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From: SeongJae Park <sj@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: SeongJae Park <sj@kernel.org>,
	"# 5 . 16 . x" <stable@vger.kernel.org>,
	damon@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: [PATCH] mm/damon/core: make charge_addr_from aware of end-address exclusivity
Date: Mon, 27 Apr 2026 21:29:40 -0700	[thread overview]
Message-ID: <20260428042942.118230-1-sj@kernel.org> (raw)

DAMON region end address is exclusive one, but charge_addr_from is
assigned assuming the end address is inclusive.  As a result, DAMOS
action to next up to min_region_sz memory can be skipped.  This is quite
negligible user impact.  But, the bug is a bug that can be very simply
fixed.  Fix the wrong assignment to respect the exclusiveness of the
address.

The issue was discovered [1] by Sashiko.

[1] https://lore.kernel.org/20260428032324.115663-1-sj@kernel.org

Fixes: 50585192bc2e ("mm/damon/schemes: skip already charged targets and regions")
Cc: <stable@vger.kernel.org> # 5.16.x
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 278594847cf94..37c9a40d0577b 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -2107,7 +2107,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t,
 		if (damos_quota_is_set(quota) &&
 				quota->charged_sz >= quota->esz) {
 			quota->charge_target_from = t;
-			quota->charge_addr_from = r->ar.end + 1;
+			quota->charge_addr_from = r->ar.end;
 		}
 	}
 	if (s->action != DAMOS_STAT)

base-commit: 986c714ac6faa9750e15ccaec72ff2823c96a5c6
-- 
2.47.3


                 reply	other threads:[~2026-04-28  4:29 UTC|newest]

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