ipc: sysv shared memory limited to 8TiB

Trying to run an application which was trying to put data into half of
memory using shmget(), we found that having a shmall value below 8EiB-8TiB
would prevent us from using anything more than 8TiB.  By setting
kernel.shmall greater than 8EiB-8TiB would make the job work.

In the newseg() function, ns->shm_tot which, at 8TiB is INT_MAX.

ipc/shm.c:
 458 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 459 {
...
 465         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
...
 474         if (ns->shm_tot + numpages > ns->shm_ctlall)
 475                 return -ENOSPC;

[akpm@linux-foundation.org: make ipc/shm.c:newseg()'s numpages size_t, not int]
Signed-off-by: Robin Holt <holt@sgi.com>
Reported-by: Alex Thorlton <athorlton@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index ae221a7b5092..c4d870b0d5e6 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -43,8 +43,8 @@ struct ipc_namespace {
 
         size_t          shm_ctlmax;
         size_t          shm_ctlall;
+        unsigned long   shm_tot;
         int             shm_ctlmni;
-        int             shm_tot;
         /*
          * Defines whether IPC_RMID is forced for _all_ shm segments regardless
          * of shmctl()
diff --git a/ipc/shm.c b/ipc/shm.c
index cb858df061d3..8247c49ec073 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -462,7 +462,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
         size_t size = params->u.size;
         int error;
         struct shmid_kernel *shp;
-        int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
+        size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
         struct file * file;
         char name[13];
         int id;