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 C9DEBC282EC for ; Thu, 6 Mar 2025 23:42:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3E30B280004; Thu, 6 Mar 2025 18:42:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 39243280002; Thu, 6 Mar 2025 18:42:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 282A1280004; Thu, 6 Mar 2025 18:42:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 0ADAC280002 for ; Thu, 6 Mar 2025 18:42:18 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 51D59C0B73 for ; Thu, 6 Mar 2025 23:42:20 +0000 (UTC) X-FDA: 83192752440.24.5375DBF Received: from out-187.mta0.migadu.com (out-187.mta0.migadu.com [91.218.175.187]) by imf29.hostedemail.com (Postfix) with ESMTP id 8EE59120006 for ; Thu, 6 Mar 2025 23:42:18 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bSNq+nD1; spf=pass (imf29.hostedemail.com: domain of yosry.ahmed@linux.dev designates 91.218.175.187 as permitted sender) smtp.mailfrom=yosry.ahmed@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=1741304538; 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=fU6cPBemXEC5vkZEvT/CCIy/jzWhHpo6npFWGn/8iRI=; b=QvMjbsy8ynrQ7zl+p6zVqHM09juC9ozs6FeewITnHc6R+e0OF3PLYFsqmoY11ugFloVhq2 G6GIp7rC1pPIW6FZnHvPuGDd9sJcQLIxTxwBIceoE+9vcB0g+KOyQDdHanHatxwZkhKQwu OYOTPO4YChKcBZ/MK2lYQyQmlcPgXao= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=bSNq+nD1; spf=pass (imf29.hostedemail.com: domain of yosry.ahmed@linux.dev designates 91.218.175.187 as permitted sender) smtp.mailfrom=yosry.ahmed@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1741304538; a=rsa-sha256; cv=none; b=qod20GrEBfw5qKfrtDPObnrGgtKvNc8NUMRpDT/vyYD3h2Yqzp2PoNTwgCOP+lEyQAqoEt 4R5FEfqgYhhA701MJM/6qCqhru7nLNHFpW4cBgdQ5GOwc44X7ysEzwQ89I/XqdDcFByoya wl7DLo9iSCoG/aPg7gYsI0Tijj4nhGA= Date: Thu, 6 Mar 2025 23:42:08 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1741304534; 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: in-reply-to:in-reply-to:references:references; bh=fU6cPBemXEC5vkZEvT/CCIy/jzWhHpo6npFWGn/8iRI=; b=bSNq+nD1O3vZsgkjn7awJJ37l2cfr7+cFXTCbKGFr854zjuC25z94Ey3ogM7Nwvj5hnuB+ wa1rA4qoXjZTxqL1Eadkf1PdzqrSQn2LWuqUt3o6koSmCVbSG/9j4SOhLOo5mpL92/BFHQ 8AOOM2y3mFvAYh0rOi217HSy2TSW/Lw= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yosry Ahmed To: Nhat Pham Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, chengming.zhou@linux.dev, linux-mm@kvack.org, kernel-team@meta.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] page_io: return proper error codes for swap_read_folio_zeromap() Message-ID: References: <20250306230015.1456794-1-nphamcs@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250306230015.1456794-1-nphamcs@gmail.com> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Stat-Signature: q9yk8zc5uj66x95d8koz6goq5q64pbog X-Rspamd-Queue-Id: 8EE59120006 X-Rspamd-Server: rspam07 X-HE-Tag: 1741304538-322714 X-HE-Meta: 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 aTkb+IIX HrmerPIfnAlRsbG4XRYD8w+tb80qKNx6lvS2abG+Y9r/Qa/CHKyTFm8AzenxJ475zPDdWqlKd5/qS5xkUelTPDpMO8YJNEDbjeuaaxVYI/yFj1C1FjKH3CaS5Xs9xblMCnmX8aMZ3orD9DL6jwaW8VYFZ8EqmPslHC1KhWtjVs5GRb0ObjrRLehdP0+UE14G/H0V0+VpMw4pDNHA9GNB5wsKEP0wK5sXpKt91fZEcLEFuJ2YtPonpDIPv/RdOm6Wf2hTmsvzu6zy12RsWNP9u0o/LJWNCEFN6I+9/r0JDjCl/K2b2NvNj35lOUBmZrv9IwIINXY20wPN3rBiCnqJyRzoSrHXiQ92lGaki80d/KLwgXoXafI8dRgz8BA== 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: List-Subscribe: List-Unsubscribe: On Thu, Mar 06, 2025 at 03:00:15PM -0800, Nhat Pham wrote: > Similar to zswap_load(), also return proper error codes for > swap_read_folio_zeromap(): > > * 0 on