From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx151.postini.com [74.125.245.151]) by kanga.kvack.org (Postfix) with SMTP id D6E876B002B for ; Wed, 10 Oct 2012 00:06:36 -0400 (EDT) Message-ID: <1349841989.2759.317.camel@ul30vt.home> Subject: Re: [PATCH v3 10/10] mm: kill vma flag VM_RESERVED and mm->reserved_vm counter From: Alex Williamson Date: Tue, 09 Oct 2012 22:06:29 -0600 In-Reply-To: <1349823616.2759.308.camel@ul30vt.home> References: <20120731103724.20515.60334.stgit@zurg> <20120731104239.20515.702.stgit@zurg> <1349776921.21172.4091.camel@edumazet-glaptop> <1349792507.2759.283.camel@ul30vt.home> <1349823616.2759.308.camel@ul30vt.home> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Eric Dumazet , Konstantin Khlebnikov , linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Hugh Dickins , Nick Piggin On Tue, 2012-10-09 at 17:00 -0600, Alex Williamson wrote: > On Tue, 2012-10-09 at 08:21 -0600, Alex Williamson wrote: > > On Tue, 2012-10-09 at 21:12 +0900, Linus Torvalds wrote: > > > On Tue, Oct 9, 2012 at 7:02 PM, Eric Dumazet wrote: > > > > > > > > It seems drivers/vfio/pci/vfio_pci.c uses VM_RESERVED > > > > > > Yeah, I just pushed out what I think is the right (trivial) fix. > > > > Thank you, looks correct to me as well. > > Well, that might still be correct, but it's actually b3b9c293 (mm, x86, > pat: rework linear pfn-mmap tracking) that breaks vfio. As soon as I > add that commit our use of mmap'd device areas stops working, both > mapping them through the iommu and through kvm. kvm hits the BUG_ON > from !kvm_is_mmio_pfn in virt/kvm/kvm_main.c:hva_to_pfn. Thanks, It looks like vfio was for some reason relying on the cow special case in remap_pfn_range() to set vma->vm_pgoff. Since we're not doing a is_cow_mapping, vm_pgoff is no longer updated in that function after b3b9c293. I'll add a vfio patch to fix this. Thanks, Alex -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org