Re: Linux 2.4.0-test8 and swap/journaling fs on raid

From: Neil Brown (neilb@cse.unsw.edu.au)
Date: Fri Sep 29 2000 - 17:29:50 EST


On Friday September 29, riel@conectiva.com.br wrote:
> On Fri, 29 Sep 2000, Pavel Machek wrote:
>
> > Are you sure there are no deadlock-when-low-on-memory bugs
> > hiding somewhere? swap over nbd also *seems* to work.

Raid preallocates all the memory that it needs.
When raid1 runs out of pre-allocated memory, it will try to see if
kmalloc(GFP_BUFFER) has any to spare and will use it transiently, but
it copes quite well if kmalloc doesn't provide any.
I think this is adequate to fend of deadlock-when-low-on-memory
problems.

But surely, deadlock-when-low-on-memory problems will hurt normal
filesystem activity just as much as swap activity -- is that right?

>
> Good that you mention this. I should look into this some
> day, preferably in the very near future.
>
> (added to my VM TODO list)

Always happy to have others do code reviews!

NeilBrown
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