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 8934F846E for ; Mon, 18 Dec 2023 07:06:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RIj+CUHE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC08CC433C8; Mon, 18 Dec 2023 07:06:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1702883213; bh=xxWV2FBkSyuGl9JRUOHoSWsviIjCPjai3h2HRb2wNNs=; h=Subject:To:Cc:From:Date:From; b=RIj+CUHETrfPoU50Lp26/8eXL5EJnm/ENztZbc/whikC4PfkQSLGxF2wvcIIfpFWI 0r9qdKD9PkID2hKh6MWg1MQDDFBmfFrHWAEzg5g2KXQF+CEes3Wdp2cCQ066g5ORS2 eLjLfPRw4HSswUMaTA9QVBXThHsriawLA+tUHrQk= Subject: FAILED: patch "[PATCH] mm/damon/core: make damon_start() waits until kdamond_fn()" failed to apply to 6.1-stable tree To: sj@kernel.org,acsjakub@amazon.de,akpm@linux-foundation.org,changbin.du@intel.com,stable@vger.kernel.org Cc: From: Date: Mon, 18 Dec 2023 08:06:50 +0100 Message-ID: <2023121849-ambulance-violate-e5b2@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 6376a824595607e99d032a39ba3394988b4fce96 # git commit -s git send-email --to '' --in-reply-to '2023121849-ambulance-violate-e5b2@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 6376a8245956 ("mm/damon/core: make damon_start() waits until kdamond_fn() starts") 4472edf63d66 ("mm/damon/core: use number of passed access sampling as a timer") 2f5bef5a590b ("mm/damon/core: update monitoring results for new monitoring attributes") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6376a824595607e99d032a39ba3394988b4fce96 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Fri, 8 Dec 2023 17:50:18 +0000 Subject: [PATCH] mm/damon/core: make damon_start() waits until kdamond_fn() starts The cleanup tasks of kdamond threads including reset of corresponding DAMON context's ->kdamond field and decrease of global nr_running_ctxs counter is supposed to be executed by kdamond_fn(). However, commit 0f91d13366a4 ("mm/damon: simplify stop mechanism") made neither damon_start() nor damon_stop() ensure the corresponding kdamond has started the execution of kdamond_fn(). As a result, the cleanup can be skipped if damon_stop() is called fast enough after the previous damon_start(). Especially the skipped reset of ->kdamond could cause a use-after-free. Fix it by waiting for start of kdamond_fn() execution from damon_start(). Link: https://lkml.kernel.org/r/20231208175018.63880-1-sj@kernel.org Fixes: 0f91d13366a4 ("mm/damon: simplify stop mechanism") Signed-off-by: SeongJae Park Reported-by: Jakub Acs Cc: Changbin Du Cc: Jakub Acs Cc: # 5.15.x Signed-off-by: Andrew Morton diff --git a/include/linux/damon.h b/include/linux/damon.h index ab2f17d9926b..e00ddf1ed39c 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -559,6 +559,8 @@ struct damon_ctx { * update */ unsigned long next_ops_update_sis; + /* for waiting until the execution of the kdamond_fn is started */ + struct completion kdamond_started; /* public: */ struct task_struct *kdamond; diff --git a/mm/damon/core.c b/mm/damon/core.c index ce1562783e7e..3a05e71509b9 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -445,6 +445,8 @@ struct damon_ctx *damon_new_ctx(void) if (!ctx) return NULL; + init_completion(&ctx->kdamond_started); + ctx->attrs.sample_interval = 5 * 1000; ctx->attrs.aggr_interval = 100 * 1000; ctx->attrs.ops_update_interval = 60 * 1000 * 1000; @@ -668,11 +670,14 @@ static int __damon_start(struct damon_ctx *ctx) mutex_lock(&ctx->kdamond_lock); if (!ctx->kdamond) { err = 0; + reinit_completion(&ctx->kdamond_started); ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d", nr_running_ctxs); if (IS_ERR(ctx->kdamond)) { err = PTR_ERR(ctx->kdamond); ctx->kdamond = NULL; + } else { + wait_for_completion(&ctx->kdamond_started); } } mutex_unlock(&ctx->kdamond_lock); @@ -1433,6 +1438,7 @@ static int kdamond_fn(void *data) pr_debug("kdamond (%d) starts\n", current->pid); + complete(&ctx->kdamond_started); kdamond_init_intervals_sis(ctx); if (ctx->ops.init)