On Tue, 20 Jul 2010, David Miller wrote:
> > The kmalloc() in mdesc_kmalloc() is failable, so remove __GFP_NOFAIL from
> > its mask.
> >
> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
>
> The __GFP_NOFAIL is there intentionally.
>
> The code above this, in the cases where the machine description is
> dynamically updated by the hypervisor at run time, long after boot,
> has no failure handling.
>
> We absolutely must accept the machine descriptor update and fetch it
> from the hypervisor into a new buffer.
>
> Please don't remove this.
>
Ok, fair enough. I was convinced by the error handling in both
mdesc_update() and mdesc_kmallloc() that this was a failable allocation,
but I understand how mdesc_update() must succeed given your description.
We can remove those branches from those two functions, though, since
__GFP_NOFAIL will always succeed before returning.
I'm planning on replacing __GFP_NOFAIL with a __GFP_KILLABLE flag that
will use all of the page allocator's capabilities (direct reclaim, memory
compaction for order > 0, and the oom killer) before failing. Then,
existing __GFP_NOFAIL users can use
do {
page = alloc_page(GFP_KERNEL | __GFP_KILLABLE);
} while (!page);
to remove several branches from the page allocator that we'll no longer
need. I'll do this in phase two and make sure to convert this instance to
do that.
Thanks!
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>