Cliff
Thank you for providing the correction. It looks like the best thing to do with changed
buffer size context after adding earlier patch that I sent.
I had one observation, though it doesn't impact this issue directly. In function
copy_bitmask_to_bitmask() 3rd condition looked redundant to me. Since first 2 conditions
cover all the cases, in that situation would these conditions make sense ?
-----------------------------------------------------------------------------------------------
else {
bytes = CPU_BYTES(bmpfrom->size);
memcpy(bmpto->maskp, bmpfrom->maskp, bytes);
}
-----------------------------------------------------------------------------------------------
Do let us know when can we expect these patches upstream.
Thank you
Sharyathi
On 02/02/2010 04:07 AM, Cliff Wickman wrote:
Hi Sharyathi,
Thanks for both patch and test case.
The patch needs one more change I think.
The target buffer may be bigger, so the copy of the map needs
to be zero-extended.
Would you review it?
Thx.
-Cliff
Date: Thu, 28 Jan 2010 11:23:05 +0530
From: Sharyathi Nagesh<sharyath@xxxxxxxxxx>
To: linux-numa@xxxxxxxxxxxxxxx, Andi Kleen<andi@xxxxxxxxxxxxxx>,
Christoph Lameter<clameter@xxxxxxx>, Cliff Wickman<cpw@xxxxxxx>,
Lee Schermerhorn<lee.schermerhorn@xxxxxx>,
Amit K Arora<amitarora@xxxxxxxxxx>, deepti.kalra@xxxxxxxxxx
Subject: Fix to numa_node_to_cpus_v2
Hi
We observed that numa_node_to_cpus api() api converts a node number to a
bitmask of CPUs. The user must pass a long enough buffer. If the buffer is not
long enough errno will be set to ERANGE and -1 returned. On success 0 is returned.
This api has been changed in numa version 2.0. It has new implementation (_v2)
Analysis:
Now within the numa_node_to_cpus code there is a check if the size of buffer
passed from the user matches the one returned by the sched_getaffinity. This
check fails and hence we see "map size mismatch: abort" messages coming out on
console. My system has 4 node and 8 CPUs.
Testcase to reproduce the problem:
#include<errno.h>
#include<stdio.h>
#include<stdlib.h>
#include<numa.h>
typedef unsigned long BUF[64];
int numa_exit_on_error = 0;
void node_to_cpus(void)
{
int i;
BUF cpubuf;
BUF affinityCPUs;
int maxnode = numa_max_node();
printf("available: %d nodes (0-%d)\n", 1+maxnode, maxnode);
for (i = 0; i<= maxnode; i++) {
printf("Calling numa_node_to_cpus()\n");
printf("Size of BUF is : %d \n",sizeof(BUF));
if ( 0 == numa_node_to_cpus(i, cpubuf, sizeof(BUF)) ) {
printf("Calling numa_node_to_cpus() again \n");
if ( 0 == numa_node_to_cpus(i, cpubuf, sizeof(BUF)) ) {
} else {
printf("Got< 0 \n");
numa_error("numa_node_to_cpu");
numa_exit_on_error = 1;
exit(numa_exit_on_error);
}
} else {
numa_error("numa_node_to_cpu 0");
numa_exit_on_error = 1;
exit(numa_exit_on_error);
}
}
}
int main()
{
void node_to_cpus();
if (numa_available()< 0)
{
printf("This system does not support NUMA policy\n");
numa_error("numa_available");
numa_exit_on_error = 1;
exit(numa_exit_on_error);
}
node_to_cpus();
return numa_exit_on_error;
}
--------------------------------------------------------------------------------
Problem Fix:
The fix is to allow numa_node_to_cpus_v2() to fail only when the supplied
buffer is smaller than the bitmask required to represent online NUMA nodes.
Attaching the patch to address this issues, patch is generated against numactl-2.0.4-rc1
Regards
Yeehaw
---
libnuma.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: numactl-dev/libnuma.c
===================================================================
--- numactl-dev.orig/libnuma.c
+++ numactl-dev/libnuma.c
@@ -1272,11 +1272,11 @@ numa_node_to_cpus_v2(int node, struct bi
if (node_cpu_mask_v2[node]) {
/* have already constructed a mask for this node */
- if (buffer->size != node_cpu_mask_v2[node]->size) {
+ if (buffer->size< node_cpu_mask_v2[node]->size) {
numa_error("map size mismatch; abort\n");
return -1;
}
- memcpy(buffer->maskp, node_cpu_mask_v2[node]->maskp, bufferlen);
+ copy_bitmask_to_bitmask(node_cpu_mask_v2[node], buffer);
return 0;
}
--
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