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Re: [PATCH v2 0/7] Nesting support for lazy MMU mode
- To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Kevin Brodsky <kevin.brodsky@xxxxxxx>
- From: David Hildenbrand <david@xxxxxxxxxx>
- Date: Tue, 9 Sep 2025 11:21:54 +0200
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- Cc: linux-mm@xxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, Alexander Gordeev <agordeev@xxxxxxxxxxxxx>, Andreas Larsson <andreas@xxxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Catalin Marinas <catalin.marinas@xxxxxxx>, Christophe Leroy <christophe.leroy@xxxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, "David S. Miller" <davem@xxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Jann Horn <jannh@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>, Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>, Madhavan Srinivasan <maddy@xxxxxxxxxxxxx>, Michael Ellerman <mpe@xxxxxxxxxxxxxx>, Michal Hocko <mhocko@xxxxxxxx>, Mike Rapoport <rppt@xxxxxxxxxx>, Nicholas Piggin <npiggin@xxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Ryan Roberts <ryan.roberts@xxxxxxx>, Suren Baghdasaryan <surenb@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Vlastimil Babka <vbabka@xxxxxxx>, Will Deacon <will@xxxxxxxxxx>, Yeoreum Yun <yeoreum.yun@xxxxxxx>, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, linuxppc-dev@xxxxxxxxxxxxxxxx, sparclinux@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 09 Sep 2025 09:22:15 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 09.09.25 04:16, Andrew Morton wrote:
On Mon, 8 Sep 2025 08:39:24 +0100 Kevin Brodsky <kevin.brodsky@xxxxxxx> wrote:
The main change enabling nesting is patch 2, following the approach
suggested by Catalin Marinas [4]: have enter() return some state and
the matching leave() take that state.
This is so totally the correct way. Thanks.
Staring at this, I wonder if we could alternatively handle it like
pagefault_disable()/pagefault_enable(), having something like
current->lazy_mmu_enabled.
We wouldn't have to worry about preemption in that case I guess (unless
the arch has special requirements).
Not sure if that was already discussed, just a thought.
--
Cheers
David / dhildenb
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