Messages in this thread | | | Date | Thu, 13 Nov 2008 04:44:25 +0100 | From | Nick Piggin <> | Subject | Re: [patch 2/8] x86 PAT: set VM_PFNMAP flag in vm_insert_pfn |
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On Wed, Nov 12, 2008 at 04:02:47PM -0800, Pallipadi, Venkatesh wrote: > > > >-----Original Message----- > >From: Nick Piggin [mailto:npiggin@suse.de] > >Sent: Wednesday, November 12, 2008 3:23 PM > >To: Pallipadi, Venkatesh > >Cc: Ingo Molnar; Thomas Gleixner; H.Peter Anvin; Hugh Dickins; > >Roland Dreier; Jesse Barnes; Jeremy Fitzhardinge; Arjan van de > >Ven; linux-kernel@vger.kernel.org; Siddha, Suresh B > >Subject: Re: [patch 2/8] x86 PAT: set VM_PFNMAP flag in vm_insert_pfn > > > >You have to be careful of this, because it can be called with mmap_sem > >held for read only. Hmm, I guess vm_insert_page is doing the > >same thing. > >Probably mostly works because all other modifiers of vm_flags > >are holding > >mmap_sem. > > Yes. I did the patch looking at vm_insert_page doing similar thing. > > > > >However, in some cases, code can do vm_insert_pfn and vm_insert_page > >(actually hmm, no vm_insert_mixed actually should cover most of those > >cases). > > > >Still, I'd be much happier if we could make these into BUG_ON, and then > >teach callers to set it in their .mmap routines. > > Actually, vm_insert_pfn() already has a BUG_ON() at the start for cases > where neither (or both) MIXEDMAP and PFNMAP is not set. So, that should > cover the case we are worried about it here and we can eliminate this > patch altogether. Only part I am not sure about is why we are looking > for MIXEDMAP here. Shouldn't they be using vm_insert_mixed instead?
They should, but it will do an inesrt_pfn in some cases, won't it?
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