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From: David Laight <David.Laight@ACULAB.COM>
To: 'Josef Bacik' <josef@toxicpanda.com>, "hch@lst.de" <hch@lst.de>,
	"viro@ZenIV.linux.org.uk" <viro@ZenIV.linux.org.uk>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kernel-team@fb.com" <kernel-team@fb.com>
Subject: RE: [PATCH] proc: use vmalloc for our kernel buffer
Date: Thu, 13 Aug 2020 16:19:27 +0000	[thread overview]
Message-ID: <714c8baabe1a4d0191f8cdaf6e28a32d@AcuMS.aculab.com> (raw)
In-Reply-To: <20200813145305.805730-1-josef@toxicpanda.com>

From: Josef Bacik
> Sent: 13 August 2020 15:53
> 
>   sysctl: pass kernel pointers to ->proc_handler
> 
> we have been pre-allocating a buffer to copy the data from the proc
> handlers into, and then copying that to userspace.  The problem is this
> just blind kmalloc()'s the buffer size passed in from the read, which in
> the case of our 'cat' binary was 64kib.  Order-4 allocations are not
> awesome, and since we can potentially allocate up to our maximum order,
> use vmalloc for these buffers.

What happens if I run 'dd bs=16M ...' ?

	David

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Registration No: 1397386 (Wales)


  parent reply	other threads:[~2020-08-13 16:19 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-13 14:53 Josef Bacik
2020-08-13 14:59 ` Matthew Wilcox
2020-08-13 15:08   ` Josef Bacik
2020-08-13 15:33 ` [PATCH][v2] " Josef Bacik
2020-08-13 15:37   ` Christoph Hellwig
2020-08-13 15:40     ` Josef Bacik
2020-08-13 15:41       ` Christoph Hellwig
2020-08-13 16:20         ` Al Viro
2020-08-13 17:19           ` Josef Bacik
2020-08-13 17:31             ` Al Viro
2020-08-13 17:36               ` Josef Bacik
2020-08-13 21:10             ` David Laight
2020-08-13 21:31               ` Josef Bacik
2020-08-13 16:19 ` David Laight [this message]
2020-08-13 16:21   ` [PATCH] " Al Viro
2020-08-13 17:08   ` Josef Bacik
2021-02-10 15:54 Josef Bacik
2021-02-10 17:16 ` Vlastimil Babka
2021-02-10 18:15 ` Matthew Wilcox

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