From: Tejun Heo <tj@kernel.org>
To: NeilBrown <neilb@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kernfs: use stack-buf for small writes.
Date: Tue, 23 Sep 2014 00:12:58 -0400 [thread overview]
Message-ID: <20140923041258.GA27067@mtj.dyndns.org> (raw)
In-Reply-To: <20140923140633.35efbe7a@notabene.brown>
Hello, Neil.
On Tue, Sep 23, 2014 at 02:06:33PM +1000, NeilBrown wrote:
> When mdmon needs to update metadata after a device failure in an array
> there are two 'kmalloc' sources that can trigger deadlock if memory is tight
> and needs to be written to the array (which cannot be allowed until mdmon
> updates the metadata).
> One is in O_DIRECT writes which I have patches for. The other is when
> writing to the sysfs file to tell md that it is safe to continue.
> This simple patch removes the second.
Ugh... :( If this can't be avoided at all, I'd much prefer it to be
something explicit - a flag marking the file as needing a persistent
write buffer which is allocated on open. "Small" writes on stack
feels way to implicit to me.
Thanks.
--
tejun
next prev parent reply other threads:[~2014-09-23 4:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-23 4:06 [PATCH] kernfs: use stack-buf for small writes NeilBrown
2014-09-23 4:12 ` Tejun Heo [this message]
2014-09-23 4:18 ` Tejun Heo
2014-09-23 4:46 ` NeilBrown
2014-09-23 4:55 ` Tejun Heo
2014-09-23 5:40 ` NeilBrown
2014-09-23 5:51 ` Tejun Heo
2014-09-23 6:11 ` NeilBrown
2014-09-23 6:15 ` Tejun Heo
2014-09-24 19:17 ` Al Viro
2014-09-24 23:58 ` NeilBrown
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