On Sat, Jan 18, 2014 at 07:25:51AM +0000, naveen yadav wrote: > We are using 3.8.x kernel on ARM, We are facing soft lockup issue. > Following are the logs.
Which CPU/SoC are you using? > BUG: spinlock lockup suspected on CPU#0, process1/525 > lock: 0xd8ac9a64, .magic: dead4ead, .owner: <none>/-1, .owner_cpu: -1 > > > 1 . Looks like lock is available as owner is -1, why arch_spin_trylock > is getting failed ? Is this with or without the ticket lock patches? Can you inspect the actual value of the arch_spinlock_t? > 2. There is a patch : ARM: spinlock: retry trylock operation if strex > fails on free lock > http://permalink.gmane.org/gmane.linux.ports.arm.kernel/240913 > In this patch, A loop has been added around strexeq %2, %0, [%3]". > {Comment "retry the trylock operation if the lock appears > to be free but the strex reported failure"} > > but arch_spin_trylock is called by __spin_lock_debug and its already > getting called in loops. So what purpose is resolves? Does this patch help your issue? The purpose of it is to distinguish between two types of contention: (1) The lock is actually taken (2) The lock is free, but two people are doing a trylock at the same time In the case of (2), we do actually want to spin again otherwise you could potentially end up in a pathological case where the two CPUs repeatedly shoot down each other's monitor and forward progress isn't made until the sequence is broken by something like an interrupt. > static void __spin_lock_debug(raw_spinlock_t *lock) > { > u64 i; > u64 loops = loops_per_jiffy * HZ; > > for (i = 0; i < loops; i++) { > if (arch_spin_trylock(&lock->raw_lock)) > return; > __delay(1); > } > /* lockup suspected: */ > spin_dump(lock, "lockup suspected"); > } > > 3. Is this patch useful to us, How can we reproduce this scenario ? > Scenario : Lock is available but arch_spin_trylock is returning as failure Potentially. Why can't you simply apply the patch and see if it resolves your issue? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
