linux-kernel - Re: [PATCH v2 1/2] mm: Uncharge poisoned pages

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: <1493178300.4828.5.camel@gmail.com>
Date:   Wed, 26 Apr 2017 13:45:00 +1000
From:   Balbir Singh <bsingharora@...il.com>
To:     Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:     Laurent Dufour <ldufour@...ux.vnet.ibm.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH v2 1/2] mm: Uncharge poisoned pages

> > >  static int delete_from_lru_cache(struct page *p)
> > >  {
> > > +	if (memcg_kmem_enabled())
> > > +		memcg_kmem_uncharge(p, 0);
> > > +
> > 
> > The changelog is not quite clear, so we are uncharging a page using
> > memcg_kmem_uncharge for a page in swap cache/page cache?
> 
> Hi Balbir,
> 
> Yes, in the normal page lifecycle, uncharge is done in page free time.
> But in memory error handling case, in-use pages (i.e. swap cache and page
> cache) are removed from normal path and they don't pass page freeing code.
> So I think that this change is to keep the consistent charging for such a case.

I agree we should uncharge, but looking at the API name, it seems to
be for kmem pages, why are we not using mem_cgroup_uncharge()? Am I missing
something?

Balbir Singh.