linux-kernel - Re: [PATCH v3] xen/balloon: add late_initcall

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <11956c14-f1f7-70f0-40a6-aad31a264af6@oracle.com>
Date:   Fri, 29 Oct 2021 17:46:18 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org
Cc:     Stefano Stabellini <sstabellini@...nel.org>,
        stable@...r.kernel.org,
        Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>
Subject: Re: [PATCH v3] xen/balloon: add late_initcall_sync() for initial
 ballooning done


On 10/29/21 10:20 AM, Juergen Gross wrote:
> --- a/Documentation/ABI/stable/sysfs-devices-system-xen_memory
> +++ b/Documentation/ABI/stable/sysfs-devices-system-xen_memory
> @@ -84,3 +84,13 @@ Description:
>   		Control scrubbing pages before returning them to Xen for others domains
>   		use. Can be set with xen_scrub_pages cmdline
>   		parameter. Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT.
> +
> +What:		/sys/devices/system/xen_memory/xen_memory0/boot_timeout
> +Date:		November 2021
> +KernelVersion:	5.16
> +Contact:	xen-devel@...ts.xenproject.org
> +Description:
> +		The time (in seconds) to wait before giving up to boot in case
> +		initial ballooning fails to free enough memory. Applies only
> +		when running as HVM or PVH guest and started with less memory
> +		configured than allowed at max.


How is this going to be used? We only need this during boot.


>   
> -		state = update_schedule(state);
> +		balloon_state = update_schedule(balloon_state);


Now that balloon_state has whole file scope it can probably be updated inside update_schedule().


> +	while ((credit = current_credit()) < 0) {
> +		if (credit != last_credit) {
> +			last_changed = jiffies;
> +			last_credit = credit;
> +		}
> +		if (balloon_state == BP_ECANCELED) {


What about other states? We are really waiting for BP_DONE, aren't we?


-boris


> +			pr_warn_once("Initial ballooning failed, %ld pages need to be freed.\n",
> +				     -credit);
> +			if (jiffies - last_changed >=
> +			    HZ * balloon_stats.boot_timeout)
> +				panic("Initial ballooning failed!\n");
> +		}
> +