[PATCH] Sys V shared memory limited to 8TiB.

From: Robin Holt
Date: Tue Apr 09 2013 - 22:39:31 EST

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 that 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;

Signed-off-by: Robin Holt <holt@xxxxxxx>
Reported-by: Alex Thorlton <athorlton@xxxxxxx>
To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Stable Kernel Maintainers <stable@xxxxxxxxxxxxxxx>
Cc: lkml <linux-kernel@xxxxxxxxxxxxxxx>


include/linux/ipc_namespace.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index ae221a7..ca62eca 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()

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