From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=193.142.43.55 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793637345; b=XzhxeRbyUl0hk4fou+7yLRTDXLL97talOrpaM+utffwjcR2ZEH7zvGvEQygwZLmjykYu i9THBDG48qKrKdpW/fIwIIkFlWBu6X9J/vdlT76r/sT+0sRkcR4XdsYaaaBz8/dTagVBf rCoF1OCQJ++6fVsCimabTNcoTIYqi+e/0iqRzHEw32Y5xIqpqxi5ioo1UguWeMsiVJnpp ylTGz5Dkz1OZBA0nI5hm8x5Y+kNb40drusHEfPDQHd0Nanoj3XVk2wX6Dmxp6vur3MCA5 4gOXySrP/HYtI1EZqYd2O9qvPNHFBLT39R8LrIPYnLAmPtXksnARBMuR44AfWsXO1Tw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793637345; h=DMARC-Filter:Date:DKIM-Signature:DKIM-Signature:From:To:Cc:Subject: Message-ID:References:MIME-Version:Content-Type:Content-Disposition: In-Reply-To; bh=HcwaI3pW/80H6haxw0NcngNpoXS0R7BCzSXcfAhrIDU=; b=a7QAHXL5Y+o6sK9ZyWGHcZItVxmq3YypH17oFzXADwMIrOAgLB5CZ4V5ej9O9Yl8kG5Y 0rR3XA13F2LDuWn1fynf3Qn9xXXrr60XIJhRPLlV/dL5zbVsOzhFp+QJJ7dlY/k0begsO +V5pf4aNAz5opCcgCXDo4Xryw+mnEBHU2A8cbw5jU+ijfYn7hfJHUCa/h57DxViYMItpT 5B37V1kznVduE6t2KpyOo/06MDr0NXHw4dJ22I12Pq91EykJQ35Z2dsgVifmjsQ2dubUS YJmKpELBjA/Qsfqvnf5YYQLu4g9gynRrFAquVXpdDHYmKIh4+ls80lRcAvaFZvAtbrg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b="xU/AoOCF"; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=8bnDqeXu; arc=none smtp.remote-ip=193.142.43.55 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DCA49606B0F0; Mon, 2 Nov 2026 16:35:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org DCA49606B0F0 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=xU/AoOCF; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=8bnDqeXu Date: Mon, 2 Nov 2026 17:35:40 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1793637342; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=HcwaI3pW/80H6haxw0NcngNpoXS0R7BCzSXcfAhrIDU=; b=xU/AoOCFrBJ15PVVJBmI69ViObjB++CB/yEAfN1yWlRzwYLhKo7BmRzYNPYBssmxv13M4M gQONHXowsfenN4yxEZLjIYWX0TAWqZnAitz5ReX7ym7kE1Km6VcptYzx80hpSyIfty8S9i Ius+rnm9W/eTYwwP6t/K+JjFpiyGYyHxBqcu+NCFZ0YIPEd3kFlh/1oAi55sWmRLS8A0v6 c7IDGEtl1641adTXs3M3m1iuo0kS0JBZDTLdAABvXp5CuzeaoWedLyQTES7epgkaQ3atq0 s8kwVSC2gi9p/bk7dQnapTuMZmi9LC5hybWEAXgte0EJjJW0zTRCsFlueGnZKQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1793637342; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=HcwaI3pW/80H6haxw0NcngNpoXS0R7BCzSXcfAhrIDU=; b=8bnDqeXul1VM/geD8d3muGIQ8dthuMTSJ+51XIR0TeSbW+SjPjz/Ig1lAmFBJ6FUCe9wbH UgrqUvkQG5/89vCQ== From: Sebastian Andrzej Siewior To: Tengda Wu Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf/core: Prevent duplicate sigtrap task work enqueue Message-ID: <20261102163540.4WF7hhhW@linutronix.de> References: <20261031114520.642476-1-wutengda@huaweicloud.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20261031114520.642476-1-wutengda@huaweicloud.com> On 2026-10-31 11:45:20 [+0000], Tengda Wu wrote: > The sigtrap handling in __perf_event_overflow() checks > event->pending_work before calling task_work_add(), but only sets > pending_work after the task work has been queued. > > This leaves a window where an NMI can interrupt task_work_add() > and re-enter __perf_event_overflow() for the same event. Since > pending_work is still zero, the nested invocation can enqueue > the same pending_task again. > > The re-entrant call path is: > > __perf_event_overflow() > task_work_add() > kasan_record_aux_stack() > > __perf_event_overflow() > task_work_add() How was the issue identified? Sebastian