From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH stable v3.2 v3.4] ipv4: disable bh while doing route gc Date: Mon, 13 Oct 2014 13:51:27 -0400 (EDT) Message-ID: <20141013.135127.1915115817707962111.davem@davemloft.net> References: <6c3d6eca5d6a15c01393b010f2116bd169477c5a.1413215324.git.mleitner@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: stable@vger.kernel.org, netdev@vger.kernel.org, hannes@stressinduktion.org To: mleitner@redhat.com Return-path: In-Reply-To: <6c3d6eca5d6a15c01393b010f2116bd169477c5a.1413215324.git.mleitner@redhat.com> Sender: stable-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Marcelo Ricardo Leitner Date: Mon, 13 Oct 2014 14:03:30 -0300 > Further tests revealed that after moving the garbage collector to a work > queue and protecting it with a spinlock may leave the system prone to > soft lockups if bottom half gets very busy. > > It was reproced with a set of firewall rules that REJECTed packets. If > the NIC bottom half handler ends up running on the same CPU that is > running the garbage collector on a very large cache, the garbage > collector will not be able to do its job due to the amount of work > needed for handling the REJECTs and also won't reschedule. > > The fix is to disable bottom half during the garbage collecting, as it > already was in the first place (most calls to it came from softirqs). > > Signed-off-by: Marcelo Ricardo Leitner > Acked-by: Hannes Frederic Sowa > Acked-by: David S. Miller > Cc: stable@vger.kernel.org -stable folks, please integrate this directly, thanks!