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 AABA7FAD3EF for ; Thu, 23 Apr 2026 02:37:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1F4756B008A; Wed, 22 Apr 2026 22:37:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 17EAB6B008C; Wed, 22 Apr 2026 22:37:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 045B26B0092; Wed, 22 Apr 2026 22:37:45 -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 E8D106B008A for ; Wed, 22 Apr 2026 22:37:45 -0400 (EDT) Received: from smtpin11.hostedemail.com (lb01b-stub [10.200.18.250]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 86BBC1C0247 for ; Thu, 23 Apr 2026 02:37:45 +0000 (UTC) X-FDA: 84688260090.11.6FFCEC4 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) by imf03.hostedemail.com (Postfix) with ESMTP id 99C0220010 for ; Thu, 23 Apr 2026 02:37:43 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=gxpqvqGO; spf=pass (imf03.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.183 as permitted sender) smtp.mailfrom=baoquan.he@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776911863; a=rsa-sha256; cv=none; b=pRgkyA2Z1Yi9b+RtODrExi560tIkXe79BOW0XTTHUgKxMMj4eucxvke34NQ5mL33myBbaw xJMtVHyWMkMrbphXiYrtELu0+PDprInCaf5TdsJJ/5k6QQ+3+Bk9R/SYoJI2+svHhq73v/ paSoVLOVwRp4RQXqV1x4sMGgRFPcnII= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=gxpqvqGO; spf=pass (imf03.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.183 as permitted sender) smtp.mailfrom=baoquan.he@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776911863; 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=tmDiF8YpdHuzHjKufxDweaNIBD9kEOy5KYDQCBH6Ybs=; b=YU18P7Nvv2RKOSVq6qQiNQyKRLw5SuqoUNc3836Pf0YugCMYanfxoV+ejJLChIRktqak+K ad3ibkkwwW3wYY5piG23teaKi6tNxvB+brJgc/8lucJLgIG7FFGNWFHclikQlpiOym7QJw Lun3k1V6J6nnDQWpmfUe2fh0hD39Bvk= Date: Thu, 23 Apr 2026 10:37:28 +0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1776911859; 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=tmDiF8YpdHuzHjKufxDweaNIBD9kEOy5KYDQCBH6Ybs=; b=gxpqvqGObABR3XmALkCVtRl60wpafyapcdgXLHER2+3286Xx8nYEp1Wk+JCN57xjytirSM QQIoOX3NkhT9Evh5vmtNQuEHQR0nJ4eBq6Q/OJnI89OkRGh94rB+izVxggdc3X/BDfGDsc Jf2brEyoTbedxo1F2P6ZJoVanRRGX00= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Baoquan He To: Chris Li , akpm@linux-foundation.org Cc: linux-mm@kvack.org, usama.arif@linux.dev, baohua@kernel.org, kasong@tencent.com, nphamcs@gmail.com, shikemeng@huaweicloud.com, youngjun.park@lge.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/3] mm/swap: use swap_ops to register swap device's methods Message-ID: References: <20260417033951.1111038-1-baoquan.he@linux.dev> <20260417033951.1111038-3-baoquan.he@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 99C0220010 X-Stat-Signature: isgkjdowdwgi6br976j7a9zpf9nsoyos X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1776911863-188838 X-HE-Meta: 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 CEX0pkkP fLEvEQP5xMkzAwS1pk2rGCUVe00CjBgnpe/d6vpMZV61XIV3sQALisrV7fQ+yw/TUiaUznByHW32BrFB8zTnV5SQPyuaGrTgSOMQexZ+FIYS0MvQjZ+tlgKgLuMhFT6nK5SRSItY5Kg8v68TX/nTubATTHee7Ob/h6RKw+rqMZ0nZAR6uPY4LnSXllCN4eXh1WMOCATPKiqg/7jO0N/tlL7J3390B+KrXkkCSo+q8Z1JhBUqrYdybL3yWLurfa65kuxmWReQfS6+Sc8F2UOpXE8KqlcM4DhCOtb3ERbpZTnZ0q+XnVKM9BZOYM1lM6E3cVilM Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 04/22/26 at 05:33pm, Chris Li wrote: > On Tue, Apr 21, 2026 at 6:48 PM Baoquan He wrote: > > > > On 04/17/26 at 07:30pm, Chris Li wrote: > > > On Thu, Apr 16, 2026 at 8:40 PM Baoquan He wrote: > > ...snip... > > > > +int init_swap_ops(struct swap_info_struct *sis) > > > > +{ > > > > + /* > > > > + * ->flags can be updated non-atomically, but that will > > > > + * never affect SWP_FS_OPS, so the data_race is safe. > > > > + */ > > > > + if (data_race(sis->flags & SWP_FS_OPS)) > > > > + sis->ops = &bdev_fs_swap_ops; > > > > + /* > > > > + * ->flags can be updated non-atomically, but that will > > > > + * never affect SWP_SYNCHRONOUS_IO, so the data_race is safe. > > > > + */ > > > > + else if (data_race(sis->flags & SWP_SYNCHRONOUS_IO)) > > > > + sis->ops = &bdev_sync_swap_ops; > > > > + else > > > > + sis->ops = &bdev_async_swap_ops; > > > > + > > > > + if (!sis->ops || !sis->ops->read_folio || !sis->ops->write_folio) > > > > + return -1; > > > Nitpick: > > > > > > For int type error return, you should use -EINVAL or some thing with > > > error code. If you don't care about error code, change the return type > > > to bool instead. > > > > Thanks for careful reviewing, returning -EINVAL looks better, I will > > change like that and repost. > > You don't have to repost it as a new series. You can post one small > incremental update for the -EINVAL change and ask Andrew to fold it > in. > > Hi Andrew, > > I think this swap ops series can be merge to mm-unstable with the > review. Keep in mind that Baoquan might have a very minor follow up > patch relate to -EINAL error code. The incremental update is as below. I have built and test it. diff --git a/mm/swap_io.c b/mm/swap_io.c index 77aa8373c087..e2710d5fb44e 100644 --- a/mm/swap_io.c +++ b/mm/swap_io.c @@ -625,7 +625,7 @@ int init_swap_ops(struct swap_info_struct *sis) sis->ops = &bdev_async_swap_ops; if (!sis->ops || !sis->ops->read_folio || !sis->ops->write_folio) - return -1; + return -EINVAL; return 0; } diff --git a/mm/swapfile.c b/mm/swapfile.c index af81fa212f1e..7644049a0919 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -3518,10 +3518,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) goto bad_swap_unlock_inode; } - if (init_swap_ops(si)) { - error = -EINVAL; + if (error = init_swap_ops(si)) goto bad_swap_unlock_inode; - } si->max = maxpages; si->pages = maxpages - 1;