From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=216.40.44.16 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793281729; b=jY2v9ZJfbrVLWS2f8lb9F/QBzSyqIQ/2f6vFl1AqJ/Ho/PQ49Ki4hgKre2XLqZkVmIsU JxFGtOvwZea9bzEqmUZ1NtaCzYAd+wylgMg3EOF6x/ftaLYRJjK8UkDuiBVi1HH473S1I RpX8d0BNs+Kv8whuUMV52iejTSubbYS/OEQ33ApUM97mg84QIGZjS6h9Ty1T8zobleryt dy7AXGtZILpnxi7A4V5mjEoYx870cMXcl4cH28ocSh6jUD/EAhtj8IrMEIEO5NtXlJXnB PSn1kvK14Zm59El7XAI/BFrc5CTcv/hq7m0+DCsJyXfi9h5bjS/cLumMYLsK55jQ1bw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793281729; h=DMARC-Filter:Received:Received:Date:From:To:Cc:Subject:Message-ID: In-Reply-To:References:X-Mailer:MIME-Version:Content-Type: Content-Transfer-Encoding:X-Rspamd-Server:X-Rspamd-Queue-Id: X-Stat-Signature:X-Spam-Status:X-Session-Marker:X-Session-ID: DKIM-Signature:X-HE-Tag:X-HE-Meta; bh=N6vcUb6SJzRTcfauxbDiejxYjIsBkLgqIhSS3kXkYQo=; b=EjOg2V+ZPrsDHNvogeGLRDoRgEbgbSq9JA5KgohiY1T38KWO+RdtbKaJC4BGg3qgKgGY pntuEfGXwqoZ40kglBhIjeNreYVkv0NZWqC7LqZ6fSpML+C2WzoWt1uN6Qwc6XqY2qJS4 Hao2eZGbMSDnRLgQ6QTl+D+/I6qVCQfnPp0H2QhiBmR3jZkuSQDneYb675Qn1e0Xtg058 Ml+2Rjq3Xl4g3TembteDT1QyJZ2ipHQeUKzg02hWuL39erPpN5O7ezEwtufw+JQlUMKhB qzvhj4KNE13rXcrquP/SdOPb+ieEqEIlgIBYAot+9qmuN8mPrUSSHPFuoSMoikEqCdQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; dkim=pass header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b=h0khfuiX; arc=none smtp.remote-ip=216.40.44.16 Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F73F60A5BD5; Thu, 29 Oct 2026 13:48:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3F73F60A5BD5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=goodmis.org header.i=@goodmis.org header.a=rsa-sha256 header.s=dkim1 header.b=h0khfuiX Received: from omf20.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 63C87C03D9; Thu, 29 Oct 2026 13:48:46 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf20.hostedemail.com (Postfix) with ESMTPA id 33E4920026; Thu, 29 Oct 2026 13:48:44 +0000 (UTC) Date: Thu, 29 Oct 2026 09:48:42 -0400 From: Steven Rostedt To: Jens Axboe Cc: Anvik Loitongbam , Pavel Begunkov , Olivier Langlois , Sebastian Andrzej Siewior , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH] io_uring/napi: fix list use-after-free on PREEMPT_RT Message-ID: <20261029094842.58dc252d@gandalf.local.home> In-Reply-To: <502f31ed-dd70-469c-b433-577ccee36c3f@kernel.dk> References: <20261029102244.141621-1-permissiontogallop@gmail.com> <502f31ed-dd70-469c-b433-577ccee36c3f@kernel.dk> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout07 X-Rspamd-Queue-Id: 33E4920026 X-Stat-Signature: i4wa8zmaz8efohxc8xwyt1ps7bp73wox X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1/n6TvaN0U32J07q2RORdP1mOlBY1nJQIo= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=goodmis.org; h=date:from:to:cc:subject:message-id:in-reply-to:references:mime-version:content-type:content-transfer-encoding; s=dkim1; bh=N6vcUb6SJzRTcfauxbDiejxYjIsBkLgqIhSS3kXkYQo=; b=h0khfuiXO5ayJH1jQjBMv+Rg+qX+wvggPKXB+6xczdNfQjHWuHTBILhsb+UvURDzkAkrBUUbjFAFhUDnSBfxqTahJXde13xQs4PWZ9E0ag1OKJWgdhn2Z/yKUS8NTe6mgKPk33GosRzE9472jsdqmQHidvlidDlpSOIRXY+ptxE= X-HE-Tag: 1793281724-722511 X-HE-Meta: U2FsdGVkX1/tbr3Ieis1YJltcvmKNmAuEETMJT2+weDKtNQ4wcmVF9jqePB91f/lRSAVykrGmGhbdm3Upc63qLsEs5JHxaiDBNLkf9FC8VTE0VnmKVI4MIJAY0gMGclIHfMc8Dy27XYrEnOtpS370FkTJWM54Degv8zL0XLCH5mS9wU7C1cX2JfM2Tm6Ck6c7gD5EdRYtOv8O1jXuhMIU87C2ULW56pGQqM+OjbZyRq2wmdCQQuQZDwnwOtGIiBLJkMeIM3/eZKDptlFoatoqiuFq8hKtdcONcUz4ynfTZMitOrcZ3peIHvDpBaQ2LUw On Thu, 29 Oct 2026 07:42:09 -0600 Jens Axboe wrote: > I don't think your analysis is fully correct. On PREEMPT_RT, spin_lock() > should still be an RCU read side critical section. __rt_spin_lock() > calls rcu_read_lock() after taking the rtmutex, and then > rt_spin_unlock() drops it at the end. There's even a comment on > kfree_rcu() callbacks in there too, it should not be able to run until > napi_lock is released, which is post the loop. Good point. > > IOW, I think this patch is unnecessary - there's no bug there. The list > safe change could be done as a cleanup, but it's not a fix. I agree, it should still be applied, but as a clean up and not a fix. -- Steve