[PATCH] SHM_NORESERVE flags for shmget()
Add SHM_NORESERVE functionality similar to MAP_NORESERVE for shared memory
segments.
This is mainly to avoid abuse of OVERCOMMIT_ALWAYS and this flag is ignored
for OVERCOMMIT_NEVER.
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/shm.h b/include/linux/shm.h
index 80113a1..a2c896a 100644
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -92,6 +92,7 @@
#define SHM_DEST 01000 /* segment will be destroyed on last detach */
#define SHM_LOCKED 02000 /* segment will not be swapped */
#define SHM_HUGETLB 04000 /* segment will use huge TLB pages */
+#define SHM_NORESERVE 010000 /* don't check for reservations */
#ifdef CONFIG_SYSVIPC
long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr);
diff --git a/ipc/shm.c b/ipc/shm.c
index b58c651..587d836 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -212,8 +212,16 @@
file = hugetlb_zero_setup(size);
shp->mlock_user = current->user;
} else {
+ int acctflag = VM_ACCOUNT;
+ /*
+ * Do not allow no accounting for OVERCOMMIT_NEVER, even
+ * if it's asked for.
+ */
+ if ((shmflg & SHM_NORESERVE) &&
+ sysctl_overcommit_memory != OVERCOMMIT_NEVER)
+ acctflag = 0;
sprintf (name, "SYSV%08x", key);
- file = shmem_file_setup(name, size, VM_ACCOUNT);
+ file = shmem_file_setup(name, size, acctflag);
}
error = PTR_ERR(file);
if (IS_ERR(file))