From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7D99943CED7; Fri, 27 Feb 2026 15:09:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772204983; cv=none; b=JKM3zLt8sKu72wgKUMFXaI4pLh8BS0zvw4ZdPETTDOh0RrcyzT3Ue0Mb8d7NN3Z1o5LV+Fg3BGSy/nNtGNQAbmaqXSEu9u1xN/vAzzOv2F8C3a65NcBG4TjQBAckh711WkJhjGqAmjPcXY0l6HeMzLxNqGUdX0e5DpUmtUWf1iw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772204983; c=relaxed/simple; bh=FBlbP3EPFUp7PQ6k0kHFG6GMgYCzGba1rNGnfgUMbf0=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=DE0uWHlgr8Mz0HxWb4DKZE2yTlMriYcfAFjersSILVw0ojVeWN2qoG4clfgNW338ZbWyzFX2nYgEWql7IdhnOam0uH+lixJUny/Qa7T2w4QXym+2G4zNnbG98sDuKn2r+x2mMCpcpPZMjdDM8J+3Rnc1aT3fyXUy6ZIQ+RfRlq0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.11 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 Received: from omf15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id D06DAC2760; Fri, 27 Feb 2026 15:09:39 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf15.hostedemail.com (Postfix) with ESMTPA id CA80618; Fri, 27 Feb 2026 15:09:37 +0000 (UTC) Date: Fri, 27 Feb 2026 10:10:02 -0500 From: Steven Rostedt To: Vincent Donnefort Cc: Qing Wang , Masami Hiramatsu , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, syzbot+3b5dd2030fe08afdf65d@syzkaller.appspotmail.com Subject: Re: [PATCH] tracing: Fix WARN_ON in tracing_buffers_mmap_close Message-ID: <20260227101002.614add75@gandalf.local.home> In-Reply-To: References: <20260227025842.1085206-1-wangqing7171@gmail.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout07 X-Rspamd-Queue-Id: CA80618 X-Stat-Signature: ofai8ftkh8g4cc86bty8mwqjxehijt6k X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1/0Ix6c0vOFhFNA4D7m8qRMfxOF/hcS3Z0= X-HE-Tag: 1772204977-4002 X-HE-Meta: U2FsdGVkX18sIeeHOEXg9oWK3WNtFoRx4xedh0dUTckl8R3N2ih8IwQktyit2tomI/4f9HF7kq+04rAPp2/wzOzJiU/dU0V6yPTygnDVYAu+iQXlSyLS/O4YA3bszu1Sy2b0a1cAxj5oSLKB0IcdQoDuu4SqXIRePyObXMpkqJy91d5HjamNKo0qYV4zZz0J+xPB8J+tyQzxGpWO3LX/JhfVHRwN96szv34UB7Ipg6svq1hacVVNqya79hxorT550EHgx5Hp0YEaYWZweqyM5ZfditGezhjFIybWghBcgK9qqyqxVTuXArouZxa8OKfsVyl6G24xC4/4AP2ptawRgX3oCVUT5ZNc On Fri, 27 Feb 2026 10:41:17 +0000 Vincent Donnefort wrote: > > Hum, not sure this is entirely correct. We do set VM_DONTCOPY when creating the > > mapping (see __rb_map_vma). So AFAICT ->open() is not called in this situation (see > > dup_mmap()) > > Ah right, Syzkaller is using madvise(MADVISE_DOFORK) which resets VM_DONTCOPY. Hmm, So this means user space can override the DONTCOPY? Can this cause bugs elsewhere that DONTCOPY is used? -- Steve