From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 952982F747A; Thu, 27 Aug 2026 04:39:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787805598; cv=none; b=rwJq3jVLy8bmY6CFDo0DGLLOxzD6gtqT+NK5JYCYDGCasNU6UEQfEkUVfXb/njXQk3nHpAVG5kju8xVKoqC6LNeh/5xMaq0n3RGxjs2+l/1UmLR8qGaavYCDnZZnASsLaH5kXL5Br0DA/9C28dvTUl/8kvPeRl3XoItkiR5H3MM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787805598; c=relaxed/simple; bh=RHxIikPc7hergzh3NxifN9KYH5P4fU8Kqyx0Ch89eF8=; h=Date:To:From:Subject:Message-Id; b=LnyqeAik6DPfPpSJC7EvB9uIeDiXw0N1w2zTcf3NEzq5LUAYJm4hkeBFi96rmgMG4xMA/tneG9rSJTUxPXkflK9qo8MThYIX1tTabDV0VOC/0SM5zI3APaOxsjJzK4nHMXbe4O3cHJsfBuY3V/zVCO7HNKPT6gAjtRRbArPkrM0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=PTpg5rC7; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="PTpg5rC7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE7271F000E9; Thu, 27 Aug 2026 04:39:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1787805597; bh=G27fV0oynmgN/z73nxVrc4j5aydEc/NhC9AtYuFO95g=; h=Date:To:From:Subject; b=PTpg5rC7cYnCm9veMMtx9Lufn+MQQTWIKHL1+U4fEiBS6Bc2migbUhSSWx1HNW3oq dDrLrKZO5Q90ngX2QCR/yW3rUlgLN7MQc1g48+37L1sq65nOm06Gk6fx4Jub/q2dmQ s7MviiIIGP37y/6XoDXzJdAJ5b5f/0w0QDH/XdZA= Date: Wed, 26 Aug 2026 21:39:56 -0700 To: mm-commits@vger.kernel.org,yanquanmin1@huawei.com,stable@vger.kernel.org,sj@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-damon-core-initialize-damos_quota_goal-last_psi_total.patch added to mm-new branch Message-Id: <20260827043956.EE7271F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/damon/core: initialize damos_quota_goal->last_psi_total has been added to the -mm mm-new branch. Its filename is mm-damon-core-initialize-damos_quota_goal-last_psi_total.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-core-initialize-damos_quota_goal-last_psi_total.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: SJ Park Subject: mm/damon/core: initialize damos_quota_goal->last_psi_total Date: Wed, 26 Aug 2026 21:29:18 -0700 Patch series "mm/damon: fix wrong behaviors in DAMOS PSI goal and sysfs refresh_ms". PSI based DAMOS auto-tuning and DAMON sysfs refresh_ms file have bugs that can produce non critical but still unexpected behaviors. Fix the two bugs. This patch (of 2): When DAMOS_QUOTA_SOME_MEM_PSI_US metric damos quota goal is set, the PSI delta for the feedback loop is calculated using damos_quota_goal->last_psi_total. However, it is initialized only after the first feedback loop. The first iteration of the loop uses the uninitialized value. As a result, the feedback loop can change the effective quota in an unexpected way at the first iteration. The user impact of the issue is not big, because the issue impacts only the first iteration of the feedback loop. The feedback loop also has an internal cap of the quota adjustment. The wrong adjustment will soon be corrected over a few iterations. For this reason, doing no initialization at commit time was intentional. It is also explicitly commented. That said, nobody likes behaviors that are unexpected or difficult to be expected. Fixing it is also simple and not expensive. Initialize the field at the beginning of kdamond and each commit of SOME_MEM_PSI_US type quota goals. The issue was discovered [1] by Sashiko. Link: https://lore.kernel.org/20260827042920.93580-2-sj@kernel.org Link: https://lore.kernel.org/20260718005316.89585-1-sj@kernel.org [1] Fixes: 2dbb60f789cb ("mm/damon/core: implement PSI metric DAMOS quota goal") Signed-off-by: SJ Park Cc: Quanmin Yan Cc: # 6.9.x Signed-off-by: Andrew Morton --- mm/damon/core.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) --- a/mm/damon/core.c~mm-damon-core-initialize-damos_quota_goal-last_psi_total +++ a/mm/damon/core.c @@ -1122,6 +1122,9 @@ static void damos_commit_quota_goal_unio struct damos_quota_goal *dst, struct damos_quota_goal *src) { switch (dst->metric) { + case DAMOS_QUOTA_SOME_MEM_PSI_US: + dst->last_psi_total = damos_get_some_mem_psi_total(); + break; case DAMOS_QUOTA_NODE_MEM_USED_BP: case DAMOS_QUOTA_NODE_MEM_FREE_BP: dst->nid = src->nid; @@ -1143,7 +1146,6 @@ static void damos_commit_quota_goal( dst->target_value = src->target_value; if (dst->metric == DAMOS_QUOTA_USER_INPUT) dst->current_value = src->current_value; - /* keep last_psi_total as is, since it will be updated in next cycle */ damos_commit_quota_goal_union(dst, src); } @@ -3727,6 +3729,17 @@ static int kdamond_wait_activation(struc return -EBUSY; } +static void damos_init_quota_goal_last_psi(struct damos *s) +{ + struct damos_quota_goal *goal; + + damos_for_each_quota_goal(goal, &s->quota) { + if (goal->metric != DAMOS_QUOTA_SOME_MEM_PSI_US) + continue; + goal->last_psi_total = damos_get_some_mem_psi_total(); + } +} + static void kdamond_init_ctx(struct damon_ctx *ctx) { unsigned long sample_interval = ctx->attrs.sample_interval ? @@ -3743,6 +3756,7 @@ static void kdamond_init_ctx(struct damo damon_for_each_scheme(scheme, ctx) { damos_set_next_apply_sis(scheme, ctx); damos_set_filters_default_reject(scheme); + damos_init_quota_goal_last_psi(scheme); } } _ Patches currently in -mm which might be from sj@kernel.org are mm-damon-core-initialize-damos_quota_goal-last_psi_total.patch mm-damon-sysfs-set-next-refresh-jiffies-per-sysfs-context.patch