ACK / APPLIED[unstable]: [SRU][Bionic][PATCH 1/1] UBUNTU: SAUCE: powerpc/perf: Fix memory allocation for core-imc based on num_possible_cpus()
seth.forshee at canonical.com
Tue May 22 14:18:32 UTC 2018
On Fri, May 18, 2018 at 10:48:03AM -0400, Joseph Salisbury wrote:
> From: Anju T Sudhakar <anju at linux.vnet.ibm.com>
> BugLink: http://bugs.launchpad.net/bugs/1770849
> Currently memory is allocated for core-imc based on cpu_present_mask, which
> has bit 'cpu' set iff cpu is populated. We use (cpu number / threads per core)
> as as array index to access the memory. So in a system with guarded cores,
> since allocation happens based on cpu_present_mask, (cpu number / threads per core)
> bounds the index and leads to memory overflow.
> The issue is exposed in a guard test. The guard test will make some CPU's
> as un-available to the system during boot time as well as at runtime. So
> when the cpu is unavailable to the system during boot time, the memory
> allocation happens depending on the number of available cpus. And when we
> access the memory using (cpu number / threads per core) as the index the
> system crashes due to memory overflow.
> Allocating memory for core-imc based on cpu_possible_mask, which has bit
> 'cpu' set iff cpu is populatable, will fix this issue.
> Reported-by: Pridhiviraj Paidipeddi <ppaidipe at linux.vnet.ibm.com>
> Signed-off-by: Anju T Sudhakar <anju at linux.vnet.ibm.com>
> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
Acked-by: Seth Forshee <seth.forshee at canonical.com>
Applied to unstable/master, thanks!
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