linux-kernel - Re: [PATCH v6 14/14] mm: Add basic tests for lazy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <6afcb722-80cc-4bb2-a745-d9ad7893f0ae@arm.com>
Date: Wed, 17 Dec 2025 16:37:32 +0100
From: Kevin Brodsky <kevin.brodsky@....com>
To: Ryan Roberts <ryan.roberts@....com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Alexander Gordeev <agordeev@...ux.ibm.com>,
 Andreas Larsson <andreas@...sler.com>,
 Anshuman Khandual <anshuman.khandual@....com>,
 Boris Ostrovsky <boris.ostrovsky@...cle.com>, Borislav Petkov
 <bp@...en8.de>, Catalin Marinas <catalin.marinas@....com>,
 Christophe Leroy <christophe.leroy@...roup.eu>,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 David Hildenbrand <david@...hat.com>, "David S. Miller"
 <davem@...emloft.net>, David Woodhouse <dwmw2@...radead.org>,
 "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
 Jann Horn <jannh@...gle.com>, Juergen Gross <jgross@...e.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>, Michal Hocko <mhocko@...e.com>,
 Mike Rapoport <rppt@...nel.org>, Nicholas Piggin <npiggin@...il.com>,
 Peter Zijlstra <peterz@...radead.org>,
 "Ritesh Harjani (IBM)" <ritesh.list@...il.com>,
 Suren Baghdasaryan <surenb@...gle.com>, Thomas Gleixner
 <tglx@...utronix.de>, Venkat Rao Bagalkote <venkat88@...ux.ibm.com>,
 Vlastimil Babka <vbabka@...e.cz>, Will Deacon <will@...nel.org>,
 Yeoreum Yun <yeoreum.yun@....com>, linux-arm-kernel@...ts.infradead.org,
 linuxppc-dev@...ts.ozlabs.org, sparclinux@...r.kernel.org,
 xen-devel@...ts.xenproject.org, x86@...nel.org
Subject: Re: [PATCH v6 14/14] mm: Add basic tests for lazy_mmu

On 17/12/2025 11:01, Ryan Roberts wrote:
> On 17/12/2025 09:26, Kevin Brodsky wrote:
>> On 17/12/2025 05:14, Andrew Morton wrote:
>>> On Mon, 15 Dec 2025 15:03:23 +0000 Kevin Brodsky <kevin.brodsky@....com> wrote:
>>>
>>>> Add basic KUnit tests for the generic aspects of the lazy MMU mode:
>>>> ensure that it appears active when it should, depending on how
>>>> enable/disable and pause/resume pairs are nested.
>>> I needed this for powerpc allmodconfig;
>>>
>>> --- a/arch/powerpc/mm/book3s64/hash_tlb.c~mm-add-basic-tests-for-lazy_mmu-fix
>>> +++ a/arch/powerpc/mm/book3s64/hash_tlb.c
>>> @@ -30,6 +30,7 @@
>>>  #include <trace/events/thp.h>
>>>  
>>>  DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch);
>>> +EXPORT_SYMBOL_GPL(ppc64_tlb_batch);
>>>  
>>>  /*
>>>   * A linux PTE was changed and the corresponding hash table entry
>>> @@ -154,6 +155,7 @@ void __flush_tlb_pending(struct ppc64_tl
>>>  		flush_hash_range(i, local);
>>>  	batch->index = 0;
>>>  }
>>> +EXPORT_SYMBOL_GPL(__flush_tlb_pending);
>>>  
>>>  void hash__tlb_flush(struct mmu_gather *tlb)
>>>  {
>>> _
>> Oh indeed I hadn't considered that arch_{enter,leave}_lazy_mmu_mode()
>> refer to those symbols on powerpc... Maybe a bit overkill to export
>> those just for a test module, but I'm not sure there's a good
>> alternative. Forcing LAZY_MMU_MODE_KUNIT_TEST=y is ugly as it would also
>> force KUNIT=y. Alternatively we could depend on !PPC, not pretty either.
> Does EXPORT_SYMBOL_IF_KUNIT() help?

It most certainly would, I didn't know about that one, thanks!

- Kevin