On Fri, Oct 11, 2019 at 04:55:15PM -0700, Andrew Morton wrote:
> On Thu, 10 Oct 2019 17:17:49 +0200 Uladzislau Rezki <urezki@xxxxxxxxx> wrote:
>
> > > > : * The preload is done in non-atomic context, thus it allows us
> > > > : * to use more permissive allocation masks to be more stable under
> > > > : * low memory condition and high memory pressure.
> > > > : *
> > > > : * Even if it fails we do not really care about that. Just proceed
> > > > : * as it is. "overflow" path will refill the cache we allocate from.
> > > > : */
> > > > : if (!this_cpu_read(ne_fit_preload_node)) {
> > > >
> > > > Readability nit: local `pva' should be defined here, rather than having
> > > > function-wide scope.
> > > >
> > > > : pva = kmem_cache_alloc_node(vmap_area_cachep, GFP_KERNEL, node);
> > > >
> > > > Why doesn't this honour gfp_mask? If it's not a bug, please add
> > > > comment explaining this.
> > > >
> > But there is a comment, if understand you correctly:
> >
> > <snip>
> > * Even if it fails we do not really care about that. Just proceed
> > * as it is. "overflow" path will refill the cache we allocate from.
> > <snip>
>
> My point is that the alloc_vmap_area() caller passed us a gfp_t but
> this code ignores it, as does adjust_va_to_fit_type(). These *look*
> like potential bugs. If not, they should be commented so they don't
> look like bugs any more ;)
>
I got it, there was misunderstanding from my side :) I agree.
In the first case i should have used and respect the passed "gfp_mask",
like below:
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f48cd0711478..880b6e8cdeae 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1113,7 +1113,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
* Just proceed as it is. If needed "overflow" path
* will refill the cache we allocate from.
*/
- pva = kmem_cache_alloc_node(vmap_area_cachep, GFP_KERNEL, node);
+ pva = kmem_cache_alloc_node(vmap_area_cachep,
+ gfp_mask & GFP_RECLAIM_MASK, node);
spin_lock(&vmap_area_lock);
It should be sent as a separate patch, i think.
As for adjust_va_to_fit_type(), i can add a comment, since we can not
sleep there and the case is one per 1000000 or even lower with your proposal.
Does it sound good?
Thank you!
--
Vlad Rezki
