mm: remove obsoleted alloc_pages cpuset comment

When a cpuset's nodemask is updated, all attached tasks have their cached
task->mems_allowed updated by a heap instead of requiring an explicit call
to cpuset_update_task_memory_state(), which has since been removed in
58568d2a ("cpuset,mm: update tasks'
mems_allowed in time").

Remove the obsoleted comment from the page allocator.

Cc: Paul Menage <menage@google.com>
Acked-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -1627,10 +1627,6 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
 
 	/* We now go into synchronous reclaim */
 	cpuset_memory_pressure_bump();
-
-	/*
-	 * The task's cpuset might have expanded its set of allowable nodes
-	 */
 	p->flags |= PF_MEMALLOC;
 	lockdep_set_current_reclaim_state(gfp_mask);
 	reclaim_state.reclaimed_slab = 0;