diff mbox series

[153/178] include/linux/page-flags-layout.h: correctly determine LAST_CPUPID_WIDTH

Message ID 20210430060104.JdsGwn9H0%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/178] arch/ia64/kernel/head.S: remove duplicate include | expand

Commit Message

Andrew Morton April 30, 2021, 6:01 a.m. UTC 
From: Yu Zhao <yuzhao@google.com>
Subject: 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>
---

 include/linux/page-flags-layout.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

--- a/include/linux/page-flags-layout.h~mm-correctly-determine-last_cpupid_width
+++ a/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