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Wed, 13 May 2026 13:02:02 -0700 (PDT) Received: from google.com ([2a00:79e0:2ebe:8:e25b:b38f:c027:f0cb]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-134cc33a618sm666176c88.12.2026.05.13.13.02.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 May 2026 13:02:01 -0700 (PDT) Date: Wed, 13 May 2026 13:01:58 -0700 From: Dmitry Torokhov To: Rik van Riel Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] input/evdev: move kill_fasync() outside buffer_lock to fix SOFTIRQ deadlock Message-ID: References: <20260513115000.77ec5975@fangorn> Precedence: bulk X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260513115000.77ec5975@fangorn> Hi Rik, On Wed, May 13, 2026 at 11:50:00AM -0400, Rik van Riel wrote: > buffer_lock is a SOFTIRQ-safe spinlock. kill_fasync() acquires fa_lock > (SOFTIRQ-unsafe), creating a potential SOFTIRQ-safe->SOFTIRQ-unsafe lock > ordering violation that lockdep flags as a deadlock. > > Fix by moving the kill_fasync() call to evdev_pass_values() after > buffer_lock is released, alongside the existing wake_up_interruptible_poll(). > > The wakeup condition check is the same in __pass_event() and > evdev_pass_values() Does this really fix anything? This code is running holding input->event_lock with IRQs off... Thanks. -- Dmitry