From: Daniel Wagner <dwagner@suse.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
Steve Wise <swise@opengridcomputing.com>,
Leon Romanovsky <leon@kernel.org>,
Potnuri Bharat Teja <bharat@chelsio.com>
Subject: Re: [PATCH] nvme: Drop WQ_MEM_RECLAIM flag from core workqueues
Date: Tue, 13 Apr 2021 10:54:04 +0200 [thread overview]
Message-ID: <20210413085404.tzam5lprtspwcek4@beryllium.lan> (raw)
In-Reply-To: <20210412130402.GF227011@ziepe.ca>
On Mon, Apr 12, 2021 at 10:04:02AM -0300, Jason Gunthorpe wrote:
> Basically the allocation of importance in the workqueue is assigning a
> worker, so pre-allocating a worker ensures the work can continue to
> progress without becoming dependent on allocations.
Ah okay, got it. I didn't really understood this part. So the
WQ_MEM_RECLAIM is 'just' avoiding a new worker creation.
> This is why work under the WQ_MEM_RECLAIM cannot recurse back into the
> allocator as it would get a rescurer thread stuck at a point when all
> other threads are already stuck.
>
> To remove WQ_MEM_RECLAIM you have to make assertions about the calling
> contexts and blocking contexts of the workqueue, not what the work
> itself is doing.
Hmm, I am struggling with your last statement. If a worker does an
allocation it might block. I understand this is something which a worker
in a WQ_MEM_RECLAIM context is not allowed to do.
My aim is still to get rid of the warning triggered by the rdma
code.
Anyway, thanks for explaining.
_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme
next prev parent reply other threads:[~2021-04-13 8:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 12:23 [PATCH] nvme: Drop WQ_MEM_RECLAIM flag from core workqueues Daniel Wagner
2021-04-12 12:31 ` Jason Gunthorpe
2021-04-12 12:49 ` Daniel Wagner
2021-04-12 13:04 ` Jason Gunthorpe
2021-04-13 8:54 ` Daniel Wagner [this message]
2021-04-13 13:35 ` Jason Gunthorpe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210413085404.tzam5lprtspwcek4@beryllium.lan \
--to=dwagner@suse.de \
--cc=axboe@fb.com \
--cc=bharat@chelsio.com \
--cc=hch@lst.de \
--cc=jgg@ziepe.ca \
--cc=kbusch@kernel.org \
--cc=leon@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvme@lists.infradead.org \
--cc=sagi@grimberg.me \
--cc=swise@opengridcomputing.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).