From: Andrew Morton <akpm@linux-foundation.org>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [PATCH] zsmalloc: calling zs_map_object() from irq is a bug
Date: Tue, 26 Sep 2017 17:26:32 -0700 [thread overview]
Message-ID: <20170926172632.cf302deff749d12f74d8a4da@linux-foundation.org> (raw)
In-Reply-To: <20170920064739.GA11000@bbox>
On Wed, 20 Sep 2017 15:47:39 +0900 Minchan Kim <minchan@kernel.org> wrote:
> On Wed, Sep 20, 2017 at 03:39:41PM +0900, Sergey Senozhatsky wrote:
> > Use BUG_ON(in_interrupt()) in zs_map_object(). Calling this
> > function from IRQ is a bug, because we use per-CPU mappings
> > and interrupt may corrupt those buffers.
> >
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
>
> IMHO, corruption the buffer would be not enough to be a BUG_ON
> which stop the system fully so user loses any chances to shut
> down smooth/hunt it down.
>
> More serious thing of our case is that it can leak other user's
> data by overwriting, which is more concern I am thinking now.
>
In an off-list email Linus has basically stated that all new uses of
BUG_ON should include words in the changelog or code comments
explaining why it is justifiable to kill the machine when the condition
triggers.
So can we please have a v2 with the appropriate comment?
next prev parent reply other threads:[~2017-09-27 0:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-20 6:39 Sergey Senozhatsky
2017-09-20 6:47 ` Minchan Kim
2017-09-20 6:48 ` Sergey Senozhatsky
2017-09-27 0:26 ` Andrew Morton [this message]
2017-09-28 0:41 ` Sergey Senozhatsky
2017-09-29 4:51 Sergey Senozhatsky
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