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b=etonnWNrXoT73baz3xJtEhRpNWkjVDs2f5l711wzJlSi2+mJFHLC74fsobQFx/gdL DKN/pu+iXg2MuJxCGaKiT3VVrOIlPbIqnRB/d6bIMZr+A7/iXoEhdVldUQ8v3J1lAt mp4QGN9mzmGajX3Nvi3yu2h20lnjJpMuBOhXKQhyp18GbkTf/is9Q/5QP+tU/Q7ETd MUkamoN2reB0VRMt+53H6OWapmNio02uzoluNZN8ie+pcu7Zaqjtnh3tzUFlSXc7Xw QZ+Bu0jZ3jHHt8IERYRTC7K94xQ/w9P6ZakjlcZHCsPcTytYxaDoBcJx7HZOvUQ54T LNpTnfRFsRaQg== Date: Wed, 2 Sep 2026 17:21:51 +0100 From: "Lorenzo Stoakes (ARM)" To: Andi Kleen Cc: Pedro Falcato , Andi Kleen , akpm@linux-foundation.org, liam@infradead.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] RCU safety for vma maple tree walks Message-ID: References: <20260831143511.1133029-1-ak@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: 55zpww6w3yitckpcwk341iaiatnrmgj9 X-Rspamd-Queue-Id: 30E79C0008 X-HE-Tag: 1788366117-946114 X-HE-Meta: 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 sUDW/VLt 2tqe41c7n2uAwbUAmgoD3djoJUXqkhqJFcUr+mmw/TFuwlTLXi+leKTgieaKbzIdnyGa89r+O3tpo6G2IMB7dbjDq9cqamUILrpmB2bfbEoy6hk0iBbMkA3v8IIuh6Mdqcx2ZrQzuwdo9SnEGYXYjGS0gUYXX1Ke53KcR03SqMd4M+ewTBX8r752mzNU6oKEK/8uleDOJREiu57YQQJMKjPTmC0eqdQzMPpkE7/wN45i2iFvpLV8qSrTM2QM98gDyMQgV1d0E2UsE8vZPoiwF1HOn8TIyh7jN5WJTpuCIp46ihHk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Andi, Looking at https://lore.kernel.org/lkml/20260831150651.1134594-6-ak@kernel.org/ I can see the cause of your issue - it's your own patch, exactly as we've been telling you. You're inserting a VMA on a uprobe_mmap() call, which is completely incorrect: -> vma_complete() -> uprobe_mmap(vp->insert) -> install_breakpoint() -> ... -> create_uprobe_ptwrite_page() -> _install_special_mapping() Now you're inserting a VMA, using an entirely distinct iterator, while an existing VMA iterator is in use. That means you can end up rebalancing the tree and _trashing the iterator_ in the core mm code. Your (LLM's) proposed solution to this was to keep on doing the completely broken thing, but by inserting various RCU locks, preventing a KASAN report on use-after-free's due to avoiding an RCU grace period expiring. You can't reproduce this upstream, because the bug is in your (RFC) series. So, exactly as we've been trying to tell you. > Assisted-by: omp:gpt-5.6-luna I'm a little grumpy about this as you've taken up a bunch of our time to assess two sets of completely broken LLM-generated code, and you've mostly responded by denying what the authors of this code have repeatedly told you. You also seem to be using one of the lightest weight LLM models - it isn't a great choice for core kernel work, especially in areas you are unfamiliar with. In future, please audit the code and make sure you understand every part of it as per https://docs.kernel.org/process/generated-content.html As with the output of any tooling, the result may be incorrect or inappropriate. You are expected to understand and to be able to defend everything you submit. If you are unable to do so, then do not submit the resulting changes. Please respect our time moving forwards, thanks. -- Cheers, Lorenzo