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 090E3CD4F35 for ; Tue, 12 May 2026 07:08:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6B80C6B008A; Tue, 12 May 2026 03:08:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 668AE6B008C; Tue, 12 May 2026 03:08:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 57ECA6B0092; Tue, 12 May 2026 03:08:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 488556B008A for ; Tue, 12 May 2026 03:08:45 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 7A37EA03B5 for ; Tue, 12 May 2026 07:08:44 +0000 (UTC) X-FDA: 84757890168.06.D380A1D Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf12.hostedemail.com (Postfix) with ESMTP id 9F15E4000C for ; Tue, 12 May 2026 07:08:42 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=AZVW7Qui; spf=pass (imf12.hostedemail.com: domain of dlemoal@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=dlemoal@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=1778569722; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+1g2BYrxNdHvMG4oS1gqg4AFd7Dh4ZSvU4RmIUkVh/8=; b=6zABFa+CqEgREHIzjcW550cVvFJIp9hyHmPW+XqH86D1u9M4jeY/fOqGmisTv1YCe9Mkt8 8Vj2NwOgsEmZrlymkXTSyrhXDL8YYRKJvY1qArcXA6MtqDTHlLFgKmIDfEOsYM8e706n77 DEEox/5LaoST0VNJIQhgihcWKX/LAWo= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1778569722; a=rsa-sha256; cv=none; b=yqh8WIt84xT3+MZQgelNXJyK8+j077dO2d8cKBhu7ixwD0iaL4ht07Lu377C279wL8DDf1 JW8KOHo2DDIbj7IygomvJdmYxbLBoMdEIcZCDM6+S6kpGlN7mQ95OP5Xfwr4OUCUZV89Oq dp7Bq6mdDGMbSwUCZSCyL4Ef1IKO9dA= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=AZVW7Qui; spf=pass (imf12.hostedemail.com: domain of dlemoal@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=dlemoal@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 842BA440E1; Tue, 12 May 2026 07:08:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E6A5C2BCFD; Tue, 12 May 2026 07:08:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778569721; bh=5R+EGY533uqCmLzbRat4246szQJrvxiGXh+zrcNZP8Y=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=AZVW7Qui1CP12PCsES+DAfGefhgG6ZsGG+IPd29OfkaPW+1CkthidE8AZJwY75U0C 4rNrhnRBljNrhbvZDbEiEgSRDdXMcjdraEcCwuiJdxsOXLKnGqhSVmrr/6hhPR2x9L 5vwiYRzb+7Elk2tmObpq81hcArgCm9ZegwZDJEAkv9M9iicfMeRn5NaRYpNZWqfPOE 2HWszZ/4Gxf/5HGNX9W/seayQBqvEPgMe4Hs7m6wvAkzGhJbO9TvFDGMPWP3Yn5FY9 SZ27OhjGJ/CoGsGG5mf9JCFTzQ3uplWm0vr4OAI+NqYEiilCS2Y4tpjuYjp3Qie9BH /RQBnxU6ladzQ== Message-ID: <03dddf72-8755-4ebf-ba79-456377f0f25d@kernel.org> Date: Tue, 12 May 2026 16:08:35 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 01/12] swap: remove the maxpages variable in sys_swapon To: Christoph Hellwig , Andrew Morton , Chris Li , Kairui Song Cc: Christian Brauner , "Darrick J . Wong" , Jens Axboe , David Sterba , Theodore Ts'o , Jaegeuk Kim , Chao Yu , Trond Myklebust , Anna Schumaker , Namjae Jeon , Hyunchul Lee , Steve French , Paulo Alcantara , Carlos Maiolino , Naohiro Aota , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org References: <20260512053625.2950900-1-hch@lst.de> <20260512053625.2950900-2-hch@lst.de> Content-Language: en-US From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <20260512053625.2950900-2-hch@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 9F15E4000C X-Rspam-User: X-Stat-Signature: snws4i33s6rd97zg5h5zdrckp13n684p X-HE-Tag: 1778569722-986834 X-HE-Meta: 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 dy2a2yYP nsusuOeSOM3RI2wyqQtrHMeaNfTn7i7VFqbCQzgQoGP6gXGZL2N2BwRgh4qjVK3seKeyT3t/03WXzYWAaI9OXVpp2kxpNilA+jTHr5PlBuwYKyK7GnYOrZo04h3Zwy8dbvqApu6xHi/Xx3nkw2U4/FSq/dhNNepxQVAT4vjWv83dzbQtnwhdyo+XPAR4JVhxnm2EQyXKk5KJ0UFlG6Xf+CSkfzcJy4EFBteUOj/J1EYHPBmz1kXGp8Ymh18tTTe6uMpQOwqcXH71u2BFsSMx3yGvDoDKYGe2+q62k7+0AOlAlAVazQjvGe1pZ8l9KaCVx0kXk9KK/KY5NIY/WiSyy4ZbNg3JtTBuaUbjO3xwD3dX6Mxc/76aUvL/6LuSPElTxK46dujrFKtFigSGjnOzq4Vnsq4oG2hZtOye1 