[PATCH 1/3] ipc/msg: increase MSGMNI, remove scaling
From: Manfred Spraul
Date: Thu May 29 2014 - 14:47:47 EST
SysV can be abused to allocated locked kernel memory.
For most systems, a small limit doesn't make sense,
see the discussion with regards to SHMMAX.
Therefore: increase MSGMNI to the maximum supported.
And: if we ignore the risk of locking too much memory, then
an automatic scaling of MSGMNI doesn't make sense.
Therefore: remove the whole logic.
Note:
If an administrator must limit the memory allocations, then
he can set MSGMNI as necessary.
Or he can disable sysv entirely (as e.g. done with Android).
---
include/linux/ipc_namespace.h | 20 ----------
include/uapi/linux/msg.h | 12 +-----
ipc/Makefile | 2 +-
ipc/ipc_sysctl.c | 87 +---------------------------------------
ipc/ipcns_notifier.c | 92 -------------------------------------------
ipc/msg.c | 36 +----------------
ipc/namespace.c | 22 -----------
ipc/util.c | 40 -------------------
8 files changed, 4 insertions(+), 307 deletions(-)
delete mode 100644 ipc/ipcns_notifier.c
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 35e7eca..e365d5e 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -7,15 +7,6 @@
#include <linux/notifier.h>
#include <linux/nsproxy.h>
-/*
- * ipc namespace events
- */
-#define IPCNS_MEMCHANGED 0x00000001 /* Notify lowmem size changed */
-#define IPCNS_CREATED 0x00000002 /* Notify new ipc namespace created */
-#define IPCNS_REMOVED 0x00000003 /* Notify ipc namespace removed */
-
-#define IPCNS_CALLBACK_PRI 0
-
struct user_namespace;
struct ipc_ids {
@@ -38,7 +29,6 @@ struct ipc_namespace {
unsigned int msg_ctlmni;
atomic_t msg_bytes;
atomic_t msg_hdrs;
- int auto_msgmni;
size_t shm_ctlmax;
size_t shm_ctlall;
@@ -77,18 +67,8 @@ extern atomic_t nr_ipc_ns;
extern spinlock_t mq_lock;
#ifdef CONFIG_SYSVIPC
-extern int register_ipcns_notifier(struct ipc_namespace *);
-extern int cond_register_ipcns_notifier(struct ipc_namespace *);
-extern void unregister_ipcns_notifier(struct ipc_namespace *);
-extern int ipcns_notify(unsigned long);
extern void shm_destroy_orphaned(struct ipc_namespace *ns);
#else /* CONFIG_SYSVIPC */
-static inline int register_ipcns_notifier(struct ipc_namespace *ns)
-{ return 0; }
-static inline int cond_register_ipcns_notifier(struct ipc_namespace *ns)
-{ return 0; }
-static inline void unregister_ipcns_notifier(struct ipc_namespace *ns) { }
-static inline int ipcns_notify(unsigned long l) { return 0; }
static inline void shm_destroy_orphaned(struct ipc_namespace *ns) {}
#endif /* CONFIG_SYSVIPC */
diff --git a/include/uapi/linux/msg.h b/include/uapi/linux/msg.h
index a703755..ae9ddd2 100644
--- a/include/uapi/linux/msg.h
+++ b/include/uapi/linux/msg.h
@@ -50,17 +50,7 @@ struct msginfo {
unsigned short msgseg;
};
-/*
- * Scaling factor to compute msgmni:
- * the memory dedicated to msg queues (msgmni * msgmnb) should occupy
- * at most 1/MSG_MEM_SCALE of the lowmem (see the formula in ipc/msg.c):
- * up to 8MB : msgmni = 16 (MSGMNI)
- * 4 GB : msgmni = 8K
- * more than 16 GB : msgmni = 32K (IPCMNI)
- */
-#define MSG_MEM_SCALE 32
-
-#define MSGMNI 16 /* <= IPCMNI */ /* max # of msg queue identifiers */
+#define MSGMNI 32000 /* <= IPCMNI */ /* max # of msg queue identifiers */
#define MSGMAX 8192 /* <= INT_MAX */ /* max size of message (bytes) */
#define MSGMNB 16384 /* <= INT_MAX */ /* default max size of a message queue */
diff --git a/ipc/Makefile b/ipc/Makefile
index 9075e17..86c7300 100644
--- a/ipc/Makefile
+++ b/ipc/Makefile
@@ -3,7 +3,7 @@
#
obj-$(CONFIG_SYSVIPC_COMPAT) += compat.o
-obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.o ipcns_notifier.o syscall.o
+obj-$(CONFIG_SYSVIPC) += util.o msgutil.o msg.o sem.o shm.o syscall.o
obj-$(CONFIG_SYSVIPC_SYSCTL) += ipc_sysctl.o
obj_mq-$(CONFIG_COMPAT) += compat_mq.o
obj-$(CONFIG_POSIX_MQUEUE) += mqueue.o msgutil.o $(obj_mq-y)
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index 998d31b..cc34646 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -62,29 +62,6 @@ static int proc_ipc_dointvec_minmax_orphans(ctl_table *table, int write,
return err;
}
-static int proc_ipc_callback_dointvec_minmax(ctl_table *table, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- struct ctl_table ipc_table;
- size_t lenp_bef = *lenp;
- int rc;
-
- memcpy(&ipc_table, table, sizeof(ipc_table));
- ipc_table.data = get_ipc(table);
-
- rc = proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
-
- if (write && !rc && lenp_bef == *lenp)
- /*
- * Tunable has successfully been changed by hand. Disable its
- * automatic adjustment. This simply requires unregistering
- * the notifiers that trigger recalculation.
