linux-kernel - Re: [next-20160615] kernel BUG at mm/rmap.c:1251!

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Date:	Thu, 16 Jun 2016 10:58:37 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Vlastimil Babka <vbabka@...e.cz>,
	Minchan Kim <minchan@...nel.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [next-20160615] kernel BUG at mm/rmap.c:1251!

On Thu 16-06-16 17:46:57, Sergey Senozhatsky wrote:
> Hello,
> 
> [..]
> [  272.687656] vma ffff8800b855a5a0 start 00007f3576d58000 end 00007f3576f66000
>                next ffff8800b977d2c0 prev ffff8800bdfb1860 mm ffff8801315ff200
>                prot 8000000000000025 anon_vma ffff8800b7e583b0 vm_ops           (null)
>                pgoff 7f3576d58 file           (null) private_data           (null)
>                flags: 0x100073(read|write|mayread|maywrite|mayexec|account)
> [  272.691793] ------------[ cut here ]------------
> [  272.692820] kernel BUG at mm/rmap.c:1251!

Is this?
page_add_new_anon_rmap:
	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma)
[...]
> [  272.727842] BUG: sleeping function called from invalid context at include/linux/sched.h:2960

If yes then I am not sure we can do much about the this part. BUG_ON in
an atomic context is unfortunate but the BUG_ON points out a real bug so
we shouldn't drop it because of the potential atomic context. The above
VM_BUG_ON should definitely be addressed. I thought that Vlastimil has
pointed out some issues with the khugepaged lock inconsistencies which
might lead to issues like this.
-- 
Michal Hocko
SUSE Labs