From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (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 042AA1757D; Sat, 13 Jul 2024 17:16:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=96.67.55.147 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720891016; cv=none; b=q0+bO1zDMVbVBr4x/KfIsb4A273lCTiqxM1KOR6p/2uW0JhH2/ENz33UDJ40A7WXDzPBAOo5eKMNhpvtWmYZWT/PNUrBaIebdqJgGHSkoLlo1qUj+ph74vgkgJtD+Y4Nxe6NdvmMog20J/yI8x88cTq2NQE9OIn+iYnlnRW9664= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720891016; c=relaxed/simple; bh=yvecYwcOCWC8daVyn2D3EoAxG9h0nFQH4t1J3vkDOyY=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=oQ699xMITp5Qu9HHJji+l9K1BAEfYgOdAfkE+tPzfFWdRzYoLn2kQy3xGMlm2VtKbqReF7CGitLu/Ne5qvtzCq3tpGY7ZXlWQ+cIXB8XSi8pWYuoiqqt0kdKK9o7YRSb7L8wI+urUcRZY3Lv+Hq87yM+K8Onh7Xfk/gNSfirXhY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=surriel.com; spf=pass smtp.mailfrom=shelob.surriel.com; arc=none smtp.client-ip=96.67.55.147 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=surriel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=shelob.surriel.com Received: from [2601:18c:9101:a8b6:6e0b:84ff:fee2:98bb] (helo=imladris.surriel.com) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from ) id 1sSgMZ-000000000DQ-2AT0; Sat, 13 Jul 2024 13:16:47 -0400 Message-ID: Subject: Re: [PATCH 2/3] locking/csd_lock: Provide an indication of ongoing CSD-lock stall From: Rik van Riel To: neeraj.upadhyay@kernel.org, linux-kernel@vger.kernel.org Cc: rcu@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, mingo@kernel.org, peterz@infradead.org, paulmck@kernel.org, leobras@redhat.com, imran.f.khan@oracle.com Date: Sat, 13 Jul 2024 13:16:47 -0400 In-Reply-To: <20240713165846.216174-2-neeraj.upadhyay@kernel.org> References: <20240713165642.GA215331@neeraj.linux> <20240713165846.216174-2-neeraj.upadhyay@kernel.org> Autocrypt: addr=riel@surriel.com; prefer-encrypt=mutual; keydata=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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.4 (3.50.4-1.fc39) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: riel@surriel.com On Sat, 2024-07-13 at 22:28 +0530, neeraj.upadhyay@kernel.org wrote: >=20 > @@ -228,6 +241,7 @@ static bool > csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, in > =C2=A0 cpu =3D csd_lock_wait_getcpu(csd); > =C2=A0 pr_alert("csd: CSD lock (#%d) got unstuck on > CPU#%02d, CPU#%02d released the lock.\n", > =C2=A0 *bug_id, raw_smp_processor_id(), cpu); > + atomic_dec(&n_csd_lock_stuck); > =C2=A0 return true; > =C2=A0 } > =C2=A0 So we decrement it when it gets unstuck. Good. > @@ -251,6 +265,8 @@ static bool > csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, in > =C2=A0 pr_alert("csd: %s non-responsive CSD lock (#%d) on CPU#%d, > waiting %lld ns for CPU#%02d %pS(%ps).\n", > =C2=A0 firsttime ? "Detected" : "Continued", *bug_id, > raw_smp_processor_id(), (s64)ts_delta, > =C2=A0 cpu, csd->func, csd->info); > + if (firsttime) > + atomic_dec(&n_csd_lock_stuck); >=20 However, I don't see any place where it is incremented when things get stuck, and this line decrements it when a CPU gets stuck for the first time? Should this be an atomic_inc? --=20 All Rights Reversed.