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/12/26 14:35, Christoph Hellwig wrote: > Always use si->max which is updated setup_swap_extents instead of copying > into and out of maxpages. Checking mm/swapfile.c, I see s->max being set only in swapon(). Is this a typo or am I misunderstanding this sentence ? Looks good otherwise, but it would be nice to rename ->max to ->maxpages to make it clear what this is counting. > > Signed-off-by: Christoph Hellwig > --- > mm/swapfile.c | 27 +++++++++++---------------- > 1 file changed, 11 insertions(+), 16 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 9174f1eeffb0..f7ebd97e28a3 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -3350,10 +3350,9 @@ static unsigned long read_swap_header(struct swap_info_struct *si, > } > > static int setup_swap_clusters_info(struct swap_info_struct *si, > - union swap_header *swap_header, > - unsigned long maxpages) > + union swap_header *swap_header) > { > - unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); > + unsigned long nr_clusters = DIV_ROUND_UP(si->max, SWAPFILE_CLUSTER); > struct swap_cluster_info *cluster_info; > int err = -ENOMEM; > unsigned long i; > @@ -3395,7 +3394,7 @@ static int setup_swap_clusters_info(struct swap_info_struct *si, > if (err) > goto err; > } > - for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) { > + for (i = si->max; i < round_up(si->max, SWAPFILE_CLUSTER); i++) { > err = swap_cluster_setup_bad_slot(si, cluster_info, i, true); > if (err) > goto err; > @@ -3425,7 +3424,7 @@ static int setup_swap_clusters_info(struct swap_info_struct *si, > si->cluster_info = cluster_info; > return 0; > err: > - free_swap_cluster_info(cluster_info, maxpages); > + free_swap_cluster_info(cluster_info, si->max); > return err; > } > > @@ -3440,7 +3439,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > union swap_header *swap_header; > int nr_extents; > sector_t span; > - unsigned long maxpages; > struct folio *folio = NULL; > struct inode *inode = NULL; > bool inced_nr_rotate_swap = false; > @@ -3512,14 +3510,13 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > } > swap_header = kmap_local_folio(folio, 0); > > - maxpages = read_swap_header(si, swap_header, inode); > - if (unlikely(!maxpages)) { > + si->max = read_swap_header(si, swap_header, inode); > + if (unlikely(!si->max)) { > error = -EINVAL; > goto bad_swap_unlock_inode; > } > > - si->max = maxpages; > - si->pages = maxpages - 1; > + si->pages = si->max - 1; > nr_extents = setup_swap_extents(si, swap_file, &span); > if (nr_extents < 0) { > error = nr_extents; > @@ -3531,14 +3528,12 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > goto bad_swap_unlock_inode; > } > > - maxpages = si->max; > - > /* Set up the swap cluster info */ > - error = setup_swap_clusters_info(si, swap_header, maxpages); > + error = setup_swap_clusters_info(si, swap_header); > if (error) > goto bad_swap_unlock_inode; > > - error = swap_cgroup_swapon(si->type, maxpages); > + error = swap_cgroup_swapon(si->type, si->max); > if (error) > goto bad_swap_unlock_inode; > > @@ -3546,7 +3541,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > * Use kvmalloc_array instead of bitmap_zalloc as the allocation order might > * be above MAX_PAGE_ORDER incase of a large swap file. > */ > - si->zeromap = kvmalloc_array(BITS_TO_LONGS(maxpages), sizeof(long), > + si->zeromap = kvmalloc_array(BITS_TO_LONGS(si->max), sizeof(long), > GFP_KERNEL | __GFP_ZERO); > if (!si->zeromap) { > error = -ENOMEM; > @@ -3597,7 +3592,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > } > } > > - error = zswap_swapon(si->type, maxpages); > + error = zswap_swapon(si->type, si->max); > if (error) > goto bad_swap_unlock_inode; > -- Damien Le Moal Western Digital Research