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Fri, 13 Nov 2026 03:33:16 -0800 (PST) Received: from gmail.com ([2a03:2880:24ff:6::]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8b4aa958d0asm17666217b3.22.2026.11.13.03.33.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2026 03:33:16 -0800 (PST) Date: Fri, 13 Nov 2026 03:33:14 -0800 From: Breno Leitao To: Yuichiro Goto Cc: a.hindborg@kernel.org, viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] configfs: wait for pending RCU callbacks on module exit Message-ID: References: <20261113033833.124797-1-goto@k-tech.co.jp> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261113033833.124797-1-goto@k-tech.co.jp> On Fri, Nov 13, 2026 at 12:38:33PM +0900, Yuichiro Goto wrote: > configfs inodes are freed from an RCU callback: destroy_inode() queues > i_callback() with call_rcu(), and i_callback() then calls the > ->free_inode() of the super block, configfs_free_inode(). Nothing in > configfs_exit() waits for these callbacks, so the module can go away > while some of them are still pending, and they later jump into freed > module text. Is this still the case on mainline? Since commit 3bc999d944b3 ("mm/slab: introduce kfree_rcu_nolock()") in v7.3, kmem_cache_destroy() calls rcu_barrier() unconditionally, and configfs_exit() already reaches it: configfs_exit() kmem_cache_destroy(configfs_dir_cachep) kvfree_rcu_barrier_on_cache() rcu_barrier() so the pending configfs_free_inode() calls finish before configfs_exit() returns.