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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 271D3C4321E for ; Wed, 30 Nov 2022 23:29:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A88346B0071; Wed, 30 Nov 2022 18:29:16 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A37AC6B0073; Wed, 30 Nov 2022 18:29:16 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 900D26B0074; Wed, 30 Nov 2022 18:29:16 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 7E52D6B0071 for ; Wed, 30 Nov 2022 18:29:16 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 4016A120BB7 for ; Wed, 30 Nov 2022 23:29:16 +0000 (UTC) X-FDA: 80191701912.14.9386676 Received: from mail-yw1-f180.google.com (mail-yw1-f180.google.com [209.85.128.180]) by imf17.hostedemail.com (Postfix) with ESMTP id D522940002 for ; Wed, 30 Nov 2022 23:29:15 +0000 (UTC) Received: by mail-yw1-f180.google.com with SMTP id 00721157ae682-3b5d9050e48so525657b3.2 for ; Wed, 30 Nov 2022 15:29:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=sVGmk8iXfRJi6LHpCkuFJ1XLyGvMWqmOzcPL5P0XpHM=; b=qgKMTJUmPzLXdl3XUPHNLrMjWcbRNKXVr40/b1Cb+68B0JvcoIL+DdetThrvro0I2e Mq3y5U5KHVuJwxTJKuWjfdhdGTB9IZiF6piakctChUJzF4d1ukV3i//n0YzT8bF1UfdK fTYHnjvrlrF1qultVw8XUPzq49LgchZe/fU/zQG+2Dsd0Hpbnhqmzw+21XdStKI2ra30 sZe4lMpAfZTLmSrjd2v5QPu21SzQSsObnFk/0EqFlguUCzBENGfzq30zrzJ34ZmXfrKu G3PYZJL53gDDRrBIhNgaaRKaOtourUk3LB29/ZeHVJfrZpbcreEJ9AMWx/OJNfZjvZSQ H9Zg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=sVGmk8iXfRJi6LHpCkuFJ1XLyGvMWqmOzcPL5P0XpHM=; b=jxQJ5zv+Jo27Tuurl9DPr8G485e2idVQ8y0Rk4HZ4SHIx7Xcn7GnbvIQDptFxewyQD 1YpHdT0pJ3EA4Djk5onAfKu7M28URmWami/ALeKfYTQfLrzNVbZ6i4VDv/X1ZlElnur+ hvIGI4DFJ37669nrpVAAX2X1FcTGua+KTWia33EVBGws6KfQmN/c37mFvfz4F6wfDQ8u Jgb6FDksDOF94YjMLSLVMI4FmJX9ggDr2g1CNX5XiMREAp2Kc//z1l/MVwHlxoqrsRF3 +K4QdEFH06xX9dwt/6GgYZ2nGe34tKy2Hspig+pIDbBg8qDuUABTLqoWys26WHKpJWHi apIw== X-Gm-Message-State: ANoB5plAZaanjqY+ZTAQYliYw2VrL498C30sk67Q3EElfd0PeTXTCbyy WubJyO8nneA8z7GZLhhHQxkBXnjzVQC83wbxiCeCcw== X-Google-Smtp-Source: AA0mqf6oJoBEjEFwNYBRq/FzzoyS0xR2bK87uFIledzCB9j/r6lljZoLVtVbMrE9TynPwRw5fAlVtHAVdGMSn4dHiG4= X-Received: by 2002:a81:4602:0:b0:35f:9c14:144a with SMTP id t2-20020a814602000000b0035f9c14144amr60796886ywa.209.1669850954990; Wed, 30 Nov 2022 15:29:14 -0800 (PST) MIME-Version: 1.0 References: <20221021163703.3218176-1-jthoughton@google.com> <20221021163703.3218176-7-jthoughton@google.com> In-Reply-To: From: James Houghton Date: Wed, 30 Nov 2022 18:29:04 -0500 Message-ID: Subject: Re: [RFC PATCH v2 06/47] hugetlb: extend vma lock for shared vmas To: Peter Xu Cc: Mike Kravetz , Muchun Song , David Hildenbrand , David Rientjes , Axel Rasmussen , Mina Almasry , "Zach O'Keefe" , Manish Mishra , Naoya Horiguchi , "Dr . David Alan Gilbert" , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Baolin Wang , Miaohe Lin , Yang Shi , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1669850955; a=rsa-sha256; cv=none; b=f2OowdgU/2w7qvCWsmnw9WA8Ttjov4le7Aj4MPxvpDODtI3RPRNkHtsQ/ZceQIEFHLD6Nf v0m4yAudwRhsnXYzFUrJGAHEj7Y5Cd5ytZdstDyzF9l4UbsSQz4D2VOLMWyD2EKiHIW0QC SEi9wc8SrrkPSgdDkfX2/s1IkuGJUi8= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=qgKMTJUm; spf=pass (imf17.hostedemail.com: domain of jthoughton@google.com designates 209.85.128.180 as permitted sender) smtp.mailfrom=jthoughton@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1669850955; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sVGmk8iXfRJi6LHpCkuFJ1XLyGvMWqmOzcPL5P0XpHM=; b=6P6uNZYXdbhj0kOLvuD5ttjXC7NJjShuXnNr9AFutDP9/cY5b2yKjX05m68JhPOpKiTPsf YehckgaRj4ckNVCTxPSdTcmc9qWbm4aI/yEq6ETP32w80poDinHFpHBqv7noAZVDLKhRxn gwP62mniACd+a3kNlxHTS6B8qUl4Ptk= X-Stat-Signature: duweehsy4k4431wmntx1g13azsndqq49 X-Rspamd-Queue-Id: D522940002 X-Rspam-User: Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=qgKMTJUm; spf=pass (imf17.hostedemail.com: domain of jthoughton@google.com designates 209.85.128.180 as permitted sender) smtp.mailfrom=jthoughton@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam05 X-HE-Tag: 1669850955-938702 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 Wed, Nov 30, 2022 at 4:01 PM Peter Xu wrote: > > On Fri, Oct 21, 2022 at 04:36:22PM +0000, James Houghton wrote: > > This allows us to add more data into the shared structure, which we will > > use to store whether or not HGM is enabled for this VMA or not, as HGM > > is only available for shared mappings. > > > > It may be better to include HGM as a VMA flag instead of extending the > > VMA lock structure. > > > > Signed-off-by: James Houghton > > --- > > include/linux/hugetlb.h | 4 +++ > > mm/hugetlb.c | 65 +++++++++++++++++++++-------------------- > > 2 files changed, 37 insertions(+), 32 deletions(-) > > > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > > index a899bc76d677..534958499ac4 100644 > > --- a/include/linux/hugetlb.h > > +++ b/include/linux/hugetlb.h > > @@ -121,6 +121,10 @@ struct hugetlb_vma_lock { > > struct vm_area_struct *vma; > > }; > > > > +struct hugetlb_shared_vma_data { > > + struct hugetlb_vma_lock vma_lock; > > +}; > > How about add a comment above hugetlb_vma_lock showing how it should be > used correctly? We lacked documents on the lock for pmd sharing > protections, now if to reuse the same lock for HGM pgtables I think some > doc will definitely help. > > To summarize, I think so far it means: > > - Read lock needed when one wants to stablize VM_SHARED pgtables (covers > both pmd shared pgtables or hgm low-level pgtables) > > - Write lock needed when one wants to release VM_SHARED pgtable pages > (covers both pmd unshare or releasing hgm low-level pgtables) > > Or something like that. Will do. I'll make this change together with the rmap comment update ("rmap: update hugetlb lock comment for HGM"). - James > > -- > Peter Xu >