| Date | Sun, 08 Feb 2009 23:00:17 +0100 | From | Andrea Righi <> | Subject | Re: [Bug #12606] fb_mmap: circular locking dependency on hibernation |
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On 2009-02-08 20:21, Rafael J. Wysocki wrote: > 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=12606 > Subject : fb_mmap: circular locking dependency on hibernation > Submitter : Andrey Borzenkov <arvidjaar@mail.ru> > Date : 2009-01-27 18:37 (13 days old) > References : http://marc.info/?l=linux-kernel&m=123308162731408&w=4 > Handled-By : Andrea Righi <righi.andrea@gmail.com> > Patch : http://marc.info/?l=linux-kernel&m=123365581406194&w=2
This is fixed by:
commit 1f5e31d7e55ac7fbd4ec5e5b20c8868b0e4564c9 Author: Andrea Righi <righi.andrea@gmail.com> Date: Wed Feb 4 15:12:03 2009 -0800
fbmem: don't call copy_from/to_user() with mutex held
Avoid calling copy_from/to_user() with fb_info->lock mutex held in fbmem ioctl().
fb_mmap() is called under mm->mmap_sem (A) held, that also acquires fb_info->lock (B); fb_ioctl() takes fb_info->lock (B) and does copy_from/to_user() that might acquire mm->mmap_sem (A), causing a deadlock.
NOTE: it doesn't push down the fb_info->lock in each own driver's fb_ioctl(), so there are still potential deadlocks elsewhere.
Signed-off-by: Andrea Righi <righi.andrea@gmail.com> Cc: Dave Jones <davej@redhat.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Krzysztof Helt <krzysztof.h1@wp.pl> Cc: Harvey Harrison <harvey.harrison@gmail.com> Cc: Stefan Richter <stefanr@s5r6.in-berlin.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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