From: Jens Axboe <axboe@kernel.dk>
To: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Cc: wenxiong@linux.vnet.ibm.com, gpiccoli@linux.vnet.ibm.com,
hch@infradead.org, Brian King <brking@linux.vnet.ibm.com>,
Douglas Miller <dougmill@linux.vnet.ibm.com>,
linux-block@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH RESEND v2 2/2] blk-mq: Avoid memory reclaim when remapping queues
Date: Wed, 14 Dec 2016 08:14:26 -0700 [thread overview]
Message-ID: <d0e0367d-de9f-dd0c-7316-ccde65ac194b@kernel.dk> (raw)
In-Reply-To: <1481038304-22502-2-git-send-email-krisman@linux.vnet.ibm.com>
On 12/06/2016 08:31 AM, Gabriel Krisman Bertazi wrote:
> While stressing memory and IO at the same time we changed SMT settings,
> we were able to consistently trigger deadlocks in the mm system, which
> froze the entire machine.
>
> I think that under memory stress conditions, the large allocations
> performed by blk_mq_init_rq_map may trigger a reclaim, which stalls
> waiting on the block layer remmaping completion, thus deadlocking the
> system. The trace below was collected after the machine stalled,
> waiting for the hotplug event completion.
>
> The simplest fix for this is to make allocations in this path
> non-reclaimable, with GFP_NOIO. With this patch, We couldn't hit the
> issue anymore.
This looks fine.
--
Jens Axboe
next prev parent reply other threads:[~2016-12-14 15:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-06 15:31 [PATCH RESEND v2 1/2] blk-mq: Fix failed allocation path when mapping queues Gabriel Krisman Bertazi
2016-12-06 15:31 ` [PATCH RESEND v2 2/2] blk-mq: Avoid memory reclaim when remapping queues Gabriel Krisman Bertazi
2016-12-07 20:10 ` Douglas Miller
2016-12-14 15:14 ` Jens Axboe [this message]
2016-12-07 20:06 ` [PATCH RESEND v2 1/2] blk-mq: Fix failed allocation path when mapping queues Douglas Miller
2016-12-07 20:12 ` Douglas Miller
2016-12-14 15:13 ` Jens Axboe
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