[ 071/136 ] ipc: sysv shared memory limited to 8TiB

Steven Rostedt
2013-05-18T03:03:04Z

[-- Attachment #1: 0071-ipc-sysv-shared-memory-limited-to-8TiB.patch --]
[-- Type: text/plain, Size: 2162 bytes --]

3.6.11.4 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Robin Holt <holt@sgi.com>

[ Upstream commit d69f3bad4675ac519d41ca2b11e1c00ca115cecd ]

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>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/ipc_namespace.h | 2 +-
ipc/shm.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 5499c92..c731973 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -42,8 +42,8 @@ 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 00faa05..9f753fc4 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;
--
1.7.10.4