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Wed, 01 Apr 2026 07:33:52 -0700 (PDT) Message-ID: <41b94c57-41e9-4273-8a58-3bf6498dde18@kernel.dk> Date: Wed, 1 Apr 2026 08:33:51 -0600 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] io_uring: protect remaining lockless ctx->rings accesses with RCU To: junxi qian , io-uring@vger.kernel.org Cc: lkp@intel.com References: <2915e619-06ec-414b-9458-92745c76e6f1@kernel.dk> Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/31/26 11:24 PM, junxi qian wrote: > Hi Jens, > > The kernel test robot reported sparse warnings on your commit (9d0a7bda72c5): > > io_uring/wait.c:309:49: sparse: cast removes address space '__rcu' of expression > io_uring/wait.c:319:16: sparse: cast removes address space '__rcu' of expression > io_uring/wait.c:319:54: sparse: cast removes address space '__rcu' of expression > > The issue is that wait.c lines 309 and 319 access ctx->rings_rcu directly > without going through rcu_dereference(), which sparse flags as an __rcu > address space violation. > > The fix would be to replace the raw ctx->rings_rcu dereferences with > io_get_rings(ctx), e.g.: > > READ_ONCE(ctx->rings_rcu->cq.tail) > > READ_ONCE(io_get_rings(ctx)->cq.tail) > > Apologies for not catching this during my review of v2. Indeed, might just fold that in. It's just a sparse complaint, but might as well get it sorted before it goes upstream. -- Jens Axboe