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[209.85.219.179]) by smtp.gmail.com with ESMTPSA id q21-20020a37f715000000b006ed61f18651sm9641786qkj.16.2022.11.08.12.47.00 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Nov 2022 12:47:00 -0800 (PST) Received: by mail-yb1-f179.google.com with SMTP id 129so18729703ybb.12 for ; Tue, 08 Nov 2022 12:47:00 -0800 (PST) X-Received: by 2002:a05:6902:124f:b0:66e:e3da:487e with SMTP id t15-20020a056902124f00b0066ee3da487emr58479884ybu.310.1667940420295; Tue, 08 Nov 2022 12:47:00 -0800 (PST) MIME-Version: 1.0 References: <20221108194139.57604-1-torvalds@linux-foundation.org> <15A1A033-73DC-4ACA-87B0-3535E9236F7F@gmail.com> In-Reply-To: <15A1A033-73DC-4ACA-87B0-3535E9236F7F@gmail.com> From: Linus Torvalds Date: Tue, 8 Nov 2022 12:46:44 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/4] mm: introduce 'encoded' page pointers with embedded extra bits To: Nadav Amit Cc: Hugh Dickins , Johannes Weiner , Andrew Morton , kernel list , linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667940484; 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=M8apV+JQ/XDpdKpjldXGN9Lci+S/grtcg+KJXQEl4jE=; b=ZksKMCsm87vwqudaCiivUHxooiykjRm89EzJ4BKMMGYw8Yn7YB6saSF0pCaQkfGe9RVXd3 61C4YwtH0sFterniBBxdqC2rw16V2+jpHFF5a5RAY3NPSwwcTG5pOttf7KRkdrQi0qrUw5 6seXR8/NnrjaDOwnzgq7GqBgrsm5C0U= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b="B2pLdhd/"; spf=pass (imf09.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.222.181 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667940484; a=rsa-sha256; cv=none; b=mKKXLS3WK5EAZ3Vnm8GARRYiQHc5RolBs5VSgmn19sSTRAi9s4/Wxwg96AA5+9e5rDsWTe NO4I4CiekYFzoMffwhZ38hxSzYxjctQnmAK+wY62TUJdvCSrL0vGqsIjmq0owCxrHibUI1 tVov7HvmHTTiLwpb3Jmr3Uim2x9h5q4= X-Rspam-User: X-Stat-Signature: yeiow4h8j7egi4pgxf4umdoqsq31k1cn X-Rspamd-Queue-Id: 39088140013 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b="B2pLdhd/"; spf=pass (imf09.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.222.181 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org; dmarc=none X-Rspamd-Server: rspam07 X-HE-Tag: 1667940480-816389 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 Tue, Nov 8, 2022 at 12:37 PM Nadav Amit wrote: > > > +static inline bool encoded_page_flags(struct encoded_page *page) > > +{ > > + return ENCODE_PAGE_BITS & (unsigned long)page; > > +} > > I think this one wants to be some unsigned, as otherwise why have > ENCODE_PAGE_BITS as 3ul ? Right you are. That came from my old old version where this was just "bool dirty". Will fix. Doesn't matter for the TLB flushing case, but I really did hope that we could use this for mlock too, and that case needs both bits. I did look at converting mlock (and it's why I wanted to make release_pages() take that whole encoded thing in general, rather than make some special case for it), but the mlock code uses that "struct pagevec" abstraction that seems entirely pointless ("pvec->nr" becomes "pagevec_count(pvec)", which really doesn't seem to be any clearer at alll), but whatever. Linus