linux-kernel - Re: [PATCH v4 4/4] mm: convert page kmemcg type to a page memcg flag

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]

Message-ID: <20201001183013.GB2706729@carbon.DHCP.thefacebook.com>
Date:   Thu, 1 Oct 2020 11:30:13 -0700
From:   Roman Gushchin <guro@...com>
To:     Michal Koutný <mkoutny@...e.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <kernel-team@...com>
Subject: Re: [PATCH v4 4/4] mm: convert page kmemcg type to a page memcg flag

On Thu, Oct 01, 2020 at 07:00:36PM +0200, Michal Koutny wrote:
> Hi.
> 
> On Wed, Sep 30, 2020 at 05:27:10PM -0700, Roman Gushchin <guro@...com> wrote:
> > @@ -369,8 +371,12 @@ enum page_memcg_data_flags {
> >   */
> >  static inline struct mem_cgroup *page_memcg(struct page *page)
> >  {
> > +	unsigned long memcg_data = page->memcg_data;
> > +
> >  	VM_BUG_ON_PAGE(PageSlab(page), page);
> > -	return (struct mem_cgroup *)page->memcg_data;
> > +	VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page);
> > +
> > +	return (struct mem_cgroup *)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
> >  }
> Shouldn't this change go also into page_memcg_rcu()? (I don't think the
> current single user (workingset_activation() would pass a non-slab
> kernel page but for consistency sake.)

Yes, a good idea, I will add it.

Thanks!