[dm-devel] [PATCH] md/dm-ioctl.c: optimize memory allocation in copy_params

[Alasdair G Kergon]

On Tue, Jul 22, 2014 at 02:23:52AM +0100, Alasdair G Kergon wrote:
> Unanswered.  Let's ask the same question in a different way:
 
A quick search for 'vold' returns:
  https://android.googlesource.com/platform/system/vold/
and the code there requests a fixed 64K allocation to hold the names of
active volumes.

So unlike libdevmapper-based applications where a smaller allocation is
used at first and only extended if needed, Android just assumes that
64KB is enough for everyone.

So is your claim that:

1. This 64KB allocation for the brief duration of the ioctl to store the
names of active device-mapper volumes leads to memory problems?
[Mustn't the system *already* be in a bad state if this pushes it over
the limit?]

and

2. The systems on which this memory shortage occurs have so many volumes
(with long names?) that a smaller allocation would not suffice?

Alasdair