From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f69.google.com (mail-it0-f69.google.com [209.85.214.69]) by kanga.kvack.org (Postfix) with ESMTP id 027B06B0038 for ; Wed, 16 Nov 2016 05:51:31 -0500 (EST) Received: by mail-it0-f69.google.com with SMTP id g187so40509929itc.2 for ; Wed, 16 Nov 2016 02:51:30 -0800 (PST) Received: from merlin.infradead.org (merlin.infradead.org. [2001:4978:20e::2]) by mx.google.com with ESMTPS id o131si1813702itd.23.2016.11.16.02.51.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Nov 2016 02:51:30 -0800 (PST) Date: Wed, 16 Nov 2016 11:51:32 +0100 From: Peter Zijlstra Subject: Re: [PATCH 01/21] mm: Join struct fault_env and vm_fault Message-ID: <20161116105132.GR3142@twins.programming.kicks-ass.net> References: <1478233517-3571-1-git-send-email-jack@suse.cz> <1478233517-3571-2-git-send-email-jack@suse.cz> <20161115215021.GA23021@node> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161115215021.GA23021@node> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Jan Kara , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@ml01.01.org, Andrew Morton , Ross Zwisler , "Kirill A. Shutemov" On Wed, Nov 16, 2016 at 12:50:21AM +0300, Kirill A. Shutemov wrote: > On Fri, Nov 04, 2016 at 05:24:57AM +0100, Jan Kara wrote: > > Currently we have two different structures for passing fault information > > around - struct vm_fault and struct fault_env. DAX will need more > > information in struct vm_fault to handle its faults so the content of > > that structure would become event closer to fault_env. Furthermore it > > would need to generate struct fault_env to be able to call some of the > > generic functions. So at this point I don't think there's much use in > > keeping these two structures separate. Just embed into struct vm_fault > > all that is needed to use it for both purposes. > > > > Signed-off-by: Jan Kara > > I'm not necessary dislike this, but I remember Peter had objections before > when I proposed something similar. > > Peter? My objection was that it would be a layering violation. The 'filesystem' shouldn't know about page-tables, all it should do is return a page matching a specific offset. So fault_env manages the core vm parts and has the page-table bits in, vm_fault manages the filesystem interface and gets us a page given an offset. Now, I'm entirely out of touch wrt DAX, so I've not idea what that needs/wants. > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index a92c8d73aeaf..657eb69eb87e 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -292,10 +292,16 @@ extern pgprot_t protection_map[16]; > > * pgoff should be used in favour of virtual_address, if possible. > > */ > > struct vm_fault { > > + struct vm_area_struct *vma; /* Target VMA */ > > unsigned int flags; /* FAULT_FLAG_xxx flags */ > > gfp_t gfp_mask; /* gfp mask to be used for allocations */ > > pgoff_t pgoff; /* Logical page offset based on vma */ > > + unsigned long address; /* Faulting virtual address */ > > + void __user *virtual_address; /* Faulting virtual address masked by > > + * PAGE_MASK */ > > + pmd_t *pmd; /* Pointer to pmd entry matching > > + * the 'address' > > + */ > > > > struct page *cow_page; /* Handler may choose to COW */ > > struct page *page; /* ->fault handlers should return a Egads, horrific commenting style that :-) -- 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