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x86/UV: Fix NULL pointer dereference in uv_flush_tlb_others() if the 'nobau' boot option is used 

The SGI UV tlb shootdown code panics the system with a NULL
pointer deference if 'nobau' is specified on the boot
commandline.

uv_flush_tlb_other() gets called for every flush, whether the
BAU is disabled or not.  It should not be keeping the s_enters
statistic while the BAU is disabled.

The panic occurs because during initialization
init_per_cpu_tunables() does not set the bcp->statp pointer if
'nobau' was specified.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: <stable@vger.kernel.org> # 3.12.x
Link: http://lkml.kernel.org/r/E1VnzBi-0005yF-MU@eag09.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
cpw 2013-12-03 17:15:30 -06:00 committed by Ingo Molnar
parent 8b3b005d67
commit 3eae49ca89
1 changed files with 3 additions and 2 deletions
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5
arch/x86/platform/uv/tlb_uv.c
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@ -1070,12 +1070,13 @@ const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
unsigned long status;
bcp = &per_cpu(bau_control, cpu);
stat = bcp->statp;
stat->s_enters++;
if (bcp->nobau)
return cpumask;
stat = bcp->statp;
stat->s_enters++;
if (bcp->busy) {
descriptor_status =
read_lmmr(UVH_LB_BAU_SB_ACTIVATION_STATUS_0);