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From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH 3/4] sparc64: convert spinlock_t to raw_spinlock_t in
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Date: Tue, 04 Mar 2014 15:03:38 -0500 (EST)
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From: Kirill Tkhai <tkhai@yandex.ru>
Date: Wed, 19 Feb 2014 13:25:38 +0400

> It seems for me it's better to decide the problem not changing protector of tsb like in patch above.
> You may get good stack without sun4v_data_access_exception error, which was in the first or second
> message.

My suspicion is that what happens when we get the data access error is
that we sample the tlb batch count as non-zero, preempt, then come
back from preemption seeing the tlb batch in a completely different state.

And that's what leads to the crash, in the one trace I saw the TSB address
passed to tsb_flush() (register %o0) was some garbage like 0x103.