linux-kernel - Re: [RFC PATCH] mm/rmap: do not call mmu_notifier_invalidate

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Message-ID: <20170829191449.GE7546@redhat.com>
Date:   Tue, 29 Aug 2017 15:14:49 -0400
From:   Jerome Glisse <jglisse@...hat.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>, Bernhard Held <berny156@....de>,
        Adam Borowski <kilobyte@...band.pl>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Takashi Iwai <tiwai@...e.de>,
        Nadav Amit <nadav.amit@...il.com>,
        Mike Galbraith <efault@....de>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        axie <axie@....com>, Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC PATCH] mm/rmap: do not call mmu_notifier_invalidate_page()
 v3

On Tue, Aug 29, 2017 at 12:09:45PM -0700, Linus Torvalds wrote:
> On Tue, Aug 29, 2017 at 12:05 PM, Jérôme Glisse <jglisse@...hat.com> wrote:
> > Some MMU notifier need to be able to sleep during callback. This was
> > broken by c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use
> > page_vma_mapped_walk()").
> 
> No. No no no.
> 
> Didn't you learn *anything* from the bug?
> 
> You cannot replace "mmu_notifier_invalidate_page()" with
> "mmu_notifier_invalidate_range()".
> 
> KVM implements mmu_notifier_invalidate_page().
> 
> IT DOES NOT IMPLEMENT THAT RANGE CRAP AT ALL.
> 
> So any approach like this is fundamentally garbage. Really. Stop
> sending crap. This is exactly tehe same thing that we already reverted
> because it was broken shit. Why do you re-send it without actually
> fixing the fundamental problems that were pointed out?
> 

Sorry i missed the kvm not implementing the range() only callback so
i am gonna respin with start/end.

Jérôme