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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 336F7C79F89 for ; Mon, 7 Sep 2026 12:34:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 551FB6B009E; Mon, 7 Sep 2026 08:33:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 503EB6B009F; Mon, 7 Sep 2026 08:33:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3F4166B00A0; Mon, 7 Sep 2026 08:33:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 1E4226B009E for ; Mon, 7 Sep 2026 08:33:59 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id AE38580152 for ; Mon, 7 Sep 2026 12:33:58 +0000 (UTC) X-FDA: 85186908156.06.BD24929 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf27.hostedemail.com (Postfix) with ESMTP id F27F940013 for ; Mon, 7 Sep 2026 12:33:56 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=AHJmmyOp; spf=pass (imf27.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788784437; 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=h7cKBm7+BzUzCvCkEH7tyBUTdRm4vS9wwDEbS3sNZuE=; b=zzaOvEZotqCVE91cdLR1uHGoci/c6F1QtJUbqMZqQuNv3dw5SldtsstTa0feU2IQavjKLk Tw9trCz8ZZN2ZYYVX9zJ/iwsbJhtxFtEyVGdErZuun5zPqe7K07YvUhZIUlNreQGleWRwl AzIpBGkunAEydkiY2mMzcOlGE1MNiAo= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788784437; b=Y3gZ8b2ZgnL+hjZ40hsprqGr+j8ET4s9J8ctWPETIyhPd4wtpkiC5oKCz63yK0QBROCnG/ Pbbh2ZXVDli5mH31dP9EHz4yS4xbEZ6yakF+aoAkCuxwGDwjgjzBwOAbNEe8/A3tcuAWXu udWKzVor+H28onXVLvjo3syEvZO0WWI= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=AHJmmyOp; spf=pass (imf27.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 506D642337; Mon, 7 Sep 2026 12:33:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEDA01F00A3E; Mon, 7 Sep 2026 12:33:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788784436; bh=h7cKBm7+BzUzCvCkEH7tyBUTdRm4vS9wwDEbS3sNZuE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=AHJmmyOpiwExIz4vREZk9fQD+t6Q8jCuI00q/MyLSuDZHHaQBS4ygHbC7AtSWZQ8T J2FVEopbouH1yFG1kPLeu0k0diRmQDZIC537aX83zKcO1lQ4juKPm00ZLTrFX1Cjy2 BNPfO+W+r/r1dBaIdJEkakAPZebE7tbiNCxeXG6GFUL3KlPDkLcKZYSFCBW5dWfDtt sOkDMNIFcoEzc+bj0u2OQ+9hmXrMAak1hJc1br0aFcvLkChengGjrWQh/peJX1SKTE aMWSeREzzHNLg+WYLTLtDgI42cJmb4uEgWccSuQnAepxBPJY5lQZ4lsWoeR/CMPVR4 GydJS25pRlFqA== Date: Mon, 7 Sep 2026 13:33:51 +0100 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Pedro Falcato , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Kaplinskiy , zhaozhengzhuo Subject: Re: [PATCH] mm/madvise: swap in CoW'd MAP_PRIVATE-file mappings on MADV_WILLNEED Message-ID: References: <20260904-madv-will-need-map-private-v1-1-6b83cc99fcff@kernel.org> <5930324d-8252-42e1-ad50-aab796e41550@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5930324d-8252-42e1-ad50-aab796e41550@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: F27F940013 X-Stat-Signature: stwswwrrnbfy95jhjfn7n3u4u3uctrtz X-HE-Tag: 1788784436-1229 X-HE-Meta: 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 qVoBneKT xYgE+ibhQr/ctxOJD5fhYgkzaCT02rmMH7l06fvqTsciftC5itaQ2qfVde8kqSoSIBqzMITUpwrnROaIxWpbgBjzGT5vFJQjI2yWXyHyejmdJn3YDG96IAOfUm1rNA5OoEdErVaKe0iSczAcEf6c7nGFQUntCQLOOLb7MI52PWm5kuhFGOl5JivtzSOqvMdede7awNd3T13MhOXvUweroVvRi1Ylj8TLQ43U/c7PYhgUCg1dQMV3XiUQYkw7gYggS7pB7OBr5DpsbP/ztEd+PdvZnMWRMSTCthbUStSRaS82sI0dJ0TqKvXSb4cL3iaSyz/zeavE6gaGe1zbWHmhOEK0kofDMy55inXFg Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 07, 2026 at 01:51:20PM +0200, David Hildenbrand (Arm) wrote: > > And it's a real improvement to have unfaulted anon skip... > > > > But I find that version is documenting what's going on a lot less. > > > > Since both anon and MAP_PRIVATE file-backed are CoW mappings we could just > > reference that. > > > > Andrew - could you swap the patch out in-place with below? Thanks! > > A proper v2 would have been nice ;) > > (and would trigger sashiko and friends properly) Ack, though it's kinda obviously functionally equivalent (or so I felt :P). I had a local LLM check it FWIW. > > > > > Cheers, Lorenzo > > > > ----8<---- > > From a706374a1186b6b4409a0e760e8728bcadba0c96 Mon Sep 17 00:00:00 2001 > > From: "Lorenzo Stoakes (ARM)" > > Date: Thu, 3 Sep 2026 20:08:39 +0100 > > Subject: [PATCH] mm/madvise: swap in CoW'd MAP_PRIVATE-file mappings on > > MADV_WILLNEED > > > > Currently MADV_WILLNEED treats file-backed and pure anonymous mappings > > entirely separately - using POSIX_FADV_WILLNEED (equivalent of a readahead) > > for the former and a tree walk and swap in to swap cache for the latter. > > > > MAP_PRIVATE-file backed mappings straddle the two and currently get treated > > as if they were purely file-backed, meaning any swapped out private pages > > remain swapped out. > > > > Resolve the issue by explicitly checking for CoW'd MAP_PRIVATE-file backed > > mappings and performing both walks in this case. > > > > Since the logic checks for vma->anon_vma this means un-CoW'd > > MAP_PRIVATE-file backed mappings retain only the single file walk. > > > > Reported-by: Mike Kaplinskiy > > Closes: https://lore.kernel.org/all/CABeknB_S2XJSHFgnHdgnN0rjzHhH4oQJs_APq9fvxHztQ_pgiA@mail.gmail.com/ > > Signed-off-by: Lorenzo Stoakes (ARM) > > --- > > mm/madvise.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/mm/madvise.c b/mm/madvise.c > > index 73c2901b9adb..963337f93a7a 100644 > > --- a/mm/madvise.c > > +++ b/mm/madvise.c > > @@ -297,11 +297,12 @@ static long madvise_willneed(struct madvise_behavior *madv_behavior) > > loff_t offset; > > > > #ifdef CONFIG_SWAP > > - if (!file) { > > + if (vma_is_cow_mapping(vma) && vma->anon_vma) { > > walk_page_range_vma(vma, start, end, &swapin_walk_ops, vma); > > lru_add_drain(); /* Push any new pages onto the LRU now */ > > - return 0; > > } > > + if (!file) > > + return 0; > > > LGTM > > Acked-by: David Hildenbrand (Arm) Thanks! > > -- > Cheers, > > David -- Cheers, Lorenzo