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From: Dave Hansen <dave.hansen@intel.com>
To: Bo Li <libo.gcs85@bytedance.com>,
	tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	dave.hansen@linux.intel.com, x86@kernel.org, luto@kernel.org,
	kees@kernel.org, akpm@linux-foundation.org, david@redhat.com,
	juri.lelli@redhat.com, vincent.guittot@linaro.org,
	peterz@infradead.org
Cc: dietmar.eggemann@arm.com, hpa@zytor.com, acme@kernel.org,
	namhyung@kernel.org, mark.rutland@arm.com,
	alexander.shishkin@linux.intel.com, jolsa@kernel.org,
	irogers@google.com, adrian.hunter@intel.com,
	kan.liang@linux.intel.com, viro@zeniv.linux.org.uk,
	brauner@kernel.org, jack@suse.cz, lorenzo.stoakes@oracle.com,
	Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org,
	surenb@google.com, mhocko@suse.com, rostedt@goodmis.org,
	bsegall@google.com, mgorman@suse.de, vschneid@redhat.com,
	jannh@google.com, pfalcato@suse.de, riel@surriel.com,
	harry.yoo@oracle.com, linux-kernel@vger.kernel.org,
	linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, duanxiongchun@bytedance.com,
	yinhongbo@bytedance.com, dengliang.1214@bytedance.com,
	xieyongji@bytedance.com, chaiwen.cc@bytedance.com,
	songmuchun@bytedance.com, yuanzhu@bytedance.com,
	chengguozhu@bytedance.com, sunjiadong.lff@bytedance.com
Subject: Re: [RFC v2 14/35] RPAL: enable page fault handling
Date: Fri, 30 May 2025 06:59:29 -0700	[thread overview]
Message-ID: <304ea078-0f09-43d6-9dd2-264eb195e33e@intel.com> (raw)
In-Reply-To: <a7c183833cca723238d4173a6df771dd7e340762.1748594840.git.libo.gcs85@bytedance.com>

On 5/30/25 02:27, Bo Li wrote:
>  arch/x86/mm/fault.c     | 271 ++++++++++++++++++++++++++++++++++++++++
>  arch/x86/rpal/mm.c      |  34 +++++
>  arch/x86/rpal/service.c |  24 ++++
>  arch/x86/rpal/thread.c  |  23 ++++
>  include/linux/rpal.h    |  81 ++++++++----
>  5 files changed, 412 insertions(+), 21 deletions(-)

I'm actually impressed again that you've managed to get this ported over
to a newer kernel _and_ broken it up.

But just taking a quick peek at _one_ patch, this is far, far below the
standards by which we do kernel development. This appears to have simply
copied chunks of existing code, hacked it to work with "RPAL" and then
#ifdef'd.

This is, unfortunately, copying and pasting at its worst. It creates
dual paths that inevitably bit rot in some way and are hard to maintain.

So, just to be clear: it's a full an unequivocal NAK from me on this
series. This introduces massive change, massive security risk, can't
possibly be backward compatible, has no users (well, maybe one) and the
series is not put together in anything remotely resembling how we like
to do kernel development.

I'd appreciate if you could not cc me on future versions if you choose
to go forward with this. But I urge you to stop now.


