linux-kernel - Re: [PATCH 1/2] mm/readahead: stop readahead loop if memcg charge fails

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Thu, 1 Feb 2024 14:52:31 +0100
From: Jan Kara <jack@...e.cz>
To: Matthew Wilcox <willy@...radead.org>
Cc: Liu Shixin <liushixin2@...wei.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 1/2] mm/readahead: stop readahead loop if memcg charge
 fails

On Thu 01-02-24 13:47:03, Matthew Wilcox wrote:
> 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 ;-)

There's a read_pages() call just outside of the loop so this break is
actually fine AFAICT.

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR