From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 609FA2D1303; Tue, 28 Apr 2026 01:34:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777340070; cv=none; b=jaL7ByWwuXCpB9xHMX+c7Itl+Uru7SUsomujv9Wp0h+pgA2UrAEihyNr8VxmErLxNwB2Z7ZP2oHM/Qjl6huqEwhXcQPiY2/bEOhM3EjtvXs4103tbvw+2+yYOex4KKs+9jnSVvkoz7pFjVJvNG54TeeUGxVMnPPg4SdZZnSbJBo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777340070; c=relaxed/simple; bh=CbuuRamb/kBQi30M9xcMQJVCapHdXjhxNpZwhqf9TZk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YaMaMod/ZmgXKcDY1mkhksL9NPhN2/XpyW4+FAl0quxB7B1GhAXNB8wdP94t2ZF8ehizQNkfBg1yRWp4uHenPjkCYKWq9PwYpqU+W+RJY473QfG3NytmMWOZzW45thhPR0Z109tEjmXXiNN5W7V0nC28N46Q4eDArpSElicSdVs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=omaAhUye; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="omaAhUye" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE879C2BCB9; Tue, 28 Apr 2026 01:34:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777340070; bh=CbuuRamb/kBQi30M9xcMQJVCapHdXjhxNpZwhqf9TZk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=omaAhUyegFAJx3SDDZ9s6uKHSs/OVhumd7gScii7OT1kQ86yFeNfP5NwgoHvIi0Dt XSPF8wfv0S6k4KUlhaggo5kuqmaygpeNULxi/ncPJvGr90Xp5gHBZweo6qHTrhfQf5 MrzZ5BI3Wlk9Z2GZrc0czpa4kR/MwTjcwdlSBuTsqUDFOIN4UBX6W73zRd5eZo2DvP oE/lUwrLarSIlVJ3NAmzIsnKbmVuFO34UzAWcT89kd7lRAwO+KtLAUhpDkUV89zUD8 Q2peGg4FMIeuO5NtZ4h0VRVGL0F68DzRi0CmCmPZrmsfLCv8MgZW/SQFvGB8FClP95 viYG76miNhlPg== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 01/11] mm/damon/core: handle X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260428013402.115171-1-sj@kernel.org> References: <20260428013402.115171-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Less than min_region_sz remaining quota effectively means the quota is fully charged. In other words, no remaining quota. This is because DAMOS actions are applied in the region granularity, and each region should have min_region_sz or larger size. However the existing fully charged quota check, which is also used for setting charge_target_from and charge_addr_from of the quota, is not aware of the case. For the reason, charge_target_from and charge_addr_from of the quota will not be updated in the case. This can result in DAMOS action being applied more frequently to a specific area of the memory. The case is unreal because quota charging is also made in the region granularity. It could be changed in future, though. Actually, the following commit will make the change, by allowing users to set arbitrary quota charging ratio for action-failed regions. To be prepared for the change, update the fully charged quota checks to treat having less than min_region_sz remaining quota as fully charged. Signed-off-by: SeongJae Park --- mm/damon/core.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 278594847cf94..888b6ac29feff 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2047,6 +2047,20 @@ static void damos_walk_cancel(struct damon_ctx *ctx) mutex_unlock(&ctx->walk_control_lock); } +static bool damos_quota_is_full(struct damos_quota *quota, + unsigned long min_region_sz) +{ + if (!damos_quota_is_set(quota)) + return false; + if (quota->charged_sz >= quota->esz) + return true; + /* + * DAMOS action is applied per region, so esz - quota->charged_sz < min_region_sz; +} + static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, struct damon_region *r, struct damos *s) { @@ -2104,8 +2118,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, quota->total_charged_ns += timespec64_to_ns(&end) - timespec64_to_ns(&begin); quota->charged_sz += sz; - if (damos_quota_is_set(quota) && - quota->charged_sz >= quota->esz) { + if (damos_quota_is_full(quota, c->min_region_sz)) { quota->charge_target_from = t; quota->charge_addr_from = r->ar.end + 1; } @@ -2133,8 +2146,7 @@ static void damon_do_apply_schemes(struct damon_ctx *c, continue; /* Check the quota */ - if (damos_quota_is_set(quota) && - quota->charged_sz >= quota->esz) + if (damos_quota_is_full(quota, c->min_region_sz)) continue; if (damos_skip_charged_region(t, r, s, c->min_region_sz)) @@ -2460,8 +2472,7 @@ static void damos_adjust_quota(struct damon_ctx *c, struct damos *s) if (!time_in_range_open(jiffies, quota->charged_from, quota->charged_from + msecs_to_jiffies(quota->reset_interval))) { - if (damos_quota_is_set(quota) && - quota->charged_sz >= quota->esz) + if (damos_quota_is_full(quota, c->min_region_sz)) s->stat.qt_exceeds++; quota->total_charged_sz += quota->charged_sz; quota->charged_from = jiffies; -- 2.47.3