Re: [RFC] 4KB stack + irq stack for x86

[Stephen Lord <lord@sgi.com>]

On Wed, 2002-06-05 at 20:42, Benjamin LaHaise wrote:
> On Thu, Jun 06, 2002 at 03:15:17AM +0200, Andi Kleen wrote:
> > The scenario Steve outlined was rather optimistic - more pessimistic
> > case would be e.g:
> > you run NBD which calls the network stack with an complex file system on top
> > of it called by something else complex that does a GFP_KERNEL alloc and VM 
> > wants to flush a page via the NBD file system - I don't see how you'll ever 
> > manage to fit that into 4K.
> 
> Which is, honestly, a bug.  The IO subsystem should not be capable of 
> engaging in such deep recursion.  ext2/ext3 barely allocate anything 
> on the stack (0x90 bytes at most in only a couple of calls), the vm 
> is in a similar state, and even the network stack's largest allocations 
> are in syscalls and timer code.  Face it, the majority of code that is 
> or could cause problems are things that probably need fixing anyways.
> 

Well, reclaiming memory within the same thread which is allocating
memory is surely the root cause of this, not the I/O system.


Steve