From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B2928606D830 for ; Sun, 8 Nov 2026 20:28:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=gfNPdoBK Received: by kanga.kvack.org (Postfix) id 0C8A66B05B6; Sun, 8 Nov 2026 15:28:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 07F7D6B05B7; Sun, 8 Nov 2026 15:28:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E82636B05B8; Sun, 8 Nov 2026 15:28:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id B78606B05B6 for ; Sun, 8 Nov 2026 15:28:10 -0500 (EST) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 39124A80ED for ; Sun, 8 Nov 2026 20:28:10 +0000 (UTC) X-FDA: 85413088740.08.59D9A51 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf24.hostedemail.com (Postfix) with ESMTP id A2C29180002 for ; Sun, 8 Nov 2026 20:28:08 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=gfNPdoBK; spf=pass (imf24.hostedemail.com: domain of sj@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1794169688; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Z5j7HhXnzELbkFkJqEZQNTDWxIhKaeKvJLsv/O41RlA=; b=AeHtivv+UszTqADQ2FUdu8tyFkETec5SntSuKm4ekQ1T8XKfQ/yuXw39dbypoyiEIAyAoe tcwJ0ZV9ncGz/ff4DvM48m9UIxa+4XSiUJvDEJxYclEy5y6mDr0sZe5L8LCWy/LvuhbLoT EdDYN3/dsnU3eyMuZXrV+wfw3MKQt+Y= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794169688; b=42axdGvdeSZksnNzOuys5ZVUqXgwLpJ82Uyio20LfvwfwOebxaRidAAndaR4uYv5YJUxwI p1WkYtory3fd4FOxDV8L7aEmtb6EKCUXCqpo52GcOytjUHHiwuit14gbf2BbLUUJCtvjVw q+VQAw01wndRTFW4kowtq5OWwMvBa2M= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=gfNPdoBK; spf=pass (imf24.hostedemail.com: domain of sj@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 3F4AF61DD7; Sun, 8 Nov 2026 20:28:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C0F7B1F008BD; Sun, 8 Nov 2026 20:28:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794169688; bh=Z5j7HhXnzELbkFkJqEZQNTDWxIhKaeKvJLsv/O41RlA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gfNPdoBKXcAtf6hRjx3oBKNvxuctMSQpp/iU/H5+S3lFaJwT4pILePYk9ynCAGLLH ZQJ8bqirTCcBOaXloqpNaEz2VKMDfqtY8wq4tMkfj7Ehg8JKLyIxP6QwEiN/8RBgm3 zXrTuKZvl5Vrr23sVgTtroZLOxmzLMKXtdCYkWpY2T7PclwpuiIUqThyvEPj8VvwKm DKqLyBO6KsoAsvY50IdhNuQicPCA+ngvurlEjB2UN3IXpMRho/hJneE4TnKedvnJhC ehL1nyF63OVVy5QiPeDpZl6kbiEl0Xs2vCWKJueP591ZB0wWAHb9+2Eqsz54sXK6pX 7YEr5HJQOZm6w== From: SJ Park To: stable@vger.kernel.org Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 6.1.y 2/2] mm/damon/core: remove unreachable damos charge_{target,addr}_from Date: Sun, 8 Nov 2026 12:27:58 -0800 Message-ID: <20261108202759.117377-3-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261108202759.117377-1-sj@kernel.org> References: <20261108202759.117377-1-sj@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Stat-Signature: zq9u36js4o7xp4uqdpj6jbztamze8q9d X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Queue-Id: A2C29180002 X-Rspam-User: X-HE-Tag: 1794169688-17757 X-HE-Meta: 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 WGeAIZrq iv4nsLGxoDpYnDZfUBtICum+nyPnK7a62jsVPEwgHjOGFhqItPzve3miSQAD9qToja83wGMmDOBDS/emAAa0Lihu+D5VxcRH0BS4lIwUpveTEHLIzAQ4aE0PtkHVG0yXNz7+oVM9TFOQz4nbak7Ey4mwRtw+BG9IvYQfO+Ny9oZnDoTR9/aRGdAUbHPPjy7UjJcOrG19f/nelZpEkZx//5mHX6nZt+Ph1ddP7FT3NrDQqf2j2TZ3KiU99EGNWOLZrxOm5o6Kh9vDuQLvUFr4W0dxIPbDB2VQVRAAzTqi0XSI/h3nhz33mK1aKctjL3o/+2Jq+HzPTCxIm6onomfKBrzn1ikCJb+7Zi7xSPvM+5NyfmdijKa8/MI7dSe7L27OAK/aKupu0kGVBHN4= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 damos_quota->charge_{target,addr}_from saves the target and region the scheme's quota limit is reached. damos_skip_charged_region() skips the target and regions before the point. The target that was assigned to charge_target_from could be dynamically removed from the context by the runtime parameters update (aka commit) feature. In this case, damos_skip_charged_region() cannot find if the point is passed or not, so the scheme is effectively disabled. Similarly, the user could also remove all the regions of the target using the runtime parameters update feature. It would be uncommon to do that, but it is a supported feature. Because the skip pointer detection logic (damos_skip_charged_region()) works for each region of targets, this result in the logic is entirely skipped and the scheme is effectively disabled again. The user impact is that the DAMOS scheme could suddenly stop working under certain uses of the runtime parameters update feature. It could surprise users. No crash or leak happens though. Users could also simply work around by re-installing the scheme. Catch the corner cases in damos_adjust_quota() and reset the pointers. Link: https://lore.kernel.org/20261020023958.108276-1-sj@kernel.org Fixes: da87878010e5 ("mm/damon/sysfs: support online inputs update") Signed-off-by: SJ Park Signed-off-by: Andrew Morton Closes: https://sashiko.dev/#/bug/linux-cd0c55fc-0cc8-45d8-9637-3334811c49b8 Cc: # 5.19.x (cherry picked from commit 5695abc4e742b947f586bfb6a080a80ad9957e5d) Signed-off-by: SJ Park --- mm/damon/core.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 9206737d05ae7..01f93146b92fe 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -860,6 +860,26 @@ static void damos_set_effective_quota(struct damos_quota *quota) quota->esz = esz; } +static void damos_fix_stale_charge_pointers(struct damon_ctx *c, + struct damos *s) +{ + struct damos_quota *quota; + struct damon_target *t; + + quota = &s->quota; + if (!quota->charge_target_from) + return; + damon_for_each_target(t, c) { + if (t == quota->charge_target_from) { + if (damon_nr_regions(t) > 0) + return; + break; + } + } + quota->charge_target_from = NULL; + quota->charge_addr_from = 0; +} + static void kdamond_apply_schemes(struct damon_ctx *c) { struct damon_target *t; @@ -890,6 +910,8 @@ static void kdamond_apply_schemes(struct damon_ctx *c) damos_set_effective_quota(quota); } + damos_fix_stale_charge_pointers(c, s); + if (!c->ops.get_scheme_score) continue; -- 2.47.3