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 6D940484230 for ; Tue, 13 Oct 2026 04:32:51 +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=1791865972; cv=none; b=NpC0fD8gYZRMGcKCvNxtTFNVEF+4LECixGaWmvgIWamI1//qBBNsVIt0/SR6QBDNbadV8YIBrDBjv1RLY+qSu4KahMQqSTkNoK/d6kCuk7mY1ePTaX5LZBaoSu8oecbm6JvfCG4QYge9oD0M24mnQXP1ZWnJCKDaAkR/5MSGKfs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791865972; c=relaxed/simple; bh=O8UVcvhxtNzeIVJ+ZH83uJhIc/vzcyS+WErRB4fkPLg=; h=Date:To:From:Subject:Message-Id; b=c+yKShdVG/NtR0fe5ZlDfUZ02J6agTPcrm8LTjHYDgiiUpUszIzxlAARFtIvxvF8f01dHDwq/N1JXZiege8Z6HnF4E6qgRHcPKKY3dC4N0CKknckwjgKtvrlJ+IgvRuHBqgjHQZhS7hXYSnv420d3V+dfCtv4VihKrkqnKQFWfw= 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=OOAa+7If; 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="OOAa+7If" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 425B11F00898; Tue, 13 Oct 2026 04:32:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791865971; bh=odq2E4ER7/VwhvPDFk5oCI911OyKXVc2MxvoUfqFEsI=; h=Date:To:From:Subject; b=OOAa+7IfQLZT71KQSkKXLYPUCqbejt6VtKEFHUTV9sksFSDHR0LgCt45/7qMebvM8 JU3POxIftHhIIFDqztU6fseJv7DFVi4TgKvibaXJ1blA/hIUdx7CdURnCD9Vlz8jn6 YjlKK3i9Xdr1/8Elu6hayTvRVVZ9+wEMTwKcxz5w= Date: Mon, 12 Oct 2026 21:32:50 -0700 To: mm-commits@vger.kernel.org,vbabka@kernel.org,surenb@google.com,shuah@kernel.org,rppt@kernel.org,rdunlap@infradead.org,mhocko@suse.com,ljs@kernel.org,liam@infradead.org,gutierrez.asier@huawei-partners.com,david@kernel.org,davidgow@davidgow.net,corbet@lwn.net,brendan.higgins@linux.dev,sj@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-damon-core-document-damon_call-damon_start-race-hang-issue.patch removed from -mm tree Message-Id: <20261013043251.425B11F00898@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm/damon/core: document damon_call()/damon_start() race hang issue has been removed from the -mm tree. Its filename was mm-damon-core-document-damon_call-damon_start-race-hang-issue.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: SJ Park Subject: mm/damon/core: document damon_call()/damon_start() race hang issue Date: Thu, 17 Sep 2026 07:22:03 -0700 Let's suppose damon_start() and damon_call() are executed in parallel for the same DAMON context. Then, damon_call() could show ctx->damon_calls_obsolete set while ctx->kdamond is unset. If damon_start() sets ctx->kdamond before damon_call() starts the cancelling, damon_call() can indefinitely hang. No DAMON API caller does such parallel execution of damon_start() and damon_call(), so the issue doesn't exist. But who knows what will happen in future. Add a clarification comment for caution. Link: https://lore.kernel.org/20260917142210.90829-6-sj@kernel.org Signed-off-by: SJ Park Signed-off-by: Andrew Morton Cc: Asier Gutierrez Cc: Brendan Higgins Cc: David Gow Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Randy Dunlap Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka --- mm/damon/core.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/damon/core.c~mm-damon-core-document-damon_call-damon_start-race-hang-issue +++ a/mm/damon/core.c @@ -2258,6 +2258,9 @@ int damon_kdamond_pid(struct damon_ctx * * * When this function is failed, the @ctx is guaranteed to be stopped. * + * This function should not be called in parallel to damon_start() for the + * @ctx. In the case, this function could indefinitely hang. + * * Return: 0 on success, negative error code otherwise. */ int damon_call(struct damon_ctx *ctx, struct damon_call_control *control) _ Patches currently in -mm which might be from sj@kernel.org are mm-damon-core-introduce-damos_quota_goal-complement.patch mm-damon-core-add-complement-argument-to-damos_new_quota_goal.patch mm-damon-sysfs-schemes-support-quota-goal-complement-flag.patch mm-damon-tests-core-kunit-test-quota_goal-complement-commit.patch selftests-damon-sysfssh-test-quota-goal-complement-flag-file.patch docs-mm-damon-design-document-damos-quota-goal-complement-flag.patch docs-admin-guide-mm-damon-usage-update-for-quota-goal-complement-file.patch docs-abi-damon-update-for-quota-goal-metric-complement-sysfs-file.patch