Re: simultaneous creates in a directory

[Andrew Morton <akpm@digeo.com>]

William Lee Irwin III wrote:
> 
> > Even then, do we care?  Well hrm.  One page of ZONE_NORMAL per process
> > doesn't sound like the end of the world...
> 
> Well, it's one of the larger contributors to one of my OOM scenarios,

doom scenarios more like ;)

> which is why I asked willy to do it. Also consider /tmp/ ...
> 

Does Matthew's patch actually work?  Seems that we have to
perform lookups while holding that memory, and that requires
taking i_sem.

It's hard to get very excited about the seriousness of this
problem, I must say.

Any idea why the opens are taking so long?  Maybe someone is
throttled on writeback while holding i_sem?

It would be interesting to actually hunt down the current i_sem
holder and see what he's up to.  That's pretty easy:

struct task_struct *wli_task;

	down(&dir->i_sem);
	wli_task = current;

then go poke at wli_task in kgdb.