Hi Rob,
Thanks for your comment. Looking at the working omapdrm code in 3.4.25, added the spin_unlock at the start of the function sync_op_update() and again locking at the end of the function fixes this error. Does this looks correct fix?
------------------------------------------------------------------------- static void sync_op_update(void) { struct omap_gem_sync_waiter *waiter, *n; + spin_unlock(&sync_lock); //vikas list_for_each_entry_safe(waiter, n, &waiters, list) { if (!is_waiting(waiter)) { list_del(&waiter->list); SYNC("notify: %p", waiter); waiter->notify(waiter->arg); kfree(waiter); } } + spin_lock(&sync_lock); } -------------------------------------------------------------------------
Thanks & Regards, Vikas
On Wed, Apr 2, 2014 at 8:01 PM, Rob Clark robdclark@gmail.com wrote:
On Wed, Apr 2, 2014 at 8:23 AM, Vikas Patil vikasmpatil@gmail.com wrote:
Hi, I am seeing following kernel backtrace on J6 with linux 3.8.13 when
trying
to start IVI LM service. Before starting this I started the X11 and run
some
GLES2/X11 based tests successfully.
The same binaries and my graphics driver are working fine on OMAP5 and
linux
3.4.25. Is this some known BUG in omapdrm driver? If not a bug then how should I go for debugging it?
From the trace what I understood is, this is case of nested spinlock and
I
might be seeing this error due to this as in the trace
omap_gem_op_update()
and omap_gem_set_sync_object(), both functions are trying to acquire spin_lock(&sync_lock).
ok, to be fair this is more about pvr and some downstream patches to omapdrm to make it work with pvr, than the upstream omapdrm.
tbh, I don't completely remember how this used to work.. it doesn't seem like the sort of thing that could be easily missed. You might want to compare to older omapdrm+pvr, I might have moved some of the locking around?
Probably the best/safest thing would be to move the waiter->notify() callback off to omapdrm's workqueue, so it isn't called with spinlocks held.
BR, -R
[ 719.005340] BUG: spinlock lockup suspected on CPU#0, kworker/u:2/787 [ 719.011749] lock: sync_lock+0x0/0x20, .magic: dead4ead, .owner: kworker/u:2/787, .owner_cpu: 0 [ 719.020507] [<c001bbc0>] (unwind_backtrace+0x0/0x138) from
[<c02896d0>]
(do_raw_spin_lock+0x100/0x17c) [ 719.029876] [<c02896d0>] (do_raw_spin_lock+0x100/0x17c) from
[<c03157ec>]
(omap_gem_set_sync_object+0x14/0xf4) [ 719.039978] [<c03157ec>] (omap_gem_set_sync_object+0x14/0xf4) from [<bf0091f4>] (FreeMemCallBackCommon+0xf4/0x24c [omapdrm_pvr]) [ 719.051635] [<bf0091f4>] (FreeMemCallBackCommon+0xf4/0x24c
[omapdrm_pvr])
from [<bf0093d0>] (UnwrapExtMemoryCallBack+0x28/0x68 [omapdrm_pvr]) [ 719.064544] [<bf0093d0>] (UnwrapExtMemoryCallBack+0x28/0x68 [omapdrm_pvr]) from [<bf013d3c>] (FreeResourceByPtr.part.0+0xac/0xcc [omapdrm_pvr]) [ 719.077575] [<bf013d3c>] (FreeResourceByPtr.part.0+0xac/0xcc [omapdrm_pvr]) from [<bf0144d0>] (ResManFreeResByPtr+0x44/0x6c [omapdrm_pvr]) [ 719.090118] [<bf0144d0>] (ResManFreeResByPtr+0x44/0x6c [omapdrm_pvr]) from [<bf008980>] (async_unmap+0x28/0x44 [omapdrm_pvr]) [ 719.101531] [<bf008980>] (async_unmap+0x28/0x44 [omapdrm_pvr]) from [<c0315528>] (sync_op_update+0x88/0xa8) [ 719.111328] [<c0315528>] (sync_op_update+0x88/0xa8) from [<c03157c8>] (omap_gem_op_update+0x14/0x24) [ 719.120544] [<c03157c8>] (omap_gem_op_update+0x14/0x24) from
[<bf010578>]
(PVRSRVMISR+0xc/0x60 [omapdrm_pvr]) [ 719.130523] [<bf010578>] (PVRSRVMISR+0xc/0x60 [omapdrm_pvr]) from [<c005a810>] (process_one_work+0x1c8/0x5c0) [ 719.140502] [<c005a810>] (process_one_work+0x1c8/0x5c0) from
[<c005af58>]
(worker_thread+0x168/0x444) [ 719.149810] [<c005af58>] (worker_thread+0x168/0x444) from [<c005fa40>] (kthread+0xa4/0xb0) [ 719.158142] [<c005fa40>] (kthread+0xa4/0xb0) from [<c00140d0>] (ret_from_fork+0x14/0x24)
Thanking you for your time.
Thanks & Regards, Vikas