[Pkg-sysvinit-devel] Bug#738855: initscripts: Skip killing process starting with @

Helmut Grohne helmut at subdivi.de
Thu Feb 13 15:05:23 UTC 2014

Hi Dimitri,

On Thu, Feb 13, 2014 at 01:58:23PM +0000, Dmitrijs Ledkovs wrote:
> There is convention starting that processes whos name starts with '@'
> shouldn't be killed. It is used to indicate that process is needed to
> manage root device / cleanly unmount the root filesystem.
> At least mdadm supports it for it's 'mdmon' process which is daemon
> needed to manage containers (aka fakeraid controllers - Intel Matrix
> Raid and DDF).
> I've implemented a patch using pgrep, thus it's optional code in
> sendsigs if pgrep is not available.

Are you sure that the described behaviour is desirable at all?

I argue that evading sendsigs should be a privileged operation. If it
isn't, I can simply rename my process to start with an '@' and block
umounting filesystems possibly causing data loss (due to failing
umount). I am not sure that the drafted scenario can actually happen in
practise, but from a first glance it seems to be the case. Thus applying
your patch would open up the possibility for data loss.

Do you concur with this reasoning?

 Yes -> Please close this bug.
 No -> Please explain in what way my argument is flawed.

Maybe mdmon should use the existing mechanism and write its PID to
/run/sendsigs.omit.d/mdmon instead?



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