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imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Z86lqUUM; spf=pass (imf25.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788875680; b=u5i9NwkRaEJT5fq4Jvv2eoR5Cwf2B11gAsrxAKeTysUB8I/nvHiyaJ3WtUscbr6LLpdHcO kbVXgZeED0wyql3YcTeqBjR/4U8FMrGxTXp39+OT9BrgZrpKHoy9IQs5NpcTCisXDVbD7B Ne5XOsApKNJ3OWKTtLOolV8NQSIeo/8= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 22F2C43C2C; Tue, 8 Sep 2026 13:54:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C39851F00A3A; Tue, 8 Sep 2026 13:54:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788875679; bh=CgoRG7kKCzhkx46Y0+lhAJX5PsX1/GyoeuyPyR0dxwo=; h=From:To:Cc:Subject:Date; b=Z86lqUUMYk7rbhqAZ9Zo3V48PT6WAZS89KSYGDOwN27qGsZ1M+LhuJrs9Zpu5DvFd GW1l/FqbXXw5u2E/TYJMNHJ2R1J0BXwYfuZCUm+He6fr5EH9REzvqiHVCVx3tQDydS BOak43kkjbizFAtOn1wR8hUkT+/1iN3EmeuXbLHxy/9b717qQ/I39p8r8j6bfiYJbh SzLlXRZb+/928FB050/Wnt8jgzSbYXDhTC6Dmvmv9eSdGDBBNtX84BvMFfaOfA8eoa nwAyYF7+WvVC4q4FiKMSSMQPWJBFprVg5hc6+Gs3PeKTUwipvEg/QsUJ8aLz9kzDDz 4+3PLFLuk9Dow== From: SJ Park To: Andrew Morton Cc: Liew Rui Yan , stable@vger.kernel.org, SJ Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v4] mm/damon/core: allow esz to be set to zero Date: Tue, 8 Sep 2026 06:54:11 -0700 Message-ID: <20260908135413.97570-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E9340A0007 X-Stat-Signature: icmrwp1dpmrixupxmixsxo3puor3353x X-Rspam-User: X-HE-Tag: 1788875679-196938 X-HE-Meta: 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 KbI6TPcf zQM8DBniVH67TeVIauotASTL590D7fzB0OlRnC9oKVZ+BcAMdKBBpp9iEvVDN4k/aXTBU8Y6IYcSSFcYAfah/YS14rCo/y6RCMacQi3lhGmd6jmfzBVeDLyH+rA+VWFIh9ZA20PGp26D9xuPGtZB6A3c2iOMXVLmxsefgkU17iAaEdAkQoaO2QSDgo2jw7hemKpgzcdw8czuuCshj4Pq850eOETUGyNkrx4GDS3hzfslUaeSkN/qHqzbFAHLfJg4Pr28HfKYno+KMf8pxfj8j0Qh9sKOE04vwj56syz4pCqs97GFqYgLbvv0aPw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Liew Rui Yan When the temporal quota goal tuner determines that the goal has been achieved (score >= 10000), it sets esz_bp to zero so that the esz becomes zero. However, damos_set_effective_quota() clamps the esz to min_region_sz when quota->ms is set. This is a minor issue, the main problem is that it doesn't match the description in the documentation, which state that if the goal has already been [over-]achieved, the quota will be set to zero. Fix this by set quota (esz) as minimum as possible. Fixes: 8bbde987c2b8 ("mm/damon/core: disallow time-quota setting zero esz") Cc: # v7.1.x Cc: Andrew Morton Signed-off-by: Liew Rui Yan Reviewed-by: SJ Park Signed-off-by: SJ Park --- Changes from v3: - v3: https://lore.kernel.org/20260905124706.3398-1-aethernet65535@gmail.com - Collect R-b: from SJ. Changes from v2: - v2: https://lore.kernel.org/damon/20260902082050.19566-1-aethernet65535@gmail.com - Changed implementation, more general implementation provided by SJ. [1] [1] https://lore.kernel.org/damon/20260902150301.88535-1-sj@kernel.org Changes from v1: - v1: https://lore.kernel.org/damon/20260901105951.106246-1-aethernet65535@gmail.com - Changed implementation. The initial solution skipped the min_region_sz clamping when esz was already zero. However, this would revert the fix from commit 8bbde987c2b8 and cause a regression. This revision fixes the issue by adding a specific check for a zero esz_bp. - Changed patch title, original title: fix quota could not be set to zero mm/damon/core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 7e6cd405161d4..06cf2ab7e97d7 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -3242,6 +3242,7 @@ static void damos_set_effective_quota(struct damon_ctx *ctx, struct damos *s) struct damos_quota *quota = &s->quota; unsigned long throughput; unsigned long esz = ULONG_MAX; + unsigned long esz_time; if (!quota->ms && list_empty("a->goals)) { quota->esz = quota->sz; @@ -3262,8 +3263,8 @@ static void damos_set_effective_quota(struct damon_ctx *ctx, struct damos *s) 1000000, quota->total_charged_ns); else throughput = PAGE_SIZE * 1024; - esz = min(throughput * quota->ms, esz); - esz = max(ctx->min_region_sz, esz); + esz_time = max(throughput * quota->ms, ctx->min_region_sz); + esz = min(esz_time, esz); } if (quota->sz && quota->sz < esz) base-commit: 6f8c7324e336e626bd993bc36f177dcf493a871f -- 2.47.3