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Subject[patch 6/8 v5] 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.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
---
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.

arch/x86/include/asm/uv/uv_bau.h | 1 +
arch/x86/platform/uv/tlb_uv.c | 19 +++++++++++++++----
2 files changed, 16 insertions(+), 4 deletions(-)
Index: linux/arch/x86/include/asm/uv/uv_bau.h
===================================================================
--- linux.orig/arch/x86/include/asm/uv/uv_bau.h
+++ linux/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;
Index: linux/arch/x86/platform/uv/tlb_uv.c
===================================================================
--- linux.orig/arch/x86/platform/uv/tlb_uv.c
+++ linux/arch/x86/platform/uv/tlb_uv.c
@@ -375,13 +375,13 @@ static void reset_with_ipi(struct pnmask
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
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_
}

/*
+ * 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_socket
socket++;
socket_mask = (socket_mask >> 1);
}
+ make_per_hub_cpumask(hmaster);
}
return 0;
}


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