Re: udevadm settle persistently failing

[DJ Lucas <dj@lucasit.com>]

On 05/15/2011 01:32 PM, Tom Gundersen wrote:
> On Sun, May 15, 2011 at 8:19 PM, Nix<nix@esperi.org.uk>  wrote:
>> I know that you're not supposed to rely on 'udevadm settle' anymore, but
>> I rely on it across the board for systems with root filesystems that
>> aren't expected to move around (i.e. all of them), because massively
>> reengineering working systems' boot processes is generally considered a
>> bad thing. And it's stopped working. Given how many things expect /dev
>> to be populated, this has fairly serious effects.
>>
>> I can be certain that as of somewhere between udev 164 and 167, 'udevadm
>> settle' has stopped waiting for block devices to appear (though I
>> suspect others have vanished too). I'm booting udev as recommended in
>> the release notes, via
>>
>>   udevd --daemon
>>   udevadm trigger --action­d --type=subsystems
>>   udevadm trigger --action­d --typeÞvices
>>   udevadm settle
>
> We are doing the same on Arch and today I started seeing bug reports
> (after the upgrade to udev 168). So here are my two cents:
>
> Most of the time the problem seems to be related to LVM, but I have
> also seen regular block devices having problems. As would be expected
> using devtmpfs greatly reduces (if not eliminates) the problem. My
> guess was (like Nix said) that "udevadm settle" is somehow broken.
>
> Some related bug reports:
>
> Arch:<https://bugs.archlinux.org/task/24288>,
> Debian:<http://bugs.debian.org/cgi-bin/bugreport.cgi?bugb4010>.
>
> Cheers,
>
> Tom
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Just to add a "me too" regarding regular block devices. First noticed 
with 168, coming from 165. /dev was tmpfs and swap is /dev/sda3 and 
mounted immediately after udevadm --settle. Kernel is 2.6.36.2. In 
addition to the udev change, I added the /run mount point to the mix 
(started very early, directly in rc before any scripts are run). Moving 
to devtmpfs 'fixed' it for me, but that was because devtmpfs has the raw 
sd* nodes, as explained to me by another dev. If I flip to use by-id, it 
breaks again. I plan to go back and see exactly where stuff broke, but 
haven't had the time just yet, more pressing issues. Probably a 
Wednesday evening project (CDT).

-- DJ Lucas


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