x86, UV: Remove cpumask_t from the stack

Remove the large stack-resident cpumask_t from
reset_with_ipi()'s stack by allocating one per uvhub.

Due to the limited size of the stack the potentially huge cpumask_t may
cause stack overrun.  We haven't seen it happen yet, but we need to make it
a practice not to push such structures onto the stack.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Link: http://lkml.kernel.org/r/20110621122242.832589130@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 16 insertions, 4 deletions

diff --git a/arch/x86/include/asm/uv/uv_bau.h b/arch/x86/include/asm/uv/uv_bau.h
index fa6a48e264b3..16ce58c6d252 100644
--- a/arch/x86/include/asm/uv/uv_bau.h
+++ b/arch/x86/include/asm/uv/uv_bau.h
@@ -488,6 +488,7 @@ struct bau_control {
         struct bau_control      *uvhub_master;
         struct bau_control      *socket_master;
         struct ptc_stats        *statp;
+        cpumask_t               *cpumask;
         unsigned long           timeout_interval;
         unsigned long           set_bau_on_time;
         atomic_t                active_descriptor_count;
diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 191ef28ea173..5265842b8d0b 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -375,13 +375,13 @@ static void reset_with_ipi(struct pnmask *distribution, struct bau_control *bcp)
         int pnode;
         int apnode;
         int maskbits;
-        cpumask_t mask;
         int sender = bcp->cpu;
+        cpumask_t *mask = bcp->uvhub_master->cpumask;
         struct bau_control *smaster = bcp->socket_master;
         struct reset_args reset_args;
 
         reset_args.sender = sender;
-        cpus_clear(mask);
+        cpus_clear(*mask);
         /* find a single cpu for each uvhub in this distribution mask */
         maskbits = sizeof(struct pnmask) * BITSPERBYTE;
         /* each bit is a pnode relative to the partition base pnode */
@@ -391,11 +391,11 @@ static void reset_with_ipi(struct pnmask *distribution, struct bau_control *bcp)
                         continue;
                 apnode = pnode + bcp->partition_base_pnode;
                 cpu = pnode_to_first_cpu(apnode, smaster);
-                cpu_set(cpu, mask);
+                cpu_set(cpu, *mask);
         }
 
         /* IPI all cpus; preemption is already disabled */
-        smp_call_function_many(&mask, do_reset, (void *)&reset_args, 1);
+        smp_call_function_many(mask, do_reset, (void *)&reset_args, 1);
         return;
 }
 
@@ -1696,6 +1696,16 @@ static void make_per_cpu_thp(struct bau_control *smaster)
 }
 
 /*
+ * Each uvhub is to get a local cpumask.
+ */
+static void make_per_hub_cpumask(struct bau_control *hmaster)
+{
+        int sz = sizeof(cpumask_t);
+
+        hmaster->cpumask = kzalloc_node(sz, GFP_KERNEL, hmaster->osnode);
+}
+
+/*
  * Initialize all the per_cpu information for the cpu's on a given socket,
  * given what has been gathered into the socket_desc struct.
  * And reports the chosen hub and socket masters back to the caller.
@@ -1765,6 +1775,7 @@ static int __init summarize_uvhub_sockets(int nuvhubs,
                         socket++;
                         socket_mask = (socket_mask >> 1);
                 }
+                make_per_hub_cpumask(hmaster);
         }
         return 0;
 }