UPSTREAM: mm, slab: shorten kmalloc cache names for large sizes

Kmalloc cache names can get quite long for large object sizes, when the
sizes are expressed in bytes.  Use 'k' and 'M' prefixes to make the names
as short as possible e.g.  in /proc/slabinfo.  This works, as we mostly
use power-of-two sizes, with exceptions only below 1k.

Example: 'kmalloc-4194304' becomes 'kmalloc-4M'

Link: http://lkml.kernel.org/r/20180731090649.16028-7-vbabka@suse.cz
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

(cherry picked from commit f0d77874143df90f9831f30254eb149fc4d76b40)

Bug: 138148041
Test: verify KReclaimable accounting after ION allocation+deallocation
Change-Id: Ib7facb09f333ccd7c224a08e59dede9e6a0c1e0c
Signed-off-by: Suren Baghdasaryan <surenb@google.com>

mm/slab_common.c

@@ -994,15 +994,15 @@ const struct kmalloc_info_struct kmalloc_info[] __initconst = {
 	{"kmalloc-16",             16},		{"kmalloc-32",             32},
 	{"kmalloc-64",             64},		{"kmalloc-128",           128},
 	{"kmalloc-256",           256},		{"kmalloc-512",           512},
-	{"kmalloc-1024",         1024},		{"kmalloc-2048",         2048},
-	{"kmalloc-4096",         4096},		{"kmalloc-8192",         8192},
-	{"kmalloc-16384",       16384},		{"kmalloc-32768",       32768},
-	{"kmalloc-65536",       65536},		{"kmalloc-131072",     131072},
-	{"kmalloc-262144",     262144},		{"kmalloc-524288",     524288},
-	{"kmalloc-1048576",   1048576},		{"kmalloc-2097152",   2097152},
-	{"kmalloc-4194304",   4194304},		{"kmalloc-8388608",   8388608},
-	{"kmalloc-16777216", 16777216},		{"kmalloc-33554432", 33554432},
-	{"kmalloc-67108864", 67108864}
+	{"kmalloc-1k",           1024},		{"kmalloc-2k",           2048},
+	{"kmalloc-4k",           4096},		{"kmalloc-8k",           8192},
+	{"kmalloc-16k",         16384},		{"kmalloc-32k",         32768},
+	{"kmalloc-64k",         65536},		{"kmalloc-128k",       131072},
+	{"kmalloc-256k",       262144},		{"kmalloc-512k",       524288},
+	{"kmalloc-1M",        1048576},		{"kmalloc-2M",        2097152},
+	{"kmalloc-4M",        4194304},		{"kmalloc-8M",        8388608},
+	{"kmalloc-16M",      16777216},		{"kmalloc-32M",      33554432},
+	{"kmalloc-64M",      67108864}
 };
 
 /*
@@ -1052,6 +1052,21 @@ void __init setup_kmalloc_cache_index_table(void)
 	}
 }
 
+static const char *
+kmalloc_cache_name(const char *prefix, unsigned int size)
+{
+
+	static const char units[3] = "\0kM";
+	int idx = 0;
+
+	while (size >= 1024 && (size % 1024 == 0)) {
+		size /= 1024;
+		idx++;
+	}
+
+	return kasprintf(GFP_NOWAIT, "%s-%u%c", prefix, size, units[idx]);
+}
+
 static void __init
 new_kmalloc_cache(int idx, int type, unsigned long flags)
 {
@@ -1059,7 +1074,7 @@ new_kmalloc_cache(int idx, int type, unsigned long flags)
 
 	if (type == KMALLOC_RECLAIM) {
 		flags |= SLAB_RECLAIM_ACCOUNT;
-		name = kasprintf(GFP_NOWAIT, "kmalloc-rcl-%lu",
+		name = kmalloc_cache_name("kmalloc-rcl",
 						kmalloc_info[idx].size);
 		BUG_ON(!name);
 	} else {
@@ -1107,8 +1122,7 @@ void __init create_kmalloc_caches(unsigned long flags)
 
 		if (s) {
 			int size = kmalloc_size(i);
-			char *n = kasprintf(GFP_NOWAIT,
-				 "dma-kmalloc-%d", size);
+			const char *n = kmalloc_cache_name("dma-kmalloc", size);
 
 			BUG_ON(!n);
 			kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache(