Re: [lc-devel] Lockups in 2.4.17

[Livio B. S. <li...@li...>]

Howdy David!

David Chow writes:
> Dear all,
> 
> I have a couple of lockups in 2.4.17 with compressed cache. Not sure its
> linux related or compressed cache related.
> 
> I happens in 2 situations,
> 1. The beginning to swap out pages, when the memory getting low and the
> kernel beginging to swap out pages, this only happened once, not often
> triggered.

  Humm, this one, I have no idea what is happening.

> 2. Swap is gradually increasing, when its full, the machine lockup. I
> think this is not out of memory, infact kernel should free up some
> unused pages or reclaim some swaps. It seems the swap usage never
> decrease, and it seems the kernel have problem freeing up swap spaces.

  Yes, I've seen this one. This is a bug with the vswap (Virtual Swap)
mechanism. I talked to Rodrigo about it, and he thinks that the variable
'estimated_free_space' (in mm/comp_cache/vswap.c), is being wrongly calculated,
and hinting to the cache that there is still some space left, and giving out
addresses, which in reality wouln't fit into memory.... then when that address
is requested things just explode.

  We are trying to look for a good way to fix it. Maybe, if you have time, you
can take a look at it.

  best regards,

--  
  Livio <li...@li...>