http://bugzilla.kernel.org/show_bug.cgi?id=12419
------- Comment #5 from r...@sisk.pl 2009-02-16 12:43 ------- On Monday 16 February 2009, Wang Chen wrote: > Rafael J. Wysocki said the following on 2009-2-15 4:38: > > This message has been generated automatically as a part of a report > > of recent regressions. > > > > The following bug entry is on the current list of known regressions > > from 2.6.28. Please verify if it still should be listed and let me know > > (either way). > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=12419 > > Subject : possible circular locking dependency on i915 dma > > Submitter : Wang Chen <wangc...@cn.fujitsu.com> > > Date : 2009-01-08 14:11 (38 days old) > > References : http://marc.info/?l=linux-kernel&m=123142399720125&w=4 > > > > > > Yes. It's still there in mainline. > I think the commit 546b0974c39657017407c86fe79811100b60700d > "i915: Use struct_mutex to protect ring in GEM mode." brought this regression. > > The lockdep problem is as following: > thread-1 > i915_cmdbuffer() > | > ---> lock(drm_device->struct_mutex) > | > V > i915_dispatch_cmdbuffer() > | > ---->i915_emit_box() > | > ----->copy_from_user() > | > -----might_fault() > | > --->lock(mm->mmap_sem) > > thread-2 > dup_mm() > | > --->lock(mm->mmap_sem) > | > V > drm_vm_open() > | > -------> lock(drm_device->struct_mutex) > > The different order to lock "mmap_sem" and "drm_dev->struct_mutex" introduces > the problem. > But it seems no way to reverse the lock order in i915. > So how about refine the lock granularity of drm_dev->struct_mutex and exclude > the mmap_sem > lock/unlock out of the drm_dev->struct_mutex lock/unlock range? -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. ------------------------------------------------------------------------------ Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H -- _______________________________________________ Dri-devel mailing list Dri-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/dri-devel
