Re: [PATCH 1/1] mm/vmalloc: remove preempt_disable/enable when do preloading

[Andrew Morton]

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 ;)