Re: [PATCH] zsmalloc: calling zs_map_object() from irq is a bug

From	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] zsmalloc: calling zs_map_object() from irq is a bug
Date	2017-09-28 02:50 +0200
Message-ID	<uuvbz-1NM-3@gated-at.bofh.it> (permalink)
References	<urGPU-7L3-17@gated-at.bofh.it> <urGZz-7Og-1@gated-at.bofh.it> <uu8oG-3pD-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On (09/26/17 17:26), Andrew Morton 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?

ah, OK. will follow up.

	-ss

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Re: [PATCH] zsmalloc: calling zs_map_object() from irq is a bug Andrew Morton <akpm@linux-foundation.org> - 2017-09-27 02:30 +0200
  Re: [PATCH] zsmalloc: calling zs_map_object() from irq is a bug Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-09-28 02:50 +0200

csiph-web