include/linux/page-flags-layout.h: correctly determine LAST_CPUPID_WIDTH

The naming convention used in include/linux/page-flags-layout.h:
  *_SHIFT: the number of bits trying to allocate
  *_WIDTH: the number of bits successfully allocated

So when it comes to LAST_CPUPID_WIDTH, we need to check whether all
previous *_WIDTH and LAST_CPUPID_SHIFT can fit into page flags. This
means we need to use NODES_WIDTH, not NODES_SHIFT.

Link: https://lkml.kernel.org/r/20210303071609.797782-1-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
index 7d4ec26..295c2c6 100644 (file)
--- a/include/linux/page-flags-layout.h
+++ b/include/linux/page-flags-layout.h
@@ -83,7 +83,7 @@
 #define KASAN_TAG_WIDTH 0
 #endif
 
-#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT+KASAN_TAG_WIDTH \
+#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_WIDTH+LAST_CPUPID_SHIFT+KASAN_TAG_WIDTH \
        <= BITS_PER_LONG - NR_PAGEFLAGS
 #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
 #else