From: Cliff Wickman <cpw@xxxxxxx>
A customer used this example from the numactl.8 man page:
numactl --offset=1G --length=1G --membind=1 --file /dev/shm/A --touch
intending to cause a 1G allocation of memory on node 1.
But they had only allocated a 1G /dev/shm/A file to begin with.
In this case numactl fails with a SIGBUS.
I don't think this example intended to imply that the --touch would
extend a tmpfs file. Correct me if I'm wrong.
Either way, numactl should avoid dying from a SIBUS.
This patch:
- Changes the example in numactl.8 for placing a tmpfs file.
- Enhances checks of shm address/offset/length before addressing or mmap'ing
of the shm region. This prevents invalid mmap calls and SIGBUS's.
- The options to numactl are position dependent, which can confuse a user.
So the warning messages are clarified.
Signed-off-by: Cliff Wickman <cpw@xxxxxxx>
---
numactl.8 | 6 ++++--
numactl.c | 18 +++++++++++++++---
shm.c | 16 +++++++++++-----
shm.h | 4 ++--
4 files changed, 32 insertions(+), 12 deletions(-)
Index: numactl-test.x86_64/numactl.c
===================================================================
--- numactl-test.x86_64.orig/numactl.c
+++ numactl-test.x86_64/numactl.c
@@ -356,6 +356,16 @@ void get_short_opts(struct option *o, ch
*s = '\0';
}
+void check_shmbeyond(char *msg)
+{
+ if (shmoffset >= shmlen) {
+ fprintf(stderr,
+ "numactl: region offset %#llx beyond its length %#llx at %s\n",
+ shmoffset, shmlen, msg);
+ exit(1);
+ }
+}
+
int main(int ac, char **av)
{
int c, i, nnodes=0;
@@ -478,13 +488,13 @@ int main(int ac, char **av)
case 'S': /* --shm */
check_cpubind(did_cpubind);
nopolicy();
- attach_sysvshm(optarg);
+ attach_sysvshm(optarg, "--shm");
shmattached = 1;
break;
case 'f': /* --file */
check_cpubind(did_cpubind);
nopolicy();
- attach_shared(optarg);
+ attach_shared(optarg, "--file");
shmattached = 1;
break;
case 'L': /* --length */
@@ -533,6 +543,7 @@ int main(int ac, char **av)
case 'T': /* --touch */
needshm("--touch");
+ check_shmbeyond("--touch");
numa_police_memory(shmptr, shmlen);
break;
@@ -540,6 +551,7 @@ int main(int ac, char **av)
needshm("--verify");
if (set_policy < 0)
complain("Need a policy first to verify");
+ check_shmbeyond("--verify");
numa_police_memory(shmptr, shmlen);
if (!mask)
complain("Need a mask to verify");
@@ -551,7 +563,7 @@ int main(int ac, char **av)
usage();
}
}
-
+
av += optind;
ac -= optind;
Index: numactl-test.x86_64/shm.c
===================================================================
--- numactl-test.x86_64.orig/shm.c
+++ numactl-test.x86_64/shm.c
@@ -61,12 +61,18 @@ long huge_page_size(void)
return getpagesize();
}
-static void check_region(void)
+static void check_region(char *opt)
{
if (((unsigned long)shmptr % shm_pagesize) || (shmlen % shm_pagesize)) {
fprintf(stderr, "numactl: policy region not page aligned\n");
exit(1);
}
+ if (!shmlen) {
+ fprintf(stderr,
+ "numactl: policy region length not specified before %s\n",
+ opt);
+ exit(1);
+ }
}
static key_t sysvkey(char *name)
@@ -89,7 +95,7 @@ static key_t sysvkey(char *name)
}
/* Attach a sysv style shared memory segment. */
-void attach_sysvshm(char *name)
+void attach_sysvshm(char *name, char *opt)
{
struct shmid_ds s;
key_t key = sysvkey(name);
@@ -120,11 +126,11 @@ void attach_sysvshm(char *name)
shm_pagesize = (shmflags & SHM_HUGETLB) ? huge_page_size() : getpagesize();
- check_region();
+ check_region(opt);
}
/* Attach a shared memory file. */
-void attach_shared(char *name)
+void attach_shared(char *name, char *opt)
{
struct stat64 st;
@@ -150,7 +156,7 @@ void attach_shared(char *name)
shm_pagesize = st.st_blksize;
- check_region();
+ check_region(opt);
/* RED-PEN For shmlen > address space may need to map in pieces.
Left for some poor 32bit soul. */
Index: numactl-test.x86_64/shm.h
===================================================================
--- numactl-test.x86_64.orig/shm.h
+++ numactl-test.x86_64/shm.h
@@ -9,8 +9,8 @@ extern int shmflags;
extern void dump_shm(void);
extern void dump_shm_nodes(void);
-extern void attach_shared(char *);
-extern void attach_sysvshm(char *);
+extern void attach_shared(char *, char *);
+extern void attach_sysvshm(char *, char *);
extern void verify_shm(int policy, struct bitmask *);
/* in numactl.c */
Index: numactl-test.x86_64/numactl.8
===================================================================
--- numactl-test.x86_64.orig/numactl.8
+++ numactl-test.x86_64/numactl.8
@@ -261,8 +261,10 @@ numactl --interleave=all --shmkeyfile /t
Interleave all of the sysv shared memory region specified by
/tmp/shmkey over all nodes.
-numactl --offset=1G --length=1G --membind=1 --file /dev/shm/A --touch
-Bind the second gigabyte in the tmpfs file /dev/shm/A to node 1.
+Place a tmpfs file on 2 nodes:
+ numactl --membind=2 dd if=/dev/zero of=/dev/shm/A bs=1M count=1024
+ numactl --membind=3 dd if=/dev/zero of=/dev/shm/A seek=1024 bs=1M count=1024
+
numactl --localalloc /dev/shm/file
Reset the policy for the shared memory file
--
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