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 D298CC433EF for ; Tue, 8 Mar 2022 17:30:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5EBB48D000C; Tue, 8 Mar 2022 12:30:34 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 59A808D0001; Tue, 8 Mar 2022 12:30:34 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 464648D000C; Tue, 8 Mar 2022 12:30:34 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 384D18D0001 for ; Tue, 8 Mar 2022 12:30:34 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 054068205B for ; Tue, 8 Mar 2022 17:30:34 +0000 (UTC) X-FDA: 79221908388.01.0BC75E5 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf27.hostedemail.com (Postfix) with ESMTP id 703264000E for ; Tue, 8 Mar 2022 17:30:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1646760632; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RrQZONKH8fANjG8V+2cdfnG5GYSQ2J7Zzmc69wjh+wI=; b=Fl6osehaoyzLTkPMarP5Z7RmWftkJMo95XxRmrBs3+R4jZrnlxL7ajK07GYBKVKRcjEou5 cSw9IvFA0Ucsyc3sKt/ADsI9WF5jql5xRvngRrQVDH7/WxSkYQKwadbpPky3d+rfEiWbIu +AG44tu3Qx601EY/Cn8chjxFfuBr6Ig= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-6-76WTKwkOPeG59xZSsOI4Ug-1; Tue, 08 Mar 2022 12:30:31 -0500 X-MC-Unique: 76WTKwkOPeG59xZSsOI4Ug-1 Received: by mail-wr1-f71.google.com with SMTP id x15-20020a5d6b4f000000b001ee6c0aa287so5708559wrw.9 for ; Tue, 08 Mar 2022 09:30:31 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent :content-language:to:cc:references:from:organization:subject :in-reply-to:content-transfer-encoding; bh=RrQZONKH8fANjG8V+2cdfnG5GYSQ2J7Zzmc69wjh+wI=; b=nOW84wfqPF3HvdOz3PqzSZRmezl2j+jvNAzbX+OTQbwqar6Lolvlm57TiGF+RFUYY5 XD5ke85Pp3elzMygb/B2yuy1rcN52uzk+Mt5N6Mftlp1k9zx8d1JgKZhCC16CzJmx734 +lOumc2GTX3yE7OqJ0GT5b83O17UK8nS7bICVhHzC/KB/yZ0f8FVxAwXonNKkqoYzGS6 y+z1EiZ2/ssSVUAwMSmQJkKK7UxY+frBbApkf+uqvpT3ESVxPtFfcG2UYSm6q0idNpeP mzF3OMl4e8K5qFM8vrvoUSXeis7Wc3gNwjw/ipLSuBFM6O6nSGg+z1Ki7RaiEFtg0E9E IZwg== X-Gm-Message-State: AOAM533DtTGoUyTKtEOX6Tk90cyuBG0J6KnQimz0xZLbRB8XVRppoLw9 xFF/SahMrb0AC5V9lU5xuKboIWfXeH48qCkXpL5pfDypjryBtD4jT8i71ss49N4mF3+ApqBZm9P yLTWlIkxRqTQ= X-Received: by 2002:a05:6000:1ca:b0:1f0:2480:f52a with SMTP id t10-20020a05600001ca00b001f02480f52amr12482338wrx.388.1646760630576; Tue, 08 Mar 2022 09:30:30 -0800 (PST) X-Google-Smtp-Source: ABdhPJzDAENBQc1zP8ZSIn+WSmfhqum7CTY69wlNEUhRmwNIuvNPsivAMbIoVqdXHnVzYYAoZMymqg== X-Received: by 2002:a05:6000:1ca:b0:1f0:2480:f52a with SMTP id t10-20020a05600001ca00b001f02480f52amr12482301wrx.388.1646760630248; Tue, 08 Mar 2022 09:30:30 -0800 (PST) Received: from ?IPV6:2003:cb:c708:b000:acda:b420:16aa:6b67? (p200300cbc708b000acdab42016aa6b67.dip0.t-ipconnect.de. [2003:cb:c708:b000:acda:b420:16aa:6b67]) by smtp.gmail.com with ESMTPSA id p11-20020adf9d8b000000b001f063deef80sm12426128wre.86.2022.03.08.09.30.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Mar 2022 09:30:29 -0800 (PST) Message-ID: Date: Tue, 8 Mar 2022 18:30:28 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 To: Nadav Amit Cc: Linux Kernel Mailing List , Andrew Morton , Hugh Dickins , Linus Torvalds , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Liang Zhang , Pedro Gomes , Oded Gabbay , "linux-mm@kvack.org" References: <20220308141437.144919-1-david@redhat.com> <20220308141437.144919-6-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v1 05/15] mm/rmap: convert RMAP flags to a proper distinct rmap_t type In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 703264000E X-Stat-Signature: k9d1wb5qmpmwnzxpdczpq5zzemko9r8f X-Rspam-User: Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Fl6oseha; spf=none (imf27.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam07 X-HE-Tag: 1646760633-883082 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 08.03.22 18:15, Nadav Amit wrote: > > >> On Mar 8, 2022, at 6:14 AM, David Hildenbrand wrote: >> >> We want to pass the flags to more than one anon rmap function, getting >> rid of special "do_page_add_anon_rmap()". So let's pass around a distinct >> __bitwise type and refine documentation. >> >> Signed-off-by: David Hildenbrand >> --- >> include/linux/rmap.h | 22 ++++++++++++++++++---- >> mm/memory.c | 6 +++--- >> mm/rmap.c | 7 ++++--- >> 3 files changed, 25 insertions(+), 10 deletions(-) >> >> diff --git a/include/linux/rmap.h b/include/linux/rmap.h >> index 92c3585b8c6a..49f6b208938c 100644 >> --- a/include/linux/rmap.h >> +++ b/include/linux/rmap.h >> @@ -158,9 +158,23 @@ static inline void anon_vma_merge(struct vm_area_struct *vma, >> >> struct anon_vma *page_get_anon_vma(struct page *page); >> >> -/* bitflags for do_page_add_anon_rmap() */ >> -#define RMAP_EXCLUSIVE 0x01 >> -#define RMAP_COMPOUND 0x02 >> +/* RMAP flags, currently only relevant for some anon rmap operations. */ >> +typedef int __bitwise rmap_t; >> + >> +/* >> + * No special request: if the page is a subpage of a compound page, it is >> + * mapped via a PTE. The mapped (sub)page is possibly shared between processes. >> + */ >> +#define RMAP_NONE ((__force rmap_t)0) >> + >> +/* The (sub)page is exclusive to a single process. */ >> +#define RMAP_EXCLUSIVE ((__force rmap_t)BIT(0)) >> + >> +/* >> + * The compound page is not mapped via PTEs, but instead via a single PMD and >> + * should be accounted accordingly. >> + */ >> +#define RMAP_COMPOUND ((__force rmap_t)BIT(1)) > Hi Nadav, > I was once shouted at for a similar suggestion, but I am going to try > once more… If you already define a new type, why not to use bitfields? I don't have a strong opinion, however, I'd prefer keeping it consistent with existing ways of passing flags. Personally, I like __bitwise because it just behave the way we're used to pass flags -- with additional type safety. Especially once eventually passing many flags (like we do with GFP), bitfields might turn out rather nasty -- IMHO. Thanks! -- Thanks, David / dhildenb