Hi,
Trying to find a hanging reason for a custom omap4430 board (aka nook
tablet), I stumled over a possible circular locking problem on
startup:
...
<4>[ 12.078216]
<4>[ 12.078247] =======================================================
<4>[ 12.087341] [ INFO: possible circular locking dependency detected ]
<4>[ 12.094329] 3.0.31+ #2
<4>[ 12.097290] -------------------------------------------------------
<4>[ 12.104278] kworker/0:1/58 is trying to acquire lock:
<4>[ 12.110168] ((&mq->work)){+.+.+.}, at: [<c00d2fb0>]
wait_on_work+0x0/0x1cc
<4>[ 12.118621]
<4>[ 12.118621] but task is already holding lock:
<4>[ 12.125549] (mbox_configured_lock){+.+.+.}, at: [<c009ddd4>]
omap_mbox_put+0x34/0x100
<4>[ 12.135009]
<4>[ 12.135040] which lock already depends on the new lock.
...
<4>[ 12.504486] Chain exists of:
<4>[ 12.504486] (&mq->work) --> &rproc->lock --> mbox_configured_lock
<4>[ 12.515899]
<4>[ 12.518127] Possible unsafe locking scenario:
<4>[ 12.518127]
<4>[ 12.524963] CPU0 CPU1
<4>[ 12.530242] ---- ----
<4>[ 12.535369] lock(mbox_configured_lock);
<4>[ 12.540344] lock(&rproc->lock);
<4>[ 12.547485] lock(mbox_configured_lock);
<4>[ 12.555389] lock((&mq->work));
<4>[ 12.559539]
<4>[ 12.559539] *** DEADLOCK ***
<4>[ 12.559539]
<4>[ 12.566589] 3 locks held by kworker/0:1/58:
<4>[ 12.571502] #0: (pm){.+.+..}, at: [<c00d34b8>]
process_one_work+0x124/0x590
<4>[ 12.580322] #1: ((&dev->power.work)){+.+...}, at: [<c00d34b8>]
process_one_work+0x124/0x590
<4>[ 12.590850] #2: (mbox_configured_lock){+.+.+.}, at:
[<c009ddd4>] omap_mbox_put+0x34/0x100
<4>[ 12.601165]
Full dmesg can be found here:
https://dl.dropbox.com/u/21820416/mbox-deadlock.dmesg
For the record: Kernel source is very close to p-android-3.0. It can
be found here:
https://github.com/Kuzma30/kernel3NookTablet/tree/jellybean
Used config: cyanogenmod_acclaim_defconfig.
Kind regards,
Chris
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