From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: dev@dpdk.org, yliu@fridaylinux.org, tiwei.bie@intel.com,
jianfeng.tan@intel.com, vkaplans@redhat.com
Cc: stable@dpdk.org, jfreiman@redhat.com
Subject: Re: [dpdk-dev] [PATCH v2 2/3] vhost: protect dirty logging against logging base change
Date: Tue, 28 Nov 2017 11:06:15 +0100 [thread overview]
Message-ID: <06080f95-a65a-a449-1c47-72b9d4d53122@redhat.com> (raw)
In-Reply-To: <20171124180826.18439-3-maxime.coquelin@redhat.com>
On 11/24/2017 07:08 PM, Maxime Coquelin wrote:
> When performing live-migration with multiple queue pairs,
> VHOST_USER_SET_LOG_BASE request is sent multiple times.
>
> If packets are being processed by the PMD threads, it is
> possible that they are setting bits in the dirty log map while
> its region is being unmapped by the vhost-user protocol thread.
> It results in the following crash:
> Thread 3 "lcore-slave-2" received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0x7f71ca495700 (LWP 32451)]
> 0x00000000004bfc8a in vhost_set_bit (addr=0x7f71cbe18432 <error: Cannot access memory at address 0x7f71cbe18432>, nr=1) at /home/max/projects/src/mainline/dpdk/lib/librte_vhost/vhost.h:267
> 267 __sync_fetch_and_or_8(addr, (1U << nr));
>
> We can see the vhost-user protocol thread just did the unmap of the
> dirty log region when it happens.
>
> This patch prevents this by introducing a RW lock to protect
> the log base.
>
> Fixes: 54f9e32305d4 ("vhost: handle dirty pages logging request")
> Cc: stable@dpdk.org
>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
> lib/librte_vhost/vhost.c | 2 ++
> lib/librte_vhost/vhost.h | 14 +++++++++++---
> lib/librte_vhost/vhost_user.c | 4 ++++
> 3 files changed, 17 insertions(+), 3 deletions(-)
>
By clarifying the vhost-user spec, we may be able to avoid this lock and
just ignore the subsequent SET_LOG_BASE requests once
VHOST_F_LOG_ALL feature bit is set.
So let's just discard this series for now.
Maxime
next prev parent reply other threads:[~2017-11-28 10:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-24 18:08 [dpdk-dev] [PATCH v2 0/3] vhost: MQ live-migration fixes Maxime Coquelin
2017-11-24 18:08 ` [dpdk-dev] [PATCH v2 1/3] vhost: fix fd leak in VHOST_USER_SET_LOG_BASE Maxime Coquelin
2017-11-24 18:08 ` [dpdk-dev] [PATCH v2 2/3] vhost: protect dirty logging against logging base change Maxime Coquelin
2017-11-27 8:16 ` Victor Kaplansky
2017-11-27 8:27 ` Maxime Coquelin
2017-11-27 8:42 ` Victor Kaplansky
2017-11-27 9:00 ` Maxime Coquelin
2017-11-28 10:06 ` Maxime Coquelin [this message]
2018-02-14 2:03 ` Tan, Jianfeng
2018-02-14 7:52 ` Maxime Coquelin
2018-02-22 2:54 ` Tan, Jianfeng
2017-11-24 18:08 ` [dpdk-dev] [PATCH v2 3/3] vhost: don't invalidate vrings if new addresses are identical Maxime Coquelin
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