powerpc/mm: Fixup preempt underflow with huge pages
hugepd_free() used __get_cpu_var() once. Nothing ensured that the code accessing the variable did not migrate from one CPU to another and soon this was noticed by Tiejun Chen in 94b09d75 ("powerpc/hugetlb: Replace __get_cpu_var with get_cpu_var"). So we had it fixed. Christoph Lameter was doing his __get_cpu_var() replaces and forgot PowerPC. Then he noticed this and sent his fixed up batch again which got applied as 69111bac ("powerpc: Replace __get_cpu_var uses"). The careful reader will noticed one little detail: get_cpu_var() got replaced with this_cpu_ptr(). So now we have a put_cpu_var() which does a preempt_enable() and nothing that does preempt_disable() so we underflow the preempt counter. Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Christoph Lameter <cl@linux.com> Cc: stable@vger.kernel.org Signed-off-by:Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by:
Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au>
parent
f55532a0
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