Re: [PATCH 2/3] page allocator: Do not allow interrupts to use ALLOC_HARDER

David Rientjes
2009-11-02T20:53:56Z

On Mon, 2 Nov 2009, Christoph Lameter wrote:

> What is realtime in this scenario? There are no guarantees that reclaim
> wont have to occur. There are no guarantees anymore and therefore you
> cannot really call this realtime.
>

Realtime in this scenario is anything with a priority of MAX_RT_PRIO or
lower.

> Is realtime anything more than: "I want to have my patches merged"?
>

These allocations are not using ~__GFP_WAIT for a reason, they can block
on direct reclaim.

But we're convoluting this issue _way_ more than it needs to be. We have
used ALLOC_HARDER for these tasks as a convenience for over four years.
The fix here is to address an omittion in the page allocator refactoring
code that went into 2.6.31 that dropped the check for !in_interrupt().

If you'd like to raise the concern about the rt exemption being given
ALLOC_HARDER, then it is seperate from this fix.