]> git.karo-electronics.de Git - linux-beck.git/commit
powerpc: Set paca->data_offset = 0 for boot cpu
authorMichael Ellerman <michael@ellerman.id.au>
Thu, 20 Sep 2012 22:07:58 +0000 (22:07 +0000)
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>
Thu, 27 Sep 2012 02:51:06 +0000 (12:51 +1000)
commit466921c5a4669f4315528a25f9afd66601ce2c04
tree188c0c3517d0151e5f20a0df7ec9efc8b2541aa1
parente6878835ac4794f25385522d29c634b7bbb7cca9
powerpc: Set paca->data_offset = 0 for boot cpu

In commit 407821a we assigned a poison value to the paca->data_offset.

Unfortunately with CONFIG_LOCK_STAT=y lockdep will read & write to percpu
data very early in boot, prior to us initialising the percpu areas,
leading to a crash.

We have been getting away with this because the data_offset was previously
set to zero. This causes lockdep to read & write to the initial copy of
the percpu variables, which are discarded later in boot.

Although that is "fishy", it does work, and for lock statistics it is no
big deal to discard the counts from early boot.

So set the paca->data_offset = 0 for the boot cpu paca only.

Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
arch/powerpc/kernel/setup_64.c