Re: Linux-2.2.0 bad VM behaviour "dd if=/dev/zero of=/dev/hdc bs=256k"

Linus Torvalds (torvalds@transmeta.com)
Wed, 27 Jan 1999 13:34:37 -0800 (PST)


On Wed, 27 Jan 1999, Andrea Arcangeli wrote:
>
> My point is that I don't want more dirty buffers than the maximal number
> of write request that can be in fly by ll_rw_block(). So it looked to me
> that was the best thing to do... That way I am pretty sure that I'll be
> able to alloc memory without any kind of harm. Otherwise I get a fixed
> amount of buffers unfreeable because dirty, until the process that is
> using the block device stops.

So what makes block devices so special?

_I_ think that block devices are the _last_ thing you should do this for.
A normal user doesn't have access to a block device, so it cannot be
exploited by normal users being nasty anyway.

In short, this looks like special-casing a generic problem, and choosing
the wrong special case at that.

Linus

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