From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 4FD292EC081 for ; Sun, 13 Sep 2026 03:36:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789270612; cv=none; b=DTx+WyEr/3+KmfzrZordMkXv0gVEerUIre0zCcqgI0EITsR23J/6ETjLa9+464uWOsb+xgZK9tdMUEmkBLg+6Tcw8dzd8F5D5Q9SHCiE8fSa/r0gmJbNFUQ0xKyR3FKUYwBJLE48mvt9lPqr+/e/1YPSn01rntIfiZhFOH/i1rk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789270612; c=relaxed/simple; bh=a3i0lrNcseLSdqG/zFZuAFMU1WINqm0WXqHIwD0k45w=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=khd4KaH8OVtLW1NbcFxpZ7F7DwvRI/dkzawW6PIYxy6yvy9ReYODWjzu1LMKMJJUkOFMidMNkDiFa5TNAMIshUiduH3KeSaqXpTPOgavPkVPw7UnKCQetpVGAFz0sazzimPGx8IUYdbGfRYzEMd50oW4pTWxvoEDWcIMSFp7sY0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XJpsu2MH; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XJpsu2MH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A94751F000FF; Sun, 13 Sep 2026 03:36:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789270610; bh=2A61qLG/JJQmMPXAHffiR4BZPA2jRdhO7Bi9LLX/pQs=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=XJpsu2MHpoLVGlJC4Bz0D/gfS+VE0VSZNkyKdu2pmCBKfCUwbNr6DxraYZIpzrFVl AqNKCWbvHPrZJ05iyVTnssWf8elgf+PXyvXaeC2FyruKGv+bwiFAs+iBj8uOebTNif 5ZOcRt0NASRxBIzoyJELOkvr04ovyugNxpPPUU2bdR9k+QFSPe/37kIb9jayTGgDh2 gyDuWjEjRxts9+r6uyL0rezPeNioB533PKa8MkcKtF22Uw/jDr9wW7QweuNczp7PjL VrfD6Q9oYK4KDQ4rji7+AWuKXD5WNjr9uA8fCCD/jL5Sj4oGnE7n6HJoSW9QBuKSW5 +ZQgBvrLa9F8Q== From: sashiko-bot@kernel.org Subject: Re: [PATCH v2 3/8] perf symbol: Fall back to fetching the vmlinux by build ID Reply-To: sashiko-reviews@lists.linux.dev To: "Arnaldo Carvalho de Melo" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20260913032632.116277-4-acme@kernel.org> References: <20260913032632.116277-1-acme@kernel.org> <20260913032632.116277-4-acme@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sun, 13 Sep 2026 03:36:50 +0000 Message-Id: <20260913033650.A94751F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@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] Holding `dso->lock` across a blocking debuginfod network fetch c= auses lock starvation. -- commit 0a14099ecb356d49e5d4b366cbd27b6a6caf40b8 Author: Arnaldo Carvalho de Melo perf symbol: Fall back to fetching the vmlinux by build ID This commit adds a fallback mechanism to fetch the vmlinux keyed by its bui= ld ID using the debuginfod client when local kernel symbols cannot be found. > diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c > --- a/tools/perf/util/symbol.c > +++ b/tools/perf/util/symbol.c [ ... ] > +static int dso__load_vmlinux_build_id(struct dso *dso, struct map *map) > +{ > + char *path =3D NULL; > + > + if (!dso__has_build_id(dso)) > + return -1; > + > + if (debuginfo__find_build_id(dso__bid(dso), &path)) [Severity: Medium] Does holding the dso lock across this debuginfod network fetch cause lock starvation? When a perf profile is missing local kernel symbols, dso__load() acquires dso->lock and subsequently calls dso__load_kernel_sym(), which then calls dso__load_vmlinux_build_id(). This results in the blocking call to debuginfo__find_build_id() executing while dso->lock is still held. Could a slow network fetch or timeout stall all concurrent accesses to the same kernel DSO by other threads, potentially impacting tool responsiveness (such as in perf top) or parallel processing? > + return -1; > + > + /* Takes ownership of 'path' even when it fails */ > + return dso__load_vmlinux(dso, map, path, true); > +} [ ... ] --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260913032632.1162= 77-1-acme@kernel.org?part=3D3