mm/vmalloc: respect passed gfp_mask when doing preloading

Allocation functions should comply with the given gfp_mask as much as
possible. The preallocation code in alloc_vmap_area doesn't follow that
pattern and it is using a hardcoded GFP_KERNEL. Although this doesn't
really make much difference because vmalloc is not GFP_NOWAIT compliant
in general (e.g. page table allocations are GFP_KERNEL) there is no
reason to spread that bad habit and it is good to fix the antipattern.

[[e-mail]: rewrite changelog]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Uladzislau Rezki (Sony) <[e-mail]>
Acked-by: Michal Hocko <[e-mail]>
Cc: Daniel Wagner <[e-mail]>
Cc: Hillf Danton <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Oleksiy Avramchenko <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Sebastian Andrzej Siewior <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

mm/vmalloc.c

···
 		return ERR_PTR(-EBUSY);
 
 	might_sleep();
+	gfp_mask = gfp_mask & GFP_RECLAIM_MASK;
 
-	va = kmem_cache_alloc_node(vmap_area_cachep,
-			gfp_mask & GFP_RECLAIM_MASK, node);
+	va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
 	if (unlikely(!va))
 		return ERR_PTR(-ENOMEM);
 
···
 	 * Only scan the relevant parts containing pointers to other objects
 	 * to avoid false negatives.
 	 */
-	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask & GFP_RECLAIM_MASK);
+	kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask);
 
 retry:
 	/*
···
 		 * 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, node);
 
 	spin_lock(&vmap_area_lock);