From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from netrider.rowland.org (netrider.rowland.org [192.131.102.5]) by smtp.subspace.kernel.org (Postfix) with SMTP id B2185131736 for ; Tue, 4 Jun 2024 14:20:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.131.102.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717510840; cv=none; b=jshoXkF3gASK2xKsIhPABlL1ecCrZ6d9k2ly2zd658ImiHwEJAiQL7lkNQntNGLw8tGuBVxnlMjTNMgZcYLuA8LufaJJJS+rPqEU+DPus+9+0IAfsukwvbmiYeOEvKGlw1oILPBjkI7nba1YScMBGpAjZnkYye5XJw7nRico6BI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717510840; c=relaxed/simple; bh=x9CkWTxGLFPRYVUUOKNEAhRFOItGOxVF5wXD2HSaC14=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=PF4pYFxJ+itNBRGsEg0AVeoAJ0TbbpmKox3Kq9HLXjfJpOcjBfxbT1pnxZRwWnNq/ArgKRwPsuRzrHPV2BtjeAVxLSWpBH3JTCwoMUs2Q72VqBQ6gMHc0rpx2GL4eZUYYyyOtlBDTUkXMCLo6eWs14kQlUuIoqaP2tXeFgcQnjQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=rowland.harvard.edu; spf=pass smtp.mailfrom=netrider.rowland.org; arc=none smtp.client-ip=192.131.102.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=rowland.harvard.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netrider.rowland.org Received: (qmail 158307 invoked by uid 1000); 4 Jun 2024 10:20:31 -0400 Date: Tue, 4 Jun 2024 10:20:31 -0400 From: Alan Stern To: Marcello Sylvester Bauer Cc: syzbot , bp@alien8.de, dave.hansen@linux.intel.com, gregkh@linuxfoundation.org, hpa@zytor.com, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, mingo@redhat.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, x86@kernel.org, Matthias Stoeckl , Uwe Kleine-Koenig Subject: Re: [syzbot] [usb?] INFO: rcu detected stall in schedule_timeout (6) Message-ID: <3e1b188f-2a68-461c-9b7c-a1d85bf8eb31@rowland.harvard.edu> References: <000000000000f8112e0618995e6e@google.com> <46cbe0a914065917ea1024636e864a1e2c982145.camel@9elements.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <46cbe0a914065917ea1024636e864a1e2c982145.camel@9elements.com> On Tue, Jun 04, 2024 at 02:05:12PM +0200, Marcello Sylvester Bauer wrote: > Greetings, > > I'm currently investigating this regression to properly fix it. My > patch only replaces the corresponding timer API calls without actually > changing the code. I'm trying to get it to work properly with the > hrtimer API. > > Any hints on how to accomplish this are welcome. Start by figuring out what isn't getting executed. That is, which USB (or usb_request) transfer isn't completing. Once you know that, see what timer callbacks do occur (if any) and figure out why they don't cause the transfer to complete. If there are no timer callbacks at all when the hang occurs, make a record (printk if nothing else), from the start of the test, of each callback and each timer restart, so you can definitively prove to the hrtimer maintainers that there's a restart with no later callback. Then it will be up to them to figure out what's going wrong. Alan Stern