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From: SeongJae Park <sj@kernel.org>
Cc: SeongJae Park <sj@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	damon@lists.linux.dev, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: [RFC PATCH v1.1 06/13] mm/damon/core: remove damon_warn_fix_nr_accesses_corruption()
Date: Sat, 20 Jun 2026 10:22:36 -0700	[thread overview]
Message-ID: <20260620172244.90953-7-sj@kernel.org> (raw)
In-Reply-To: <20260620172244.90953-1-sj@kernel.org>

nr_accesses_bp is delicate.  Once it is corrupted, the consequence is
the bad madness of DAMON monitoring results.  From developments of
features of size, we historically found nr_accesses_bp can be corrupted
by complicated bugs that are not easy to debug.  Hence we added a
function for finding the corruption and fixing it right away.

There are no more uses of nr_accesses_bp.  Hence the function for
corruption detection and fix is no more needed.  Rip it out.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index 710ec13e98281..e144f0079322d 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1994,19 +1994,6 @@ int damos_walk(struct damon_ctx *ctx, struct damos_walk_control *control)
 	return 0;
 }
 
-/*
- * Warn and fix corrupted ->nr_accesses[_bp] for investigations and preventing
- * the problem being propagated.
- */
-static void damon_warn_fix_nr_accesses_corruption(struct damon_region *r)
-{
-	if (r->nr_accesses_bp == r->nr_accesses * 10000)
-		return;
-	WARN_ONCE(true, "invalid nr_accesses_bp at reset: %u %u\n",
-			r->nr_accesses_bp, r->nr_accesses);
-	r->nr_accesses_bp = r->nr_accesses * 10000;
-}
-
 #ifdef CONFIG_DAMON_DEBUG_SANITY
 static void damon_verify_reset_aggregated(struct damon_region *r,
 		struct damon_ctx *c)
@@ -2048,7 +2035,6 @@ static void kdamond_reset_aggregated(struct damon_ctx *c)
 			trace_damon_aggregated(ti, r, damon_nr_regions(t));
 			trace_damon_region_aggregated(ti, r,
 					damon_nr_regions(t), nr_probes);
-			damon_warn_fix_nr_accesses_corruption(r);
 			r->last_nr_accesses = r->nr_accesses;
 			r->nr_accesses = 0;
 			for (i = 0; i < DAMON_MAX_PROBES; i++)
-- 
2.47.3

  parent reply	other threads:[~2026-06-20 17:23 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-20 17:22 [RFC PATCH v1.1 00/13] mm/damon: optimize out nr_accesses_bp SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 01/13] mm/damon: introduce damon_nr_accesses_mvsum() SeongJae Park
2026-06-20 17:36   ` sashiko-bot
2026-06-20 17:39     ` SeongJae Park
2026-06-20 17:41       ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 02/13] mm/damon/tests/core-kunit: test damon_mvsum() SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 03/13] mm/damon/core: use damon_nr_accesses_mvsum() in __damos_valid_target() SeongJae Park
2026-06-20 17:41   ` sashiko-bot
2026-06-20 18:07     ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 04/13] mm/damon/core: use damon_nr_accesses_mvsum() for damos region tracing SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 05/13] mm/damon/sysfs-schemes: use damon_nr_accesses_mvsum() for damo regions SeongJae Park
2026-06-20 17:37   ` sashiko-bot
2026-06-20 18:19     ` SeongJae Park
2026-06-20 17:22 ` SeongJae Park [this message]
2026-06-20 17:22 ` [RFC PATCH v1.1 07/13] mm/damon/core: remove damon_verify_reset_aggregated() SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 08/13] mm/damon/core: remove damon_verify_merge_regions_of() SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 09/13] mm/damon/tests/core-kunit: remove nr_accesses_bp setup and tests SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 10/13] selftests/damon/drgn_dump_damon_status: do not dump nr_accesses_bp SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 11/13] mm/damon/core: remove nr_accesses_bp setups and updates SeongJae Park
2026-06-20 17:34   ` sashiko-bot
2026-06-20 17:45     ` SeongJae Park
2026-06-20 18:20       ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 12/13] mm/damon/core: remove damon_moving_sum() and its unit test SeongJae Park
2026-06-20 17:35   ` sashiko-bot
2026-06-20 17:47     ` SeongJae Park
2026-06-20 17:22 ` [RFC PATCH v1.1 13/13] mm/damon: remove damon_region->nr_accesses_bp SeongJae Park

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