linux-kernel - Re: [PATCH net-next v7 1/5] mm: add a signature in struct page

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:   Mon, 7 Jun 2021 15:58:23 +0200
From:   Matteo Croce <mcroce@...ux.microsoft.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     netdev@...r.kernel.org, linux-mm@...ck.org,
        Ayush Sawal <ayush.sawal@...lsio.com>,
        Vinay Kumar Yadav <vinay.yadav@...lsio.com>,
        Rohit Maheshwari <rohitm@...lsio.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Russell King <linux@...linux.org.uk>,
        Mirko Lindner <mlindner@...vell.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Tariq Toukan <tariqt@...dia.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        Boris Pismenny <borisp@...dia.com>,
        Arnd Bergmann <arnd@...db.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>, Yu Zhao <yuzhao@...gle.com>,
        Will Deacon <will@...nel.org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Roman Gushchin <guro@...com>, Hugh Dickins <hughd@...gle.com>,
        Peter Xu <peterx@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Alexander Lobakin <alobakin@...me>,
        Cong Wang <cong.wang@...edance.com>, wenxu <wenxu@...oud.cn>,
        Kevin Hao <haokexin@...il.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Marco Elver <elver@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Yunsheng Lin <linyunsheng@...wei.com>,
        Guillaume Nault <gnault@...hat.com>,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
        bpf@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        David Ahern <dsahern@...il.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Saeed Mahameed <saeedm@...dia.com>,
        Andrew Lunn <andrew@...n.ch>, Paolo Abeni <pabeni@...hat.com>,
        Sven Auhagen <sven.auhagen@...eatech.de>
Subject: Re: [PATCH net-next v7 1/5] mm: add a signature in struct page

On Mon, Jun 7, 2021 at 3:53 PM Matthew Wilcox <willy@...radead.org> wrote:
>
> On Sun, Jun 06, 2021 at 03:50:54AM +0200, Matteo Croce wrote:
> > And change all the *_pfmemalloc functions to use page->lru.next like this?
> >
> > @@ -1668,10 +1668,12 @@ struct address_space *page_mapping(struct page *page);
> > static inline bool page_is_pfmemalloc(const struct page *page)
> > {
> >        /*
> > -        * Page index cannot be this large so this must be
> > -        * a pfmemalloc page.
> > +        * This is not a tail page; compound_head of a head page is unused
> > +        * at return from the page allocator, and will be overwritten
> > +        * by callers who do not care whether the page came from the
> > +        * reserves.
> >         */
>
> The comment doesn't make a lot of sense if we're switching to use
> lru.next.  How about:
>
>         /*
>          * lru.next has bit 1 set if the page is allocated from the
>          * pfmemalloc reserves.  Callers may simply overwrite it if
>          * they do not need to preserve that information.
>          */

Sounds good!

-- 
per aspera ad upstream