selftests/vm/transhuge-stress: fix ram size thinko

When executing transhuge-stress with an argument to specify the virtual
memory size for testing, the ram size is reported as 0, e.g.

transhuge-stress 384
thp-mmap: allocate 192 transhuge pages, using 384 MiB virtual memory and 0 MiB of ram
thp-mmap: 0.184 s/loop, 0.957 ms/page, 2090.265 MiB/s 192 succeed, 0 failed

This appears to be due to a thinko in commit 0085d61fe05e
("selftests/vm/transhuge-stress: stress test for memory compaction"),
where, at a guess, the intent was to base "xyz MiB of ram" on `ram`
size.

Here are results after using `ram` size:

thp-mmap: allocate 192 transhuge pages, using 384 MiB virtual memory and 14 MiB of ram

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: 0085d61fe05e ("selftests/vm/transhuge-stress: stress test for memory compaction")
Signed-off-by: George G. Davis <[e-mail]>
Cc: Konstantin Khlebnikov <[e-mail]>
Cc: Eugeniu Rosca <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

tools/testing/selftests/vm/transhuge-stress.c

···
 
 	warnx("allocate %zd transhuge pages, using %zd MiB virtual memory"
 	      " and %zd MiB of ram", len >> HPAGE_SHIFT, len >> 20,
-	      len >> (20 + HPAGE_SHIFT - PAGE_SHIFT - 1));
+	      ram >> (20 + HPAGE_SHIFT - PAGE_SHIFT - 1));
 
 	pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
 	if (pagemap_fd < 0)