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Date: Sat, 25 Oct 2008 11:12:26 +0200 From: Stefan Richter <stefanr@...6.in-berlin.de> To: Johannes Weiner <hannes@...urebad.de> CC: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Andrea Righi <righi.andrea@...il.com>, Dave Jones <davej@...hat.com>, Dave Airlie <airlied@...hat.com> Subject: Re: lockdep splat from ioctl and mmap fops sharing lock Johannes Weiner wrote: > Stefan Richter <stefanr@...6.in-berlin.de> writes: > >> Johannes Weiner wrote: >>> raw1394_ioctl() doing usercopy under fi->state_mutex >>> raw1394_mmap() taking fi->state_mutex under mmap_sem ... >> was the usage of mmap_sem changed after 2.6.27 or were my tests >> insufficient? > > In linux-next/-mm, copy_to/from_user have lockdep annotations telling > that they might fault and therefor acquire the mmap_sem in #PF. > > But since faults on ioctl parameters are so rare, without these > annotations you would probably never see a warning. Thanks for the report and explanation. I logged this as http://bugzilla.kernel.org/show_bug.cgi?id=11823 (dv1394, won't fix) and http://bugzilla.kernel.org/show_bug.cgi?id=11824 (raw1394, to be fixed in the 2.6.28-rc timeframe since it is a post 2.6.27 regression). -- Stefan Richter -=====-==--- =-=- ==--= http://arcgraph.de/sr/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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