[020/227] mm/writeback: minor clean up for highmem_dirtyable_memory

Commit Message

Andrew Morton March 22, 2022, 9:39 p.m. UTC

From: Miaohe Lin <[e-mail]>
Subject: mm/writeback: minor clean up for highmem_dirtyable_memory

Since commit a804552b9a15 ("mm/page-writeback.c: fix dirty_balance_reserve
subtraction from dirtyable memory"), local variable x can not be negative.
And it can not overflow when it is the total number of dirtyable highmem
pages.  Thus remove the unneeded comment and overflow check.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Miaohe Lin <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/page-writeback.c |   12 ------------
 1 file changed, 12 deletions(-)

Patch

--- a/mm/page-writeback.c~mm-writeback-minor-clean-up-for-highmem_dirtyable_memory
+++ a/mm/page-writeback.c
@@ -324,18 +324,6 @@  static unsigned long highmem_dirtyable_m
 	}
 
 	/*
-	 * Unreclaimable memory (kernel memory or anonymous memory
-	 * without swap) can bring down the dirtyable pages below
-	 * the zone's dirty balance reserve and the above calculation
-	 * will underflow.  However we still want to add in nodes
-	 * which are below threshold (negative values) to get a more
-	 * accurate calculation but make sure that the total never
-	 * underflows.
-	 */
-	if ((long)x < 0)
-		x = 0;
-
-	/*
 	 * Make sure that the number of highmem pages is never larger
 	 * than the number of the total dirtyable memory. This can only
 	 * occur in very strange VM situations but we want to make sure