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: <b0069788-2940-4634-ada1-224b927154dd@lucifer.local>
Date: Tue, 1 Jul 2025 09:37:13 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-doc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        virtualization@...ts.linux.dev, linux-fsdevel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jonathan Corbet <corbet@....net>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Jerrin Shaji George <jerrin.shaji-george@...adcom.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
        Eugenio Pérez <eperezma@...hat.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
        Zi Yan <ziy@...dia.com>, Matthew Brost <matthew.brost@...el.com>,
        Joshua Hahn <joshua.hahnjy@...il.com>, Rakie Kim <rakie.kim@...com>,
        Byungchul Park <byungchul@...com>, Gregory Price <gourry@...rry.net>,
        Ying Huang <ying.huang@...ux.alibaba.com>,
        Alistair Popple <apopple@...dia.com>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
        Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Minchan Kim <minchan@...nel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Brendan Jackman <jackmanb@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>, Jason Gunthorpe <jgg@...pe.ca>,
        John Hubbard <jhubbard@...dia.com>, Peter Xu <peterx@...hat.com>,
        Xu Xin <xu.xin16@....com.cn>,
        Chengming Zhou <chengming.zhou@...ux.dev>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Naoya Horiguchi <nao.horiguchi@...il.com>,
        Oscar Salvador <osalvador@...e.de>, Rik van Riel <riel@...riel.com>,
        Harry Yoo <harry.yoo@...cle.com>,
        Qi Zheng <zhengqi.arch@...edance.com>,
        Shakeel Butt <shakeel.butt@...ux.dev>
Subject: Re: [PATCH v1 04/29] mm/page_alloc: let page freeing clear any set
 page type

On Tue, Jul 01, 2025 at 10:34:33AM +0200, David Hildenbrand wrote:
> > > > > Reviewed-by: Zi Yan <ziy@...dia.com>
> > > > > Acked-by: Harry Yoo <harry.yoo@...cle.com>
> > > > > Signed-off-by: David Hildenbrand <david@...hat.com>

Based on discussion below, I'm good with this now with the comment change, so
feel free to add:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> > > > > ---
> > > > >    mm/page_alloc.c | 3 +++
> > > > >    1 file changed, 3 insertions(+)
> > > > >
> > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > > > > index 858bc17653af9..44e56d31cfeb1 100644
> > > > > --- a/mm/page_alloc.c
> > > > > +++ b/mm/page_alloc.c
> > > > > @@ -1380,6 +1380,9 @@ __always_inline bool free_pages_prepare(struct page *page,
> > > > >    			mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
> > > > >    		page->mapping = NULL;
> > > > >    	}
> > > > > +	if (unlikely(page_has_type(page)))
> > > > > +		page->page_type = UINT_MAX;
> > > >
> > > > Feels like this could do with a comment!
> > >
> > > /* Reset the page_type -> _mapcount to -1 */
> >
> > Hm this feels like saying 'the reason we set it to -1 is to set it to -1' :P
>
> Bingo! Guess why I didn't add a comment in the first place :P
>
> >
> > I'd be fine with something simple like
> >
> > /* Set page_type to reset value */
>
> "Reset the page_type (which overlays _mapcount)"
>
> ?

Sounds good thanks, have an R-b above on the basis of this change.

>
> > > But... Can't we just put a #define somewhere here to make life easy?
> Like:
>
> Given that Willy will change all that soon, I'm not in favor of doing that
> in this series.

Ah is he? I mean of course he is :))) this does seem like a prime target for the
ongoing memdesc/foliofication efforts.

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