Skip to contentSkip to conversation

ipc: add shm_locked for IPC shm

RFC PATCH New Hiroshi Shimamoto 1 participant 1 message Apr 9, 2008 Proc sysctl

lore
Share & tools
lore

Hiroshi Shimamoto

author
#0 lore raw

RFC PATCH 1/1 ipc: add shm_locked for IPC shm

From: Hiroshi Shimamoto <[email protected]>

Shared memory users probably don't think the shared memory is swapped out. But actually shared memory could be swapped out under memory pressure.
Linux has SHM_LOCK feature for prevent shared memory swapping, and it can be used by shmctl() after create the shared memory. There are some needs that SHM_LOCK is default behavior.

This patch adds shm_locked sysctl to turn SHM_LOCK on when creating. kernel.shm_locked = 0, is default and the behavior is not changed. kernel.shm_locked = 1, means shared memory will be locked when it's created.

Signed-off-by Hiroshi Shimamoto <[email protected]>
---
 include/linux/ipc_namespace.h |    1 +
 include/linux/sysctl.h        |    1 +
 ipc/ipc_sysctl.c              |    9 +++++
 ipc/shm.c                     |   70 ++++++++++++++++++++++++----------------
 kernel/sysctl_check.c         |    2 +
 5 files changed, 55 insertions(+), 28 deletions(-)
include/linux/ipc_namespace.h +1 -0
index e4451d1..1323985 100644
@@ -29,6 +29,7 @@ struct ipc_namespace {
 	size_t		shm_ctlmax;
 	size_t		shm_ctlall;
 	int		shm_ctlmni;
+	int		shm_ctllocked;
 	int		shm_tot;
 };
include/linux/sysctl.h +1 -0
index 571f01d..434c207 100644
@@ -163,6 +163,7 @@ enum
 	KERN_MAX_LOCK_DEPTH=74,
 	KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */
 	KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */
+	KERN_SHMLOCKED=77,	/* int: make shared memory locked */
 };
ipc/ipc_sysctl.c +9 -0
index 7f4235b..00d43b2 100644
@@ -123,6 +123,15 @@ static struct ctl_table ipc_kern_table[] = {
 		.strategy	= sysctl_ipc_data,
 	},
 	{
+		.ctl_name	= KERN_SHMLOCKED,
+		.procname	= "shm_locked",
+		.data		= &init_ipc_ns.shm_ctllocked,
+		.maxlen		= sizeof (init_ipc_ns.shm_ctllocked),
+		.mode		= 0644,
+		.proc_handler	= proc_ipc_dointvec,
+		.strategy	= sysctl_ipc_data,
+	},
+	{
 		.ctl_name	= KERN_MSGMAX,
 		.procname	= "msgmax",
 		.data		= &init_ipc_ns.msg_ctlmax,
ipc/shm.c +42 -28

100 lines not on this page · raw message

kernel/sysctl_check.c +2 -0
index c09350d..3d13649 100644
@@ -104,6 +104,8 @@ static const struct trans_ctl_table trans_kern_table[] = {
 	{ KERN_MAX_LOCK_DEPTH,		"max_lock_depth" },
 	{ KERN_NMI_WATCHDOG,		"nmi_watchdog" },
 	{ KERN_PANIC_ON_NMI,		"panic_on_unrecovered_nmi" },
+
+	{ KERN_SHMLOCKED,		"shm_locked" },
 	{}
 };
Signature · 1 line
1.5.4.1