Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752366Ab0BEKRm (ORCPT ); Fri, 5 Feb 2010 05:17:42 -0500 Received: from smtp.nokia.com ([192.100.122.230]:57498 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751005Ab0BEKRk (ORCPT ); Fri, 5 Feb 2010 05:17:40 -0500 Message-ID: <4B6BF02A.2080501@nokia.com> Date: Fri, 05 Feb 2010 12:17:14 +0200 From: Adrian Hunter User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: Andrew Morton CC: Maxim Levitsky , "linux-mmc@vger.kernel.org" , Philip Langdale , linux-kernel , "Schummer Jorg.2 (EXT-Tieto/Espoo)" , nico@fluxnic.net, nico@marvell.com Subject: Re: [PATCH] MMC: fix hang if card was removed during suspend and unsafe resume was enabled References: <1265219241.12549.8.camel@maxim-laptop> <1265325495-4220-1-git-send-email-maximlevitsky@gmail.com> <20100204160957.1c51cc1b.akpm@linux-foundation.org> In-Reply-To: <20100204160957.1c51cc1b.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 05 Feb 2010 10:17:16.0222 (UTC) FILETIME=[64323DE0:01CAA64C] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2942 Lines: 81 ext Andrew Morton wrote: > On Fri, 5 Feb 2010 01:18:15 +0200 Maxim Levitsky wrote: > >> Currently removal of the card leads to del_disk called indirectly by mmc core. >> This function expects userspace to be running, which isn't when .resume is called >> >> Fix that by removing the code that did that in mmc_resume_host. It is possible >> because card detection logic will kick it later and remove the card. > > I don't really understand. The above implies that to trigger this bug, > one needs to physically remove the card during a resume operation. ie: > a human-vs-computer race. Sounds unlikely? > > So... exactly what steps does the user need to take to trigger this > bug? > >> Also make mtd workqueue freezeable, so it won't attempt to add/remove the card >> while userspace is frozen. >> >> >> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c >> index 30acd52..879d48d 100644 >> --- a/drivers/mmc/core/core.c >> +++ b/drivers/mmc/core/core.c >> @@ -1257,7 +1257,6 @@ int mmc_suspend_host(struct mmc_host *host, pm_message_t state) >> if (host->caps & MMC_CAP_DISABLE) >> cancel_delayed_work(&host->disable); >> cancel_delayed_work(&host->detect); >> - mmc_flush_scheduled_work(); >> >> mmc_bus_get(host); >> if (host->bus_ops && !host->bus_dead) { >> @@ -1300,15 +1299,11 @@ int mmc_resume_host(struct mmc_host *host) >> mmc_select_voltage(host, host->ocr); >> BUG_ON(!host->bus_ops->resume); >> err = host->bus_ops->resume(host); >> + >> if (err) { >> printk(KERN_WARNING "%s: error %d during resume " >> "(card was removed?)\n", >> mmc_hostname(host), err); >> - if (host->bus_ops->remove) >> - host->bus_ops->remove(host); >> - mmc_claim_host(host); >> - mmc_detach_bus(host); >> - mmc_release_host(host); > > afacit that code's been there since March 2009. I'd have thought that > someone would have noticed "kernel hangs on resume" before now. > > Do you think the patch should be backported into 2.6.32.x and eariler? It looks like the code was introduced in 2.6.32.x by commit 95cdfb72b9bc568803f395c266152c71b034b461 cc'ing the author Nicolas Pitre > >> /* no need to bother upper layers */ >> err = 0; >> } >> @@ -1332,7 +1327,7 @@ static int __init mmc_init(void) >> { >> int ret; >> >> - workqueue = create_singlethread_workqueue("kmmcd"); >> + workqueue = create_freezeable_workqueue("kmmcd"); >> if (!workqueue) >> return -ENOMEM; > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/