 2019 at 02:10:15PM +0300, Kirill A. Shutemov wrote: > On Wed, May 29, 2019 at 02:20:46PM -0700, Song Liu wrote: > > @@ -2133,10 +2133,15 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, > > VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma); > > VM_BUG_ON(!is_pmd_migration_entry(*pmd) && !pmd_trans_huge(*pmd) > > && !pmd_devmap(*pmd)); > > + /* only file backed vma need preallocate pgtable*/ > > + VM_BUG_ON(vma_is_anonymous(vma) && prealloc_pgtable); > > > > count_vm_event(THP_SPLIT_PMD); > > > > - if (!vma_is_anonymous(vma)) { > > + if (prealloc_pgtable) { > > + pgtable_trans_huge_deposit(mm, pmd, prealloc_pgtable); > > + mm_inc_nr_pmds(mm); > > + } else if (!vma_is_anonymous(vma)) { > > _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd); > > /* > > * We are going to unmap this huge page. So > > Nope. This going to leak a page table for architectures where > arch_needs_pgtable_deposit() is true. And I don't there's correct handling of dirty bit. And what about DAX? Will it blow up? I think so. -- Kirill A. Shutemov