ipc: sysv shared memory limited to 8TiB

commit d69f3bad4675ac519d41ca2b11e1c00ca115cecd upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 8a297a5e794cc8e51c22351098b80a35ce43ef09..497c6cc8848fc13ae825d3173f791c1bd48d22d3 100644 (file)
--- 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 b76be5bda6c2f10fd98019bea5730c24b7614e98..326a20bdba3ab6938267b33ffbd7cda2d970e3df 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -450,7 +450,7 @@ 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;