Re: [PATCH v2 3/3] mm: Protect kernel pgtables in apply_to_pte_range()

[Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>]

On Thu, 10 Apr 2025 16:50:33 +0200 Alexander Gordeev <agordeev@xxxxxxxxxxxxx> 
wrote:

> On Tue, Apr 08, 2025 at 06:07:32PM +0200, Alexander Gordeev wrote:
> 
> Hi Andrew,
> 
> > The lazy MMU mode can only be entered and left under the protection
> > of the page table locks for all page tables which may be modified.
> 
> Heiko Carstens noticed that the above claim is not valid, since
> v6.15-rc1 commit 691ee97e1a9d ("mm: fix lazy mmu docs and usage"),
> which restates it to:
> 
> "In the general case, no lock is guaranteed to be held between entry and exit
> of the lazy mode. So the implementation must assume preemption may be enabled"
> 
> That effectively invalidates this patch, so it needs to be dropped.
> 
> Patch 2 still could be fine, except -stable and Fixes tags and it does
> not need to aim 6.15-rcX. Do you want me to repost it?

I dropped the whole series - let's start again.