linux-kernel - BUG_ON when zsmalloc from IRQ (was zram: fix null dereference of handle)

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Message-ID: <20170919103825.GD401@jagdpanzerIV.localdomain>
Date:   Tue, 19 Sep 2017 19:38:25 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, kernel-team <kernel-team@....com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: BUG_ON when zsmalloc from IRQ (was zram: fix null dereference of
 handle)

ah... this should have had another Subject line....
sorry.

	-ss

On (09/19/17 19:21), Sergey Senozhatsky wrote:
> Minchan,
> 
> I just ran across it [because I had a bug to analize where this
> part was involved]. I'd really prefer the kernel to BUG_ON immediately
> instead of dying in agony.
> 
> can we, please, return BUG_ON() back?
> 
> there is no point in trying to save the kernel once it did that type
> of violation.
> 
> ---
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 7c38e850a8fc..685049a9048d 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1349,7 +1349,7 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle,
>          * pools/users, we can't allow mapping in interrupt context
>          * because it can corrupt another users mappings.
>          */
> -       WARN_ON_ONCE(in_interrupt());
> +       BUG_ON(in_interrupt());
>  
>         /* From now on, migration cannot move the object */
>         pin_tag(handle);
>