Re: sk_lock: inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage

[Wu Fengguang <fengguang.wu@intel.com>]

On Wed, Jul 15, 2009 at 12:04:32AM +0800, David Miller wrote:
> From: Herbert Xu <herbert@gondor.apana.org.au>
> Date: Fri, 10 Jul 2009 16:02:47 +0800
> 
> > On Fri, Jul 10, 2009 at 04:00:17PM +0800, Wu Fengguang wrote:
> >> 
> >> The (sk_allocation & ~__GFP_WAIT) cases should be rare, but I guess
> >> the networking code shall do it anyway, because sk_allocation defaults
> >> to GFP_KERNEL. It seems that currently the networking code simply uses
> >> a lot of GFP_ATOMIC, do they really mean "I cannot sleep"?
> > 
> > Yep because they're done from softirq context.
> 
> Yes, this is the core issue.

Yes, that's general true. But..

> All of Wu's talk about how "GFP_ATOMIC will wake up kswapd and
> therefore can succeed just as well as GFP_KERNEL" is not relevant,
> because GFP_ATOMIC means sleeping is not allowed.

We are talking about tcp_send_fin() here, which can sleep.

Thanks,
Fengguang