linux-kernel - Re: [PATCH] zsmalloc: calling zs_map

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Message-ID: <20170920064739.GA11000@bbox>
Date:   Wed, 20 Sep 2017 15:47:39 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCH] zsmalloc: calling zs_map_object() from irq is a bug

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@...il.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.

So,

Acked-by: Minchan Kim <minchan@...nel.org>

Thanks!