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 E45232475CE; Fri, 27 Mar 2026 01:17:49 +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=1774574270; cv=none; b=SmT0pZBxt7CVEqIuqbfUHLF7FlE2pJ9GhlJcIFfjOXkuMEH/7rrl87XhAzCyIQW8HyKZ4DgTEx53EQai1HYrqaNNuOg0xamIUzo7M0KA3/ZxKnqArGyo2XuS4TeP0zccWr3pjC9gXrRq3yD3ra1Sq+aKa9FIkDtRhKEe4EeqbLY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774574270; c=relaxed/simple; bh=Fj+wzq/6iKYICFkTGU/r8tL7mIACYw3BRf1GTOTNh94=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Jfavmm0WUsPFhMrVWKo5gdrHxG8eGRoSlUaHOMvkjCoTPIMrvCv7z+HA77eC4yBZZk3gSbz+MYv7fw254xKEF+DWAv6gs+3X29X7JxjT5akC0LaHjWO+0He3KTWftrzBMGKy7mf+EM4grC7jzTylSvcNVCz3vLr5jxl1FtKQbUI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N8wbJjBq; 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="N8wbJjBq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 622C3C116C6; Fri, 27 Mar 2026 01:17:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774574269; bh=Fj+wzq/6iKYICFkTGU/r8tL7mIACYw3BRf1GTOTNh94=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N8wbJjBqfUz1iZ2pyro304QYGXMLlo329AaeIw2pH/rYmSXhksT98yYQxIsqmd/md hSCuS1AclGoRsOQIWSn67Xp/JXgSdsXyMQ8WQkQATgKC9sb5DNhFEYcpcM5z0K48Dh YUXQ57CH0WqKbdty5tYJDAn0+5Oq8vf6mtQ7au+iYM9i3g/+SjN48XvPjzmJTSymbj cnFWpHCq4IWFJqPPquXDsSRd/F3uhzxqfXO87YO7nYFZK3VaYvrYApCH1zlAtfIAvI 9tEY3RuglpzUiojnhamHfDdVxRImwkuhqWcaMWYVF3m4QNFvKD9sG9bzVNKdFnTVaI orhB8UPMLOUbg== From: SeongJae Park To: SeongJae Park Cc: Andrew Morton , "# 6 . 17 . x" , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: (sashiko review) [PATCH] mm/damon/sysfs: dealloc repeat_call_control if damon_call() fails Date: Thu, 26 Mar 2026 18:17:47 -0700 Message-ID: <20260327011747.66127-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260327003224.55752-1-sj@kernel.org> References: Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Forwarding Sashiko review for doing discussions via mails. # review url: https://sashiko.dev/#/patchset/20260327003224.55752-1-sj@kernel.org # start of sashiko.dev inline review commit aba7f94d0accfda5ab9b573157f691de9e9acf00 Author: SeongJae Park mm/damon/sysfs: dealloc repeat_call_control if damon_call() fails This commit attempts to fix a memory leak where repeat_call_control is not deallocated if damon_call() fails because the kdamond stopped before the invocation. It adds a check to free repeat_call_control when damon_call() returns an error. Link: https://lore.kernel.org/20260320020630.962-1-sj@kernel.org > diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c > index 6a44a2f3d8fc..eefa959aa30a 100644 > --- a/mm/damon/sysfs.c > +++ b/mm/damon/sysfs.c > @@ -1670,7 +1670,8 @@ static int damon_sysfs_turn_damon_on(struct damon_sysfs_kdamond *kdamond) > repeat_call_control->data = kdamond; > repeat_call_control->repeat = true; > repeat_call_control->dealloc_on_cancel = true; > - damon_call(ctx, repeat_call_control); > + if (damon_call(ctx, repeat_call_control)) > + kfree(repeat_call_control); Does this fully resolve the leak of repeat_call_control? If a sysfs writer thread calls damon_call() during kdamond shutdown, after the worker thread in kdamond_fn() flushes pending controls but before it sets ctx->kdamond = NULL: kdamond_fn() kdamond_call(ctx, true); ... // Before ctx->kdamond = NULL Would damon_call() add the new request to ctx->call_controls and return 0 since ctx->kdamond is not yet NULL and repeat is true? If so, does this leave repeat_call_control in the queue and leaked since the worker is already exiting and this check is bypassed? Could this same window also cause a deadlock for synchronous commands like DAMON_SYSFS_CMD_UPDATE_SCHEMES_STATS? If a synchronous command with repeat = false is added to the queue during this same window, would the caller hang indefinitely on wait_for_completion() since the worker thread will never process the queue again? > return err; > } # end of sashiko.dev inline review # review url: https://sashiko.dev/#/patchset/20260327003224.55752-1-sj@kernel.org # # hkml [1] generated a draft of this mail. It can be regenerated # using below command: # # hkml patch sashiko_dev --for_forwarding \ # 20260327003224.55752-1-sj@kernel.org # # [1] https://github.com/sjp38/hackermail Sent using hkml (https://github.com/sjp38/hackermail)