Received-SPF: pass (google.com: domain of linux-kernel+bounces-48260-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Thu, 1 Feb 2024 13:47:03 +0000
From: Matthew Wilcox <willy@infradead.org>
To: Liu Shixin <liushixin2@huawei.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH 1/2] mm/readahead: stop readahead loop if memcg charge
 fails
Message-ID: <Zbug14NoOHFmfLst@casper.infradead.org>
References: <20240201100835.1626685-1-liushixin2@huawei.com>
 <20240201100835.1626685-2-liushixin2@huawei.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240201100835.1626685-2-liushixin2@huawei.com>

On Thu, Feb 01, 2024 at 06:08:34PM +0800, Liu Shixin wrote:
> @@ -247,9 +248,12 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
>  		folio = filemap_alloc_folio(gfp_mask, 0);
>  		if (!folio)
>  			break;
> -		if (filemap_add_folio(mapping, folio, index + i,
> -					gfp_mask) < 0) {
> +
> +		ret = filemap_add_folio(mapping, folio, index + i, gfp_mask);
> +		if (ret < 0) {
>  			folio_put(folio);
> +			if (ret == -ENOMEM)
> +				break;

No, that's too early.  You've still got a batch of pages which were
successfully added; you have to read them.  You were only off by one
line though ;-)

>  			read_pages(ractl);
>  			ractl->_index++;
>  			i = ractl->_index + ractl->_nr_pages - index - 1;
> -- 
> 2.25.1
> 
>