On Thu, 2010-02-04 at 16:09 -0800, Andrew Morton wrote: > On Fri, 5 Feb 2010 01:18:15 +0200 Maxim Levitsky <maximlevitsky@xxxxxxxxx> 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 Sorry for describing this poorly. The steps are: -> Have a kernel with CONFIG_MMC_UNSAFE_RESUME -> Insert MMC/SD card -> Suspend/hibernate the system -> While system is hibernated/suspended pull the card off -> Resume the system -> Hang if CONFIG_MMC_UNSAFE_RESUME is set, mmc core allows the user to suspend/resume the card normally assuming he won't change the card or modify it in another system. The former case is actually handled quite well. if CONFIG_MMC_UNSAFE_RESUME isn't set, it removes the card during suspend, and I now think (and will test) that this will still hang the system this time on suspend. Maybe we can make del_disk behave well if called with userspace frozen? After all if user calls it, very likely that hardware is absent thus there is no point in syncing (which I think triggers the hang).... Best regards, Maxim Levitsky -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
