From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793213909; b=qveplQR81q5SxhFOejeFi6dBtF+tnaLc9DhWe2G1Nuin7sYsoiv9X5tRKr+zPs5NW+iA a0/C3wGlCFM4UwvAitYc7ThQf68eOVZsUd9mMZhjeQ4VgDfYbgz+mgo959Hj+xLknrGNi Fonu31ifruegXxFm4emp+f3Q9NJWKJRsSroX4UEQGsp9F2WrgQpCOcivG2crOH/7XnbrD /otz/WviKiT93l+OBADLDcP5PMsLEi4dA7N3mQuhrQ850yZGMJthhDXFuTmgbnTnsBlYy Dcel2KpsbV24mwkOKPFHmYayI22iveFYUkfJ0UXwzP0IDdB8bVkB/LBtLOXKllpJRbQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793213909; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=uf3t67xqN4kzKxjl1rbyGpBAEIKTE0EOK2mNmRmXm7U=; b=T6z2CjtprqIcd/bbIWauRF7sjPgsvgK+KkbtjSaQTM4OdcOipB/x5Tk71aRtRVEc8RHV 1SUdxUJ6eOp6pM0ZFEeqoLjfn3XJh+ywWbgIXUfOBbcpAi50SPSQ53JWn2CwtCQe4hYuZ uVhThqlPGD/oJOU/UepYgx90hd9WeWkHp0gbl65Epap/pGc8A+ITZXJTx10FPaw2fm6LK hKf6cEhjd8QSQYSEFh3I4viVIkWxFLJORErFPxP+RIvbYA1RsSlG1rcRCRVINYvtq2lPl PbvFXYlouSg1+oKX5s4Vs3aAyooQMi1fEXQrSfGEeOwZhucRZ5Gi4Cm3w7JZ3QBKOuw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=XeQ3yHYA; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 02E3B606A31A; Wed, 28 Oct 2026 18:58:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=XeQ3yHYA Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51F5C1F01825; Wed, 28 Oct 2026 18:58:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793213908; bh=uf3t67xqN4kzKxjl1rbyGpBAEIKTE0EOK2mNmRmXm7U=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XeQ3yHYAMr/cnXXvzUH4oypR6R57+cxM2qG5kFCm4xnCjbvvPxSWeMIOKyyPJzchp 2tKKTucsuV+NOTQBH61bZnUjNvMWwjXPF5HG7QL42zUchn2yxZrVXbb0c2vM+wJlBr mcviz4oUasnxHqZMIPYbJxi7+PpZXKdfG3RFaioQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wander Lairson Costa , "Peter Zijlstra (Intel)" , Juri Lelli , Sasha Levin Subject: [PATCH 6.1 0629/1887] sched/deadline: Fix task_struct reference leak Date: Wed, 28 Oct 2026 17:45:25 +0100 Message-ID: <20261028170513.722312843@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wander Lairson Costa [ Upstream commit b58652db66c910c2245f5bee7deca41c12d707b9 ] During the execution of the following stress test with linux-rt: stress-ng --cyclic 30 --timeout 30 --minimize --quiet kmemleak frequently reported a memory leak concerning the task_struct: unreferenced object 0xffff8881305b8000 (size 16136): comm "stress-ng", pid 614, jiffies 4294883961 (age 286.412s) object hex dump (first 32 bytes): 02 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 .@.............. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ debug hex dump (first 16 bytes): 53 09 00 00 00 00 00 00 00 00 00 00 00 00 00 00 S............... backtrace: [<00000000046b6790>] dup_task_struct+0x30/0x540 [<00000000c5ca0f0b>] copy_process+0x3d9/0x50e0 [<00000000ced59777>] kernel_clone+0xb0/0x770 [<00000000a50befdc>] __do_sys_clone+0xb6/0xf0 [<000000001dbf2008>] do_syscall_64+0x5d/0xf0 [<00000000552900ff>] entry_SYSCALL_64_after_hwframe+0x6e/0x76 The issue occurs in start_dl_timer(), which increments the task_struct reference count and sets a timer. The timer callback, dl_task_timer, is supposed to decrement the reference count upon expiration. However, if enqueue_task_dl() is called before the timer expires and cancels it, the reference count is not decremented, leading to the leak. This patch fixes the reference leak by ensuring the task_struct reference count is properly decremented when the timer is canceled. Fixes: feff2e65efd8 ("sched/deadline: Unthrottle PI boosted threads while enqueuing") Signed-off-by: Wander Lairson Costa Signed-off-by: Peter Zijlstra (Intel) Acked-by: Juri Lelli Link: https://lore.kernel.org/r/20240620125618.11419-1-wander@redhat.com Signed-off-by: Sasha Levin --- kernel/sched/deadline.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 62a7c4ed86753..83204e5b780e4 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1689,8 +1689,12 @@ static void enqueue_task_dl(struct rq *rq, struct task_struct *p, int flags) * The replenish timer needs to be canceled. No * problem if it fires concurrently: boosted threads * are ignored in dl_task_timer(). + * + * If the timer callback was running (hrtimer_try_to_cancel == -1), + * it will eventually call put_task_struct(). */ - hrtimer_try_to_cancel(&p->dl.dl_timer); + if (hrtimer_try_to_cancel(&p->dl.dl_timer) == 1) + put_task_struct(p); p->dl.dl_throttled = 0; } } else if (!dl_prio(p->normal_prio)) { -- 2.53.0