linux-kernel - Re: Top 10 bugs/warnings for the week of March 23rd, 2008

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Message-ID: <20080526162048.GH32407@duck.suse.cz>
Date:	Mon, 26 May 2008 18:20:48 +0200
From:	Jan Kara <jack@...e.cz>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Theodore Tso <tytso@....edu>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Greg KH <greg@...ah.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: Top 10 bugs/warnings for the week of March 23rd, 2008

On Mon 26-05-08 12:48:32, Ingo Molnar wrote:
> 
> * Theodore Tso <tytso@....EDU> wrote:
> 
> > On Mon, May 26, 2008 at 11:39:13AM +0200, Ingo Molnar wrote:
> > > Exactly why is pulling an USB stick considered "stupid"? Last i checked 
> > > there was no physical lock preventing users from doing that.
> > > 
> > > Sure, pulling a mounted USB stick is inconvenient ... for _us_ 
> > > kernel developers. But the user really doesnt care and shouldnt 
> > > care.
> > 
> > Because they could lose data?  Because if the kernel wakes up and 
> > tries writing to the USB stick right as they pull it out, it could 
> > physically damage the flash format?  I know, stupid reason...  :-)
> 
> user can lose data in many other ways, that's not the issue - the issue 
> here is something very crutial: the kernel gets confused about a _very_ 
> common user-triggerable condition.
> 
> That confusion must not happen in a modern OS and the kernel should be 
> resilient and cope with such external events. And we must not 
> deprioritize it with an incorrect "user did something stupid" tag... 
> That argument might have been valid 15 years ago when floppies could be 
> locked and you needed a needle to force-eject it but it is rather lame 
> today when unplugging an USB stick is as easy as moving the mouse.
> 
> If there's something stupid here it's the kernel not dealing with that 
> condition properly. Yes, the "user action" here looks "trivial" to the 
> user but what happens below is indeed very hard technically, but who 
> said that writing an OS from scratch would be an easy task? ;-)
  Well, Ingo, I don't know if you've noticed but the machine continues to run
just fine, as far as I understand. It only spits a dangerously looking
warning and that's it. I agree we shouldn't be doing this but I don't really
find this a critical problem.

									Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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