- */
- unregister_ipcns_notifier(current->nsproxy->ipc_ns);
-
- return rc;
-}
-
static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
{
@@ -96,64 +73,11 @@ static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
lenp, ppos);
}
-/*
- * Routine that is called when the file "auto_msgmni" has successfully been
- * written.
- * Two values are allowed:
- * 0: unregister msgmni's callback routine from the ipc namespace notifier
- * chain. This means that msgmni won't be recomputed anymore upon memory
- * add/remove or ipc namespace creation/removal.
- * 1: register back the callback routine.
- */
-static void ipc_auto_callback(int val)
-{
- if (!val)
- unregister_ipcns_notifier(current->nsproxy->ipc_ns);
- else {
- /*
- * Re-enable automatic recomputing only if not already
- * enabled.
- */
- recompute_msgmni(current->nsproxy->ipc_ns);
- cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
- }
-}
-
-static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
- void __user *buffer, size_t *lenp, loff_t *ppos)
-{
- struct ctl_table ipc_table;
- size_t lenp_bef = *lenp;
- int oldval;
- int rc;
-
- memcpy(&ipc_table, table, sizeof(ipc_table));
- ipc_table.data = get_ipc(table);
- oldval = *((int *)(ipc_table.data));
-
- rc = proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
-
- if (write && !rc && lenp_bef == *lenp) {
- int newval = *((int *)(ipc_table.data));
- /*
- * The file "auto_msgmni" has correctly been set.
- * React by (un)registering the corresponding tunable, if the
- * value has changed.
- */
- if (newval != oldval)
- ipc_auto_callback(newval);
- }
-
- return rc;
-}
-
#else
#define proc_ipc_doulongvec_minmax NULL
#define proc_ipc_dointvec NULL
#define proc_ipc_dointvec_minmax NULL
#define proc_ipc_dointvec_minmax_orphans NULL
-#define proc_ipc_callback_dointvec_minmax NULL
-#define proc_ipcauto_dointvec_minmax NULL
#endif
static int zero;
@@ -205,7 +129,7 @@ static struct ctl_table ipc_kern_table[] = {
.data = &init_ipc_ns.msg_ctlmni,
.maxlen = sizeof(init_ipc_ns.msg_ctlmni),
.mode = 0644,
- .proc_handler = proc_ipc_callback_dointvec_minmax,
+ .proc_handler = proc_ipc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &int_max,
},
@@ -225,15 +149,6 @@ static struct ctl_table ipc_kern_table[] = {
.mode = 0644,
.proc_handler = proc_ipc_dointvec,
},
- {
- .procname = "auto_msgmni",
- .data = &init_ipc_ns.auto_msgmni,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_ipcauto_dointvec_minmax,
- .extra1 = &zero,
- .extra2 = &one,
- },
#ifdef CONFIG_CHECKPOINT_RESTORE
{
.procname = "sem_next_id",
diff --git a/ipc/ipcns_notifier.c b/ipc/ipcns_notifier.c
deleted file mode 100644
index b9b31a4..0000000
--- a/ipc/ipcns_notifier.c
+++ /dev/null
@@ -1,92 +0,0 @@
-/*
- * linux/ipc/ipcns_notifier.c
- * Copyright (C) 2007 BULL SA. Nadia Derbey
- *
- * Notification mechanism for ipc namespaces:
- * The callback routine registered in the memory chain invokes the ipcns
- * notifier chain with the IPCNS_MEMCHANGED event.
- * Each callback routine registered in the ipcns namespace recomputes msgmni
- * for the owning namespace.
