ipcshm-document-new-limits-in-the-uapi-header-v3

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/uapi/linux/shm.h b/include/uapi/linux/shm.h
index 3400b6eb1fbe9dfe539358ecb07c7def156db2e1..1fbf24ea37fdcf63f1da6ccfc5944ac6f21e299f 100644 (file)
--- a/include/uapi/linux/shm.h
+++ b/include/uapi/linux/shm.h
@@ -8,13 +8,13 @@
 #endif
 
 /*
- * SHMMNI, SHMMAX and SHMALL are the default upper limits which can be
- * modified by sysctl. Both SHMMAX and SHMALL have their default values
- * to the maximum limit which is as large as it can be without helping
- * userspace overflow the values. There is really nothing the kernel
- * can do to avoid this any further. It is therefore not advised to
- * make them any larger. These limits are suitable for both 32 and
- * 64-bit systems.
+ * SHMMNI, SHMMAX and SHMALL are default upper limits which can be
+ * modified by sysctl. The SHMMAX and SHMALL values have been chosen to
+ * be as large possible without facilitating scenarios where userspace
+ * causes overflows when adjusting the limits via operations of the form
+ * "retrieve current limit; add X; update limit". It is therefore not
+ * advised to make SHMMAX and SHMALL any larger. These limits are
+ * suitable for both 32 and 64-bit systems.
  */
 #define SHMMIN 1                        /* min shared seg size (bytes) */
 #define SHMMNI 4096                     /* max num of segs system wide */