linux-kernel - Re: Warning from free_init

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Date:   Tue, 27 Sep 2016 11:36:40 -0700
From:   "H. Peter Anvin" <hpa@...or.com>
To:     Sitsofe Wheeler <sitsofe@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Richard W.M. Jones" <rjones@...hat.com>,
        Jeremy Katz <katzj@...hat.com>,
        "Brian C. Lane" <bcl@...hat.com>
Subject: Re: Warning from free_init_pages with large initrd

On September 27, 2016 3:20:06 AM PDT, Sitsofe Wheeler <sitsofe@...il.com> wrote:
>(See http://www.gossamer-threads.com/lists/linux/kernel/2534175 for
>the history of this thread )
>
>On 26 September 2016 at 20:00, Randy Dunlap <rdunlap@...radead.org>
>wrote:
>>
>> but the warning in free_init_pages() is about alignment, not size...
>> Maybe the concatenation is bad?
>
>What would l have to pull apart to be able to tell?
>
>Having said that I've just noticed that newer versions of the script
>concatenate an ISO to the initrd (rather than another cpio) -
>https://github.com/rhinstaller/livecd-tools/commit/8067be50907da9461e442c11a664c89e066ccac6#diff-88c69e43bb69726c532af3a136cc50e8
>. Unfortunately after rebuilding the initrd with the
>livecd-iso-to-pxeboot version from Fedora 24 the warning persists.
>CC'ing a few of the tool's authors on this email.

This really doesn't seem like a good approach, and certainly may cause memory exhaustion at boot time.  Still would be good to track down the problem.

Overall the idea of downloading the whole shebang in the initial TFTP transaction ID a really bad idea.  TFTP is slow and unreliable, and the PXE ROMs are often complete crap in terms of quality.  It would be way better to bring up a small initramfs and then fetch the rest using http or a similar protocol from the very high quality Linux TCP stack.  As far as I know, Fedora has supported this mode for *ages*.
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