ref_tracker: remove redundant __GFP_NOWARN

Commit 16f5dfbc851b ("gfp: include __GFP_NOWARN in GFP_NOWAIT") made
GFP_NOWAIT implicitly include __GFP_NOWARN.

Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT (e.g.,
`GFP_NOWAIT | __GFP_NOWARN`) is now redundant. Let's clean up these
redundant flags across subsystems.

No functional changes.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Qianfeng Rong <[e-mail]>
Cc: Matthew Wilcox (Oracle) <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

lib/ref_tracker.c

···
 	struct ref_tracker *tracker;
 
 	stats = kmalloc(struct_size(stats, stacks, limit),
-			GFP_NOWAIT | __GFP_NOWARN);
+			GFP_NOWAIT);
 	if (!stats)
 		return ERR_PTR(-ENOMEM);
 	stats->total = 0;
···
 		return;
 	}
 
-	sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);
+	sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT);
 
 	for (i = 0, skipped = stats->total; i < stats->count; ++i) {
 		stack = stats->stacks[i].stack_handle;
···
 	}
 	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
 	stack_handle = stack_depot_save(entries, nr_entries,
-					GFP_NOWAIT | __GFP_NOWARN);
+					GFP_NOWAIT);
 
 	spin_lock_irqsave(&dir->lock, flags);
 	if (tracker->dead) {