mm/damon/dbgfs: use '__GFP_NOWARN' for user-specified size buffer allocation

Patch series "DAMON fixes".

This patch (of 2):

DAMON users can trigger below warning in '__alloc_pages()' by invoking
write() to some DAMON debugfs files with arbitrarily high count
argument, because DAMON debugfs interface allocates some buffers based
on the user-specified 'count'.

if (unlikely(order >= MAX_ORDER)) {
WARN_ON_ONCE(!(gfp & __GFP_NOWARN));
return NULL;
}

Because the DAMON debugfs interface code checks failure of the
'kmalloc()', this commit simply suppresses the warnings by adding
'__GFP_NOWARN' flag.

Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface")
Signed-off-by: SeongJae Park <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

mm/damon/dbgfs.c

···
 	if (*ppos)
 		return ERR_PTR(-EINVAL);
 
-	kbuf = kmalloc(count + 1, GFP_KERNEL);
+	kbuf = kmalloc(count + 1, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return ERR_PTR(-ENOMEM);
 
···
 	char *kbuf;
 	ssize_t len;
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return -ENOMEM;
 
···
 	char *kbuf;
 	ssize_t len;
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return -ENOMEM;
 
···
 	char *kbuf;
 	ssize_t len;
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return -ENOMEM;