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 C44013FFE; Tue, 23 Jan 2024 00:48:57 +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=1705970937; cv=none; b=qLORBoMx1q02tqsHyaxsi305z6SNJZ7ZwD+xxPQZJ7ZU0at3ijLZuATdV+8bcXi8AIJzz+te6lcpkWI+m18w/dHgWstHlokOweEcnSGMpVT5bud7RVvjocmrBSdM8uqTu1kP6mf2RtgIyTexOLQb1dswL8ZpETbzIS6SfOiltTo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705970937; c=relaxed/simple; bh=VAhjB5lgdxLzRVJ6y1vox/0Qz2E+q7mqoYJ5XZ8g6H8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=diagY1D0uW14rq3FS9eDBGNhOhPaaeJJpjPp72pHE5cKrW2HPsNOUEAyCGmlAKKm1XKf5vOk7BWm3FuI2gi0b0BExAYg7kEdylK3LVVOF01R7c4cmvbTbZ1FdpktErIV5EOVo1XqnmxHAFpI3bam9sCGLnd93W8F0HQEbQzqGx4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=r3OhOQaz; 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="r3OhOQaz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D9B8C43390; Tue, 23 Jan 2024 00:48:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1705970937; bh=VAhjB5lgdxLzRVJ6y1vox/0Qz2E+q7mqoYJ5XZ8g6H8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r3OhOQaz01Afn01SGNt43vNSlC9DEvkAQtGGMvSnYMCkIO9DN2MEnLDbdtiN1ANQV QD0M/2GoBx0AfTIhzkPzfkrzLZFJoMi9DnP9eyvkzHB7tFCDBOnVqBomrAD9QIOUPF zqGwTpWQvIMWhd8W0l0HDLLwlS1CAgjfLp7UQNN0= 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 5.10 024/286] neighbour: Dont let neigh_forced_gc() disable preemption for long Date: Mon, 22 Jan 2024 15:55:30 -0800 Message-ID: <20240122235732.955186938@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240122235732.009174833@linuxfoundation.org> References: <20240122235732.009174833@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-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 4c43183a8d93..432e3a64dc4a 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -226,9 +226,11 @@ 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); @@ -251,11 +253,16 @@ 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