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 909711420A7; Tue, 23 Jan 2024 01:08:38 +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=1705972118; cv=none; b=TUGECm3Bbo06kVPiaV/5lP3VEp+kjEYg7Ov5aEDUYb2sqZB9ol7guE5+U/xqtXhljHrm4Bv76pK7zqqAzpCnNdEZD6/VAfWABD0R/77kydrx8T/WE31a9GZZf8tuw6gwS24rsCZ+b2Wf/Hhb5gV16Bsc84L/gcF3Aw/K6UwO7Qw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705972118; c=relaxed/simple; bh=7jq9Bj0J01V3NWPNk46+xBdaahRC76FA3UjPFsZzOyw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MlTCR6zFByp1a57rq+iyq0PWwVZrYJPaDTe3iY2btGoDVLFjrI1Ha4js0WmSXWp69s56qaAoIRJmosi6DU1DO6XEG2vNO5/L1fAOE1elFdKbjsrrdvxhX3ourncrdQBcr22sNDlZYPQc+jafK+6YovsgnMX1Kr0uTbf2pToAG28= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=D9JZDF+q; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="D9JZDF+q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F05EC43399; Tue, 23 Jan 2024 01:08:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1705972118; bh=7jq9Bj0J01V3NWPNk46+xBdaahRC76FA3UjPFsZzOyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D9JZDF+q3KuMORncsNDuxJOzo+CHd7FrqF4QD9v5jTLkG7RfignzH0uc64nxUxoSL y0R1vsI4nwh78swPVvyg2Il7ITnGK3sT7ecFhOPd7HZetgD+hAVISBbZW+Em5Vj6qd AaqzOjZ5vUEmL5Snq/n5w/LjRnoTrS9F7tt+yFf0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Douglas Anderson , Judy Hsiao , David Ahern , Eric Dumazet , "David S. Miller" , Sasha Levin Subject: [PATCH 5.15 028/374] neighbour: Dont let neigh_forced_gc() disable preemption for long Date: Mon, 22 Jan 2024 15:54:44 -0800 Message-ID: <20240122235745.616749539@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240122235744.598274724@linuxfoundation.org> References: <20240122235744.598274724@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Judy Hsiao [ Upstream commit e5dc5afff62f3e97e86c3643ec9fcad23de4f2d3 ] We are seeing cases where neigh_cleanup_and_release() is called by neigh_forced_gc() many times in a row with preemption turned off. When running on a low powered CPU at a low CPU frequency, this has been measured to keep preemption off for ~10 ms. That's not great on a system with HZ=1000 which expects tasks to be able to schedule in with ~1ms latency. Suggested-by: Douglas Anderson Signed-off-by: Judy Hsiao Reviewed-by: David Ahern Reviewed-by: Eric Dumazet Reviewed-by: Douglas Anderson Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/core/neighbour.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 927c4db2703f..5829477efbba 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -225,9 +225,11 @@ static int neigh_forced_gc(struct neigh_table *tbl) { int max_clean = atomic_read(&tbl->gc_entries) - READ_ONCE(tbl->gc_thresh2); + u64 tmax = ktime_get_ns() + NSEC_PER_MSEC; unsigned long tref = jiffies - 5 * HZ; struct neighbour *n, *tmp; int shrunk = 0; + int loop = 0; NEIGH_CACHE_STAT_INC(tbl, forced_gc_runs); @@ -250,11 +252,16 @@ static int neigh_forced_gc(struct neigh_table *tbl) shrunk++; if (shrunk >= max_clean) break; + if (++loop == 16) { + if (ktime_get_ns() > tmax) + goto unlock; + loop = 0; + } } } WRITE_ONCE(tbl->last_flush, jiffies); - +unlock: write_unlock_bh(&tbl->lock); return shrunk; -- 2.43.0