success. The folio is unlocked and marked up-to-date. > * -ENOENT, if the folio is entirely not zeromapped. > * -EINVAL (with the follio unlocked but not marked to date), if the > folio is partially zeromapped. This is not supported, and will SIGBUS > the faulting process. > > This patch is purely a clean-up, and should not have any behavioral > change. It is based on (and should be applied on top of) [1]. > > [1]: https://lore.kernel.org/linux-mm/20250306205011.784787-1-nphamcs@gmail.com/ > > Suggested-by: Yosry Ahmed > Suggested-by: Johannes Weiner > Signed-off-by: Nhat Pham > --- > mm/page_io.c | 35 ++++++++++++++++++++++++++--------- > 1 file changed, 26 insertions(+), 9 deletions(-) > > diff --git a/mm/page_io.c b/mm/page_io.c > index 4bce19df557b..48ed1e810392 100644 > --- a/mm/page_io.c > +++ b/mm/page_io.c > @@ -511,7 +511,23 @@ static void sio_read_complete(struct kiocb *iocb, long ret) > mempool_free(sio, sio_pool); > } > > -static bool swap_read_folio_zeromap(struct folio *folio) > +/** > + * swap_read_folio_zeromap - check if the folio was zeromapped, and if so, > + * zero-fill it. > + * @folio: the folio. > + * > + * Return: 0 on success, with the folio zero-filled, unlocked, and marked > + * up-to-date, or one of the following error codes: > + * > + * -ENOENT: the folio is entirely not zeromapped. The folio remains locked. > + * > + * -EINVAL: some of the subpages in the folio are zeromaped, but not all of > + * them. This is an error because we don't currently support a large folio > + * that is partially in the zeromap. The folio is unlocked, but NOT marked > + * up-to-date, so that an IO error is emitted (e.g. do_swap_page() will > + * sigbus). This is a bit repetitive. Maybe: * -EINVAL: The folio is partially in the zeromap, which is not * currently supported. The folio is unlocked, but NOT marked * up-to-date, so that an IO error is emitted (e.g. do_swap_page() will * sigbus). > + */ > +static int swap_read_folio_zeromap(struct folio *folio) > { > int nr_pages = folio_nr_pages(folio); > struct obj_cgroup *objcg; > @@ -519,15 +535,17 @@ static bool swap_read_folio_zeromap(struct folio *folio) > > /* > * Swapping in a large folio that is partially in the zeromap is not > - * currently handled. Return true without marking the folio uptodate so > + * currently handled. Return -EINVAL without marking the folio uptodate so > * that an IO error is emitted (e.g. do_swap_page() will sigbus). > */ I would drop this whole comment now because it's mostly repeating what's now documneted above. With the comments fixed up: Reviewed-by: Yosry Ahmed > if (WARN_ON_ONCE(swap_zeromap_batch(folio->swap, nr_pages, > - &is_zeromap) != nr_pages)) > - return true; > + &is_zeromap) != nr_pages)) { > + folio_unlock(folio); > + return -EINVAL; > + } > > if (!is_zeromap) > - return false; > + return -ENOENT; > > objcg = get_obj_cgroup_from_folio(folio); > count_vm_events(SWPIN_ZERO, nr_pages); > @@ -538,7 +556,8 @@ static bool swap_read_folio_zeromap(struct folio *folio) > > folio_zero_range(folio, 0, folio_size(folio)); > folio_mark_uptodate(folio); > - return true; > + folio_unlock(folio); > + return 0; > } > > static void swap_read_folio_fs(struct folio *folio, struct swap_iocb **plug) > @@ -635,10 +654,8 @@ void swap_read_folio(struct folio *folio, struct swap_iocb **plug) > } > delayacct_swapin_start(); > > - if (swap_read_folio_zeromap(folio)) { > - folio_unlock(folio); > + if (swap_read_folio_zeromap(folio) != -ENOENT) > goto finish; > - } > > if (zswap_load(folio) != -ENOENT) > goto finish; > -- > 2.43.5 >