linux-kernel - Re: [PATCH RFC 5/9] x86, mm: Use cache of page tables

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: <588d4b82a6cb47383e73e5d375b2b1766b4d3511.camel@intel.com>
Date:   Fri, 7 May 2021 16:27:27 +0000
From:   "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To:     "shakeelb@...gle.com" <shakeelb@...gle.com>
CC:     "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        "luto@...nel.org" <luto@...nel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rppt@...nel.org" <rppt@...nel.org>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
        "Weiny, Ira" <ira.weiny@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH RFC 5/9] x86, mm: Use cache of page tables

On Thu, 2021-05-06 at 11:24 -0700, Shakeel Butt wrote:
> On Tue, May 4, 2021 at 5:36 PM Rick Edgecombe
> <rick.p.edgecombe@...el.com> wrote:
> > 
> [...]
> > +#ifdef CONFIG_PKS_PG_TABLES
> > +struct page *alloc_table(gfp_t gfp)
> > +{
> > +       struct page *table;
> > +
> > +       if (!pks_page_en)
> > +               return alloc_page(gfp);
> > +
> > +       table = get_grouped_page(numa_node_id(), &gpc_pks);
> > +       if (!table)
> > +               return NULL;
> > +
> > +       if (gfp & __GFP_ZERO)
> > +               memset(page_address(table), 0, PAGE_SIZE);
> > +
> > +       if (memcg_kmem_enabled() &&
> > +           gfp & __GFP_ACCOUNT &&
> > +           !__memcg_kmem_charge_page(table, gfp, 0)) {
> > +               free_table(table);
> > +               table = NULL;
> > +       }
> > +
> > +       VM_BUG_ON_PAGE(*(unsigned long *)&table->ptl, table);
> 
> table can be NULL due to charge failure.

Argh, yes. Thank you. I'll remove the VM_BUG_ON, it was left
accidentally.