Commit d69f3bad authored by Robin Holt's avatar Robin Holt Committed by Linus Torvalds

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.

 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;

[ make ipc/shm.c:newseg()'s numpages size_t, not int]
Signed-off-by: default avatarRobin Holt <>
Reported-by: default avatarAlex Thorlton <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 41239fe8
......@@ -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()
......@@ -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;
Markdown is supported
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment