From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F0CB120DD54; Mon, 16 Jun 2025 15:51:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750089073; cv=none; b=MW/glM35z+PNe3y3ifa+6slltq4pabPFXwDCZiVXHjfyIkCG6lPKkCdCfKvhwaEHoD8rCeje6fgXKVOIttsGl12/kfUuz4wR3a+870maf40OXT4grNng+tF9TiLThSQocn9Y13eFeNBkxHFD4MNEP/+Re3UI8N4HjMbTbCTgiJU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750089073; c=relaxed/simple; bh=1IQ346zNYVuM6lRx+3Lxg56eImhlMLA0oHvWP0r94kA=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=CfYCesVanDafqvApQSgmRgdlPHoeHAH89fRgrwABS0eXPx4O4KF69Y0GK7ubMPOjm+O/C+pipCRJYrEYXMWPrlbZJ+GlfsM4UJxkCDmszjQ7aQbwNCoGgEewW5KQ4r+bjiVPOjhp7zHLgoQX2EjVHXcTZuQyaz+e2r+KmISSrRk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ABlsFso4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ABlsFso4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8169DC4CEF8; Mon, 16 Jun 2025 15:51:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750089072; bh=1IQ346zNYVuM6lRx+3Lxg56eImhlMLA0oHvWP0r94kA=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=ABlsFso4LatrwE13U8Tbb+tm5+R3hqaDkMZM6jlcXooiAVtTO1wRpYqVzfSEyciGe TRJ2F+/c2VgzaAQilK21b5eKaidhYqGsVQWYK1kJHTdXOKYpoOitgFnLcrbNcfTHBL Wipbje2urmd/GAlqADLbBaMS45343VrXJN2iU+Ilu+lgcnGQLt3lsUWKsJG6atp/NV 3pU2cdk7ejq0WMKO6YbaI6WQDPdP2kgsilKtfZcf2aCDwS7ujkjH38wPYRPP7C27oV JpXqQC4iPJDgJYeq32FkDI/5hn1Biz+SyzI2NghJQ8ssjQj8gWAHSJEEXcsJcm9jVI sfvIsBjmiR14Q== Received: by mail-qt1-f181.google.com with SMTP id d75a77b69052e-4a44b3526e6so62870291cf.0; Mon, 16 Jun 2025 08:51:12 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCWIU7rKKEHXLNVbppDKsEZPOxpjKxMOYiWMb2DVvkH8gnWOibqfbtNPaRH20Ip9XeLQJcQ=@vger.kernel.org, AJvYcCXBEV8ukEhD0aoj25ZO/lGy15CHNv7B2qTxIjKCBkUAkcsLB8akJ1ykGLR2myWac8dRQnM6WAZVT7zz5Cxa@vger.kernel.org X-Gm-Message-State: AOJu0YzzEZo3uwx0m6QqZfzP0i8e30UsThki1fI3VjS6vaOsRAOXQ9H2 7+MqB1YHh+TMcgBkWKZ7uj/iYIySSqlnNyehWPOY1GIdDn/0uf8tN1gfKcdZWapbtt/b2Wm6B01 3pw61wWCaYcNs0Ek9iVmE9Q0imw1FGlQ= X-Google-Smtp-Source: AGHT+IEruSD9QNTjLoQwJZZefnA/4WRHh7lO5AJIHFCUDpHpP+t8W6jXHMulp+dSHEV0ihSgIt6cozsKO9xdrVpRX+k= X-Received: by 2002:ac8:7fcb:0:b0:472:1d98:c6df with SMTP id d75a77b69052e-4a73c5c3447mr162424511cf.52.1750089071562; Mon, 16 Jun 2025 08:51:11 -0700 (PDT) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250616095532.47020-1-matt@readmodwrite.com> In-Reply-To: <20250616095532.47020-1-matt@readmodwrite.com> From: Song Liu Date: Mon, 16 Jun 2025 08:50:58 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: AX0GCFvUaE9dttZdJBdvpTmPqrf3iG2pJ0W7olm9JHra97Bg2gJGxgUnrlZedhk Message-ID: Subject: Re: [PATCH] bpf: Call cond_resched() to avoid soft lockup in trie_free() To: Matt Fleming Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@cloudflare.com, Matt Fleming Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Jun 16, 2025 at 2:55=E2=80=AFAM Matt Fleming wrote: > > From: Matt Fleming > > Calls to kfree() in trie_free() can be expensive for KASAN-enabled > kernels. This can cause soft lockup warnings when traversing large maps, I think this could also happen to KASAN-disabled kernels, so the commit log is a bit misleading. > > watchdog: BUG: soft lockup - CPU#41 stuck for 76s! [kworker/u518:14:115= 8211] > > Avoid an unbounded loop and periodically check whether we should reschedu= le. > > Signed-off-by: Matt Fleming Other than that: Acked-by: Song Liu > --- > kernel/bpf/lpm_trie.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c > index be66d7e520e0..a35619cd99f6 100644 > --- a/kernel/bpf/lpm_trie.c > +++ b/kernel/bpf/lpm_trie.c > @@ -646,6 +646,8 @@ static void trie_free(struct bpf_map *map) > RCU_INIT_POINTER(*slot, NULL); > break; > } > + > + cond_resched(); > } > > out: > -- > 2.34.1 >