x86 warnings in arch/x86/mm/pageattr.c:560

x86 warnings in arch/x86/mm/pageattr.c:560

[Nick Piggin]

Hi,

I've been getting this warning intermittently since the merge window
opened. Considering that track_pfn_vma_new is called before the ptes
are set up in remap_pfn_range (and remap_pfn_range contains a warning
if the ptes *are* nonzero), I don't know how this is supposed to work?

Anyway, I can of course test patches.

------------[ cut here ]------------
WARNING: at arch/x86/mm/pageattr.c:560 __change_page_attr_set_clr+0x9ef/0xa00()
Hardware name: empty
CPA: called for zero pte. vaddr = ffff8800cff4e000 cpa->vaddr = ffff8800cff4e000
Modules linked in:
Pid: 2311, comm: mcelog Not tainted 2.6.29-rc2-00013-gf3b8436 #75
Call Trace:
 [<ffffffff8024053a>] warn_slowpath+0xea/0x160
 [<ffffffff803ab692>] mix_pool_bytes_extract+0x52/0x160
 [<ffffffff803abc63>] extract_buf+0x83/0xf0
 [<ffffffff8028c65d>] zone_statistics+0x7d/0x80
 [<ffffffff80280686>] get_page_from_freelist+0x4b6/0x690
 [<ffffffff80280a57>] __alloc_pages_internal+0xe7/0x4d0
 [<ffffffff8022e9ff>] __change_page_attr_set_clr+0x9ef/0xa00
 [<ffffffff8029bad4>] __purge_vmap_area_lazy+0x104/0x180
 [<ffffffff8029d3ce>] vm_unmap_aliases+0x17e/0x190
 [<ffffffff8022eaea>] change_page_attr_set_clr+0xda/0x380
 [<ffffffff8022eeed>] _set_memory_wb+0x1d/0x30
 [<ffffffff802305a6>] reserve_pfn_range+0x126/0x300
 [<ffffffff8022eaea>] change_page_attr_set_clr+0xda/0x380
 [<ffffffff80292510>] remap_pfn_range+0xa0/0x3d0
 [<ffffffff80230c33>] phys_mem_access_prot_allowed+0xf3/0x1e0
 [<ffffffff8028be48>] vma_prio_tree_insert+0x28/0x110
 [<ffffffff803ab1f6>] mmap_mem+0x96/0xc0
 [<ffffffff80297887>] mmap_region+0x247/0x670
 [<ffffffff80297f94>] do_mmap_pgoff+0x2e4/0x3f0
 [<ffffffff80210905>] sys_mmap+0x115/0x140
 [<ffffffff8020b91b>] system_call_fastpath+0x16/0x1b
---[ end trace 488160a0a7b56966 ]---
mcelog:2311 reserve_pfn_range ioremap_change_attr failed write-back for cff4e000-cff50000

Re: x86 warnings in arch/x86/mm/pageattr.c:560

[Ingo Molnar]

* Nick Piggin <npiggin@suse.de> wrote:

> Hi,
> 
> I've been getting this warning intermittently since the merge window
> opened. Considering that track_pfn_vma_new is called before the ptes
> are set up in remap_pfn_range (and remap_pfn_range contains a warning
> if the ptes *are* nonzero), I don't know how this is supposed to work?
> 
> Anyway, I can of course test patches.
> 
> ------------[ cut here ]------------
> WARNING: at arch/x86/mm/pageattr.c:560 __change_page_attr_set_clr+0x9ef/0xa00()
> Hardware name: empty
> CPA: called for zero pte. vaddr = ffff8800cff4e000 cpa->vaddr = ffff8800cff4e000

Ok, i have just queued up a fix that could address this - could you please 
try latest tip/master:

   http://people.redhat.com/mingo/tip.git/README

does it still produce that warning?

	Ingo