From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) (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 17A213B1EF2 for ; Tue, 15 Sep 2026 12:00:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=172.234.252.31 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789473615; cv=none; b=HVXox9IpuAfbyGy2icduvaYmLgHcPJgQHVTlZzkiDdccIXoIkU+aCAE/0jqfhovzx6tmsj7E8eBR+VM8Y7jhbZqUZeljG74d1/GvhwrAE8Pc1J1K8clwDDwjDipdEyeItMqjl6e4pL2qMCAqnaJ57uKvWBn0A2lTzzn40ILyGSU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789473615; c=relaxed/simple; bh=0eP19xTwq1gs87/BZQkRLyRVSM9Ti58VrfYSAa2jop4=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=HyyObSa8FC7DvcIJU2lmCbg0dD/GF/I8sFepa2qvVFtz2hAy3dTM6y61/z3Diav8ZudFvc4M8vJPULCfq7mOjRrunojXQ/wNZLaqzg1zYYfEBBZ93/rFnJsOqo82zhAn+9h/9/ibqxuqcoMgkldj9hUdPxs6aJo4pfEEtg0tsKA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org; spf=pass smtp.mailfrom=kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bdJ8EfCA; arc=none smtp.client-ip=172.234.252.31 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bdJ8EfCA" Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id C51DE41B2F; Tue, 15 Sep 2026 12:00:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D59F81F000FF; Tue, 15 Sep 2026 12:00:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789473613; bh=lkRrGN3tHH0vPXJQpfXyuI1f/hj84726OJ+wXiSAjkY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=bdJ8EfCAcKRLCnZZLr9KUFRKwzOp9HwWHqD8dKOgs2QECDixoCiY7OitpfSWybTgc GrKy8T3cB5cVyun9gMM4tiazPAmkuvnRoSJn20gDY30Pi6NZ2BlWie/yV3J02KVzmP +FdO4hMG7v/dI5BZjC8kuRbGxnY1BMC++7JlKDVKVVz2TBx0SWNpwMbRNY+KWbqJrn ewEE2svDPg32d5ej4oQppZf8rSJTrU4fXT0CFb4RwzIPHo6I6kwXfOXCr0tMaXJRUv nQKJqvUmQYSXF6bRUemMO3EjVCVESrcELW0g+JEeeCOWgYbp17E7wf+3S6taJJ6xjy asi0ByODbGixg== From: sashiko-bot@kernel.org Subject: Re: [PATCH RFC POC 18/50] xtensa: commit fds on syscall exit Reply-To: sashiko-reviews@lists.linux.dev To: "Christian Brauner" , "Linus Torvalds" Cc: linux-arm-msm@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-openrisc@vger.kernel.org, "Peter Zijlstra" , linux-hyperv@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Jens Axboe" , linuxppc-dev@lists.ozlabs.org, linux-gpio@vger.kernel.org, "David Airlie" , virtualization@lists.linux.dev, "Oleg Nesterov" , linux-alpha@vger.kernel.org, kexec@lists.infradead.org, "Ingo Molnar" , dri-devel@lists.freedesktop.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, "Jan Kara" , linux-um@lists.infradead.org, "Eugenio Perez" , "Jann Horn" , bpf@vger.kernel.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, =?utf-8?b?Q2hyaXN0aWFuIEJyYXVuZXIgKEFtdXRhYmxlKQ==?= , linux-snps-arc@lists.infradead.org, "Alexander Viro" , io-uring@vger.kernel.org, sparclinux@vger.kernel.org, linux-mips@vger.kernel.org, "Michael S. Tsirkin" In-Reply-To: <20260915-work-fd-reserve-unify-folded-v1-18-4d5217d6b246@kernel.org> References: <20260915-work-fd-reserve-unify-folded-v1-0-4d5217d6b246@kernel.org> <20260915-work-fd-reserve-unify-folded-v1-18-4d5217d6b246@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 15 Sep 2026 12:00:11 +0000 Message-Id: <20260915120011.D59F81F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-m68k@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Medium] xtensa: inconsistent mid-syscall ptrace exit tracing due to stal= e flags -- commit f64c69fbd6ff1a2ee8dd26645f9d56d2d371647e Author: Christian Brauner xtensa: commit fds on syscall exit Add TIF_FD_SLOTS and test it once the system call has stored its return value. A task that reserved descriptors uses the traced path. [ ... ] > diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S > index 272fff587907f..4b95f48736e6b 100644 > --- a/arch/xtensa/kernel/entry.S > +++ b/arch/xtensa/kernel/entry.S > @@ -1976,6 +1976,11 @@ ENTRY(system_call) > 1: /* regs->areg[2] =3D return_value */ > =20 > s32i abi_rv, abi_saved0, PT_AREG2 > + > + /* descriptors reserved by the syscall are committed in do_syscall_trac= e_leave */ > + GET_THREAD_INFO(a4, a1) > + l32i a4, a4, TI_FLAGS > + bbsi.l a4, TIF_FD_SLOTS, 1f > bnez abi_saved1, 1f [Severity: Medium] Does this introduce a regression leading to inconsistent ptrace observability? The exit path in system_call() dynamically checks TIF_FD_SLOTS from fresh thread flags (loaded into a4), but falls back to abi_saved1 for trace work. Earlier in system_call(), abi_saved1 is cached before executing the syscall: GET_THREAD_INFO(a4, a1) l32i abi_saved1, a4, TI_FLAGS movi a4, _TIF_WORK_MASK and abi_saved1, abi_saved1, a4 If a tracer attaches mid-syscall (e.g. using PTRACE_ATTACH on an Xtensa process currently blocked inside a system call), wouldn't the exit trace events be missed for most syscalls because abi_saved1 lacks the new flags, yet mysteriously be caught if the syscall happens to allocate a file descriptor (because TIF_FD_SLOTS is checked against the fresh TI_FLAGS)? Could we reload the fresh _TIF_WORK_MASK from thread_info here instead of relying on the stale abi_saved1 cache? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260915-work-fd-re= serve-unify-folded-v1-0-4d5217d6b246@kernel.org?part=3D18