+ mm-page_alloc-remove-unnecessary-check-in-break_down_buddy_pages.patch added to mm-unstable branch

+ mm-page_alloc-remove-unnecessary-check-in-break_down_buddy_pages.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/page_alloc: remove unnecessary check in break_down_buddy_pages
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_alloc-remove-unnecessary-check-in-break_down_buddy_pages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-remove-unnecessary-check-in-break_down_buddy_pages.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Kemeng Shi <shikemeng@huaweicloud.com>
Subject: mm/page_alloc: remove unnecessary check in break_down_buddy_pages
Date: Wed, 27 Sep 2023 18:35:13 +0800

Patch series "Two minor cleanups to break_down_buddy_pages", v2.

Two minor cleanups to break_down_buddy_pages.


This patch (of 2):

1. We always have target in range started with next_page and full free
   range started with current_buddy.

2. The last split range size is 1 << low and low should be >= 0, then
   size >= 1.  So page + size != page is always true (because size > 0). 
   As summary, current_page will not equal to target page.

Link: https://lkml.kernel.org/r/20230927103514.98281-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20230927103514.98281-2-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_alloc.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/mm/page_alloc.c~mm-page_alloc-remove-unnecessary-check-in-break_down_buddy_pages
+++ a/mm/page_alloc.c
@@ -6696,10 +6696,8 @@ static void break_down_buddy_pages(struc
 		if (set_page_guard(zone, current_buddy, high, migratetype))
 			continue;
 
-		if (current_buddy != target) {
-			add_to_free_list(current_buddy, zone, high, migratetype);
-			set_buddy_order(current_buddy, high);
-		}
+		add_to_free_list(current_buddy, zone, high, migratetype);
+		set_buddy_order(current_buddy, high);
 	}
 }
 
_

Patches currently in -mm which might be from shikemeng@huaweicloud.com are

mm-page_alloc-correct-start-page-when-guard-page-debug-is-enabled.patch
mm-compaction-use-correct-list-in-move_freelist_head-tail.patch
mm-compaction-call-list_is_first-last-more-intuitively-in-move_freelist_head-tail.patch
mm-compaction-correctly-return-failure-with-bogus-compound_order-in-strict-mode.patch
mm-compaction-remove-repeat-compact_blockskip_flush-check-in-reset_isolation_suitable.patch
mm-compaction-improve-comment-of-is_via_compact_memory.patch
mm-compaction-factor-out-code-to-test-if-we-should-run-compaction-for-target-order.patch
mm-page_alloc-remove-unnecessary-check-in-break_down_buddy_pages.patch
mm-page_alloc-remove-unnecessary-next_page-in-break_down_buddy_pages.patch