  reply	other threads:[~2025-05-30 13:59 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-30  9:27 [RFC v2 00/35] optimize cost of inter-process communication Bo Li
2025-05-30  9:27 ` [RFC v2 01/35] Kbuild: rpal support Bo Li
2025-05-30  9:27 ` [RFC v2 02/35] RPAL: add struct rpal_service Bo Li
2025-05-30  9:27 ` [RFC v2 03/35] RPAL: add service registration interface Bo Li
2025-05-30  9:27 ` [RFC v2 04/35] RPAL: add member to task_struct and mm_struct Bo Li
2025-05-30  9:27 ` [RFC v2 05/35] RPAL: enable virtual address space partitions Bo Li
2025-05-30  9:27 ` [RFC v2 06/35] RPAL: add user interface Bo Li
2025-05-30  9:27 ` [RFC v2 07/35] RPAL: enable shared page mmap Bo Li
2025-05-30  9:27 ` [RFC v2 08/35] RPAL: enable sender/receiver registration Bo Li
2025-05-30  9:27 ` [RFC v2 09/35] RPAL: enable address space sharing Bo Li
2025-05-30  9:27 ` [RFC v2 10/35] RPAL: allow service enable/disable Bo Li
2025-05-30  9:27 ` [RFC v2 11/35] RPAL: add service request/release Bo Li
2025-05-30  9:27 ` [RFC v2 12/35] RPAL: enable service disable notification Bo Li
2025-05-30  9:27 ` [RFC v2 13/35] RPAL: add tlb flushing support Bo Li
2025-05-30  9:27 ` [RFC v2 14/35] RPAL: enable page fault handling Bo Li
2025-05-30 13:59   ` Dave Hansen [this message]
2025-05-30  9:27 ` [RFC v2 15/35] RPAL: add sender/receiver state Bo Li
2025-05-30  9:27 ` [RFC v2 16/35] RPAL: add cpu lock interface Bo Li
2025-05-30  9:27 ` [RFC v2 17/35] RPAL: add a mapping between fsbase and tasks Bo Li
2025-05-30  9:27 ` [RFC v2 18/35] sched: pick a specified task Bo Li
2025-05-30  9:27 ` [RFC v2 19/35] RPAL: add lazy switch main logic Bo Li
2025-05-30  9:27 ` [RFC v2 20/35] RPAL: add rpal_ret_from_lazy_switch Bo Li
2025-05-30  9:27 ` [RFC v2 21/35] RPAL: add kernel entry handling for lazy switch Bo Li
2025-05-30  9:27 ` [RFC v2 22/35] RPAL: rebuild receiver state Bo Li
2025-05-30  9:27 ` [RFC v2 23/35] RPAL: resume cpumask when fork Bo Li
2025-05-30  9:27 ` [RFC v2 24/35] RPAL: critical section optimization Bo Li
2025-05-30  9:27 ` [RFC v2 25/35] RPAL: add MPK initialization and interface Bo Li
2025-05-30  9:27 ` [RFC v2 26/35] RPAL: enable MPK support Bo Li
2025-05-30 17:03   ` Dave Hansen
2025-05-30  9:27 ` [RFC v2 27/35] RPAL: add epoll support Bo Li
2025-05-30  9:27 ` [RFC v2 28/35] RPAL: add rpal_uds_fdmap() support Bo Li
2025-05-30  9:27 ` [RFC v2 29/35] RPAL: fix race condition in pkru update Bo Li
2025-05-30  9:27 ` [RFC v2 30/35] RPAL: fix pkru setup when fork Bo Li
2025-05-30  9:27 ` [RFC v2 31/35] RPAL: add receiver waker Bo Li
2025-05-30  9:28 ` [RFC v2 32/35] RPAL: fix unknown nmi on AMD CPU Bo Li
2025-05-30  9:28 ` [RFC v2 33/35] RPAL: enable time slice correction Bo Li
2025-05-30  9:28 ` [RFC v2 34/35] RPAL: enable fast epoll wait Bo Li
2025-05-30  9:28 ` [RFC v2 35/35] samples/rpal: add RPAL samples Bo Li
2025-05-30  9:33 ` [RFC v2 00/35] optimize cost of inter-process communication Lorenzo Stoakes
2025-06-03  8:22   ` Bo Li
2025-06-03  9:22     ` Lorenzo Stoakes
2025-05-30  9:41 ` Pedro Falcato
2025-05-30  9:56 ` David Hildenbrand
2025-05-30 22:42 ` Andrew Morton
2025-05-31  7:16 ` Ingo Molnar
2025-06-03 17:49 ` H. Peter Anvin

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