From 75558ad315488d40a18cb2c230ccacee24d20526 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Wed, 15 Mar 2023 14:31:24 +0300
Subject: [PATCH] sparc/mm: fix MAX_ORDER usage in tsb_grow()
Patch series "Fix confusion around MAX_ORDER".
MAX_ORDER currently defined as number of orders page allocator supports:
user can ask buddy allocator for page order between 0 and MAX_ORDER-1.
This definition is counter-intuitive and lead to number of bugs all over
the kernel.
Fix the bugs and then change the definition of MAX_ORDER to be
inclusive: the range of orders user can ask from buddy allocator is
0..MAX_ORDER now.
This patch (of 10):
MAX_ORDER is not inclusive: the maximum allocation order buddy allocator
can deliver is MAX_ORDER-1.
Fix MAX_ORDER usage in tsb_grow().
Link: https://lkml.kernel.org/r/20230315113133.11326-1-kirill.shutemov@linux.intel.com
Link: https://lkml.kernel.org/r/20230315113133.11326-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: David Miller <davem@davemloft.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
arch/sparc/mm/tsb.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index 9122057871610..dba8dffe21132 100644
--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -402,8 +402,8 @@ void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
unsigned long new_rss_limit;
gfp_t gfp_flags;
- if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
- max_tsb_size = (PAGE_SIZE << MAX_ORDER);
+ if (max_tsb_size > (PAGE_SIZE << (MAX_ORDER - 1)))
+ max_tsb_size = (PAGE_SIZE << (MAX_ORDER - 1));
new_cache_index = 0;
for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
--
2.30.2