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 25AB8C021BB for ; Mon, 24 Feb 2025 15:33:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 71A916B007B; Mon, 24 Feb 2025 10:33:36 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A3FC6B0082; Mon, 24 Feb 2025 10:33:36 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 544426B0083; Mon, 24 Feb 2025 10:33:36 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 356E96B007B for ; Mon, 24 Feb 2025 10:33:36 -0500 (EST) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id BD7D01A1527 for ; Mon, 24 Feb 2025 15:33:35 +0000 (UTC) X-FDA: 83155232790.11.4DDFF00 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf14.hostedemail.com (Postfix) with ESMTP id 8711A100020 for ; Mon, 24 Feb 2025 15:33:32 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=XgmiQpUP; spf=none (imf14.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1740411214; 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=2kZuikH82YSc7S3HfNANRsQo2YtDaV4SIY3/Jou1Rhs=; b=ZBhJ9NjgUHGOgC4ZCZ3weqHM/XXo03yu0kQ+pcj4HMJwB9f8GiXNPbzBu12FgstWkK+JOE LtGIzn7qMwccHJDfd4XNr9uQw6e/5s8p1uh14U5xBwIbet3iz2j7fGhUYsdDjc6mSADctj rPkJnP6bpbzHfx9S4ZoQWljyWP6ZWYs= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=XgmiQpUP; spf=none (imf14.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1740411214; a=rsa-sha256; cv=none; b=nNuMTrAaOMUCbmCCXlrIUmcaZp7QO1Wf4XE7wPUoBO8l71xT5A/mYIXxrtkguJ57W2NiTM GOE5rS0q6S2osM6ViwN5aEgr01bKmJw1GTK680rYWS9IHD4s2RxlAIwx1NiQ9oP9XXWR44 eCXG+rAabBNZ+ThW2JIreU/yTGzeD1g= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=2kZuikH82YSc7S3HfNANRsQo2YtDaV4SIY3/Jou1Rhs=; b=XgmiQpUPZkdrwGIkETA+Q6X97t mycvbbUMQMPAW6+yiqImO/SZLBqZHD33x2o/vxQafs/yKs2yNqB4XnKneI3cX4e9Bg/S+dhc2q53G PE5SwsGWZmTDUhL5Y1IffM6UwRRLIpcJ7xRxDYGw/n+L9yOYTX1L395fg2SqqvlqjogKGcO6SV28Z fMQrFmz27C5HoTPchxfMJ3pfrrwIa77t7E2NCHjn1QEcnJ2i4MPmGloIEJWOTQ4Mn5a0Hh9tqzp0R 5Cl1ngj3ZzgxDKHfbE5n9UyBMU1+qCDGDU3g1EkQ2LKlamb1OK+4QslmPGEERJztBFJL8ACj1pBuJ fIn0HkaA==; Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tmaSX-00000007diT-2H0i; Mon, 24 Feb 2025 15:33:29 +0000 Date: Mon, 24 Feb 2025 15:33:29 +0000 From: Matthew Wilcox To: Christoph Hellwig Cc: "Raphael S. Carvalho" , linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, djwong@kernel.org, Dave Chinner Subject: Re: [PATCH v2] mm: Fix error handling in __filemap_get_folio() with FGP_NOWAIT Message-ID: References: <20250224081328.18090-1-raphaelsc@scylladb.com> <20250224141744.GA1088@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250224141744.GA1088@lst.de> X-Rspam-User: X-Stat-Signature: x3wc1nxbzgmpj5f5jpsrkx9wtonw8g1f X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 8711A100020 X-HE-Tag: 1740411212-503378 X-HE-Meta: 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 3BI63i0D l8XVaveT6ZE+9rZiHNEm/VMyIdoi3z1XkG8Vkr64mRXz15cITVZvjAo/2Gt1+qTjhk2ZZs/5ojGsq+F7j07BydiSXIEbar5cH/PcrJno/4TUD7tbAcMrn3Bi5yYFQfedeNqCpWBdbI8+BjrTU6k98DOMtzEcvgIlOM7UdoHCT1OUbwtdaulzr7kkUf5iVV/sn807f7lIYw5A/DqeGBZwpj8IK/WPQBJRfQQCtB/IvGS/Fsn5jNIFPb6sZSwm3mAvzJDNe4FAVNgWCiROIdHZ0e8L7Wg== 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 Mon, Feb 24, 2025 at 03:17:44PM +0100, Christoph Hellwig wrote: > On Mon, Feb 24, 2025 at 05:13:28AM -0300, Raphael S. Carvalho wrote: > > + if (err) { > > + /* Prevents -ENOMEM from escaping to user space with FGP_NOWAIT */ > > + if ((fgp_flags & FGP_NOWAIT) && err == -ENOMEM) > > + err = -EAGAIN; > > return ERR_PTR(err); > > I don't think the comment is all that useful. It's also overly long. > > I'd suggest this instead: > > /* > * When NOWAIT I/O fails to allocate folios this could > * be due to a nonblocking memory allocation and not > * because the system actually is out of memory. > * Return -EAGAIN so that there caller retries in a > * blocking fashion instead of propagating -ENOMEM > * to the application. > */ I don't think it needs a comment at all, but the memory allocation might be for something other than folios, so your suggested comment is misleading.