linux-kernel - Re: [PATCH v1 6/8] vmw_balloon: mark inflated pages PG

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Date:   Wed, 21 Nov 2018 03:22:26 +0000
From:   Nadav Amit <namit@...are.com>
To:     David Hildenbrand <david@...hat.com>
CC:     linux-mm <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        xen-devel <xen-devel@...ts.xenproject.org>,
        kexec-ml <kexec@...ts.infradead.org>,
        pv-drivers <pv-drivers@...are.com>,
        Xavier Deguillard <xdeguillard@...are.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Julien Freche <jfreche@...are.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        "Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH v1 6/8] vmw_balloon: mark inflated pages PG_offline

Thanks for this patch!

> On Nov 19, 2018, at 2:16 AM, David Hildenbrand <david@...hat.com> wrote:
> 
> Mark inflated and never onlined pages PG_offline, to tell the world that
> the content is stale and should not be dumped.
> 
> Cc: Xavier Deguillard <xdeguillard@...are.com>
> Cc: Nadav Amit <namit@...are.com>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Julien Freche <jfreche@...are.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: "Michael S. Tsirkin" <mst@...hat.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
> drivers/misc/vmw_balloon.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
> index e6126a4b95d3..8cc8bd9a4e32 100644
> --- a/drivers/misc/vmw_balloon.c
> +++ b/drivers/misc/vmw_balloon.c
> @@ -544,6 +544,36 @@ unsigned int vmballoon_page_order(enum vmballoon_page_size_type page_size)
> 	return page_size == VMW_BALLOON_2M_PAGE ? VMW_BALLOON_2M_ORDER : 0;
> }
> 
> +/**
> + * vmballoon_mark_page_offline() - mark a page as offline
> + * @page: pointer for the page

If possible, please add a period at the end of the sentence (yes, I know I
got it wrong in some places too).

> + * @page_size: the size of the page.
> + */
> +static void
> +vmballoon_mark_page_offline(struct page *page,
> +			    enum vmballoon_page_size_type page_size)
> +{
> +	int i;
> +
> +	for (i = 0; i < 1ULL << vmballoon_page_order(page_size); i++)

Can you please do instead:

	unsigned int;

	for (i = 0; i < vmballoon_page_in_frames(page_size); i++)


> +		__SetPageOffline(page + i);
> +}
> +
> +/**
> + * vmballoon_mark_page_online() - mark a page as online
> + * @page: pointer for the page
> + * @page_size: the size of the page.
> + */
> +static void
> +vmballoon_mark_page_online(struct page *page,
> +			   enum vmballoon_page_size_type page_size)
> +{
> +	int i;
> +
> +	for (i = 0; i < 1ULL << vmballoon_page_order(page_size); i++)
> +		__ClearPageOffline(page + i);

Same here (use vmballoon_page_in_frames).

> +}
> +
> /**
>  * vmballoon_page_in_frames() - returns the number of frames in a page.
>  * @page_size: the size of the page.
> @@ -612,6 +642,7 @@ static int vmballoon_alloc_page_list(struct vmballoon *b,
> 					 ctl->page_size);
> 
> 		if (page) {
> +			vmballoon_mark_page_offline(page, ctl->page_size);
> 			/* Success. Add the page to the list and continue. */
> 			list_add(&page->lru, &ctl->pages);
> 			continue;
> @@ -850,6 +881,7 @@ static void vmballoon_release_page_list(struct list_head *page_list,
> 
> 	list_for_each_entry_safe(page, tmp, page_list, lru) {
> 		list_del(&page->lru);
> +		vmballoon_mark_page_online(page, page_size);
> 		__free_pages(page, vmballoon_page_order(page_size));
> 	}

We would like to test it in the next few days, but in the meanwhile, after
you address these minor issues:

Acked-by: Nadav Amit <namit@...are.com>

Thanks again,
Nadav