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

[Sergey Senozhatsky]

On (06/16/16 10:58), Michal Hocko wrote:
> > [..]
> > [  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)
> [...]

I think it is

1248 void page_add_new_anon_rmap(struct page *page,
1249         struct vm_area_struct *vma, unsigned long address, bool compound)
1250 {
1251         int nr = compound ? hpage_nr_pages(page) : 1;
1252
1253         VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
1254         __SetPageSwapBacked(page);

> > [  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.

collapse_huge_page() ->mmap_sem fixup patch (http://marc.info/?l=linux-mm&m=146495692807404&w=2)
is in next-20160615. or do you mean some other patch?

	-ss