linux-kernel - Re: [PATCH v1 6/7] virtio-mem: use page_offline

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: <20210503042220-mutt-send-email-mst@kernel.org>
Date:   Mon, 3 May 2021 04:23:47 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jason Wang <jasowang@...hat.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Mike Rapoport <rppt@...nel.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Oscar Salvador <osalvador@...e.de>,
        Michal Hocko <mhocko@...e.com>, Roman Gushchin <guro@...com>,
        Alex Shi <alex.shi@...ux.alibaba.com>,
        Steven Price <steven.price@....com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Aili Yao <yaoaili@...gsoft.com>, Jiri Bohac <jbohac@...e.cz>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        linux-hyperv@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v1 6/7] virtio-mem: use page_offline_(start|end) when
 setting PageOffline()

On Thu, Apr 29, 2021 at 02:25:18PM +0200, David Hildenbrand wrote:
> Let's properly use page_offline_(start|end) to synchronize setting
> PageOffline(), so we won't have valid page access to unplugged memory
> regions from /proc/kcore.
> 
> Signed-off-by: David Hildenbrand <david@...hat.com>


the patch looks good to me as such

Acked-by: Michael S. Tsirkin <mst@...hat.com>

Feel free to merge with rest of patcgset - it seems to mostly
live in the fs/mm space.

IF you respin, maybe add the explanation you sent in response to Mike's comments
in the commit log.


> ---
>  drivers/virtio/virtio_mem.c | 2 ++
>  mm/util.c                   | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
> index 10ec60d81e84..dc2a2e2b2ff8 100644
> --- a/drivers/virtio/virtio_mem.c
> +++ b/drivers/virtio/virtio_mem.c
> @@ -1065,6 +1065,7 @@ static int virtio_mem_memory_notifier_cb(struct notifier_block *nb,
>  static void virtio_mem_set_fake_offline(unsigned long pfn,
>  					unsigned long nr_pages, bool onlined)
>  {
> +	page_offline_begin();
>  	for (; nr_pages--; pfn++) {
>  		struct page *page = pfn_to_page(pfn);
>  
> @@ -1075,6 +1076,7 @@ static void virtio_mem_set_fake_offline(unsigned long pfn,
>  			ClearPageReserved(page);
>  		}
>  	}
> +	page_offline_end();
>  }
>  
>  /*
> diff --git a/mm/util.c b/mm/util.c
> index 95395d4e4209..d0e357bd65e6 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -1046,8 +1046,10 @@ void page_offline_begin(void)
>  {
>  	down_write(&page_offline_rwsem);
>  }
> +EXPORT_SYMBOL(page_offline_begin);
>  
>  void page_offline_end(void)
>  {
>  	up_write(&page_offline_rwsem);
>  }
> +EXPORT_SYMBOL(page_offline_end);
> -- 
> 2.30.2