- */
-
-#include <linux/msg.h>
-#include <linux/rcupdate.h>
-#include <linux/notifier.h>
-#include <linux/nsproxy.h>
-#include <linux/ipc_namespace.h>
-
-#include "util.h"
-
-
-
-static BLOCKING_NOTIFIER_HEAD(ipcns_chain);
-
-
-static int ipcns_callback(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- struct ipc_namespace *ns;
-
- switch (action) {
- case IPCNS_MEMCHANGED: /* amount of lowmem has changed */
- case IPCNS_CREATED:
- case IPCNS_REMOVED:
- /*
- * It's time to recompute msgmni
- */
- ns = container_of(self, struct ipc_namespace, ipcns_nb);
- /*
- * No need to get a reference on the ns: the 1st job of
- * free_ipc_ns() is to unregister the callback routine.
- * blocking_notifier_chain_unregister takes the wr lock to do
- * it.
- * When this callback routine is called the rd lock is held by
- * blocking_notifier_call_chain.
- * So the ipc ns cannot be freed while we are here.
- */
- recompute_msgmni(ns);
- break;
- default:
- break;
- }
-
- return NOTIFY_OK;
-}
-
-int register_ipcns_notifier(struct ipc_namespace *ns)
-{
- int rc;
-
- memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
- ns->ipcns_nb.notifier_call = ipcns_callback;
- ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
- rc = blocking_notifier_chain_register(&ipcns_chain, &ns->ipcns_nb);
- if (!rc)
- ns->auto_msgmni = 1;
- return rc;
-}
-
-int cond_register_ipcns_notifier(struct ipc_namespace *ns)
-{
- int rc;
-
- memset(&ns->ipcns_nb, 0, sizeof(ns->ipcns_nb));
- ns->ipcns_nb.notifier_call = ipcns_callback;
- ns->ipcns_nb.priority = IPCNS_CALLBACK_PRI;
- rc = blocking_notifier_chain_cond_register(&ipcns_chain,
- &ns->ipcns_nb);
- if (!rc)
- ns->auto_msgmni = 1;
- return rc;
-}
-
-void unregister_ipcns_notifier(struct ipc_namespace *ns)
-{
- blocking_notifier_chain_unregister(&ipcns_chain, &ns->ipcns_nb);
- ns->auto_msgmni = 0;
-}
-
-int ipcns_notify(unsigned long val)
-{
- return blocking_notifier_call_chain(&ipcns_chain, val, NULL);
-}
diff --git a/ipc/msg.c b/ipc/msg.c
index 6498531..ea7e0d1 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -76,43 +76,12 @@ static int newque(struct ipc_namespace *, struct ipc_params *);
static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
#endif
-/*
- * Scale msgmni with the available lowmem size: the memory dedicated to msg
- * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
- * Also take into account the number of nsproxies created so far.
- * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
- */
-void recompute_msgmni(struct ipc_namespace *ns)
-{
- struct sysinfo i;
- unsigned long allowed;
- int nb_ns;
-
- si_meminfo(&i);
- allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
- / MSGMNB;
- nb_ns = atomic_read(&nr_ipc_ns);
- allowed /= nb_ns;
-
- if (allowed < MSGMNI) {
- ns->msg_ctlmni = MSGMNI;
- return;
- }
-
- if (allowed > IPCMNI / nb_ns) {
- ns->msg_ctlmni = IPCMNI / nb_ns;
- return;
- }
-
- ns->msg_ctlmni = allowed;
-}
void msg_init_ns(struct ipc_namespace *ns)
{
ns->msg_ctlmax = MSGMAX;
ns->msg_ctlmnb = MSGMNB;
-
- recompute_msgmni(ns);
+ ns->msg_ctlmni = MSGMNI;
atomic_set(&ns->msg_bytes, 0);
atomic_set(&ns->msg_hdrs, 0);
@@ -131,9 +100,6 @@ void __init msg_init(void)
{
msg_init_ns(&init_ipc_ns);
- printk(KERN_INFO "msgmni has been set to %d\n",
- init_ipc_ns.msg_ctlmni);
-
ipc_init_proc_interface("sysvipc/msg",
" key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
IPC_MSG_IDS, sysvipc_msg_proc_show);
diff --git a/ipc/namespace.c b/ipc/namespace.c
index 59451c1..6c01c2a 100644
--- a/ipc/namespace.c
+++ b/ipc/namespace.c
@@ -45,14 +45,6 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
msg_init_ns(ns);
shm_init_ns(ns);
- /*
- * msgmni has already been computed for the new ipc ns.
- * Thus, do the ipcns creation notification before registering that
- * new ipcns in the chain.
- */
- ipcns_notify(IPCNS_CREATED);
- register_ipcns_notifier(ns);
-
ns->user_ns = get_user_ns(user_ns);
return ns;
@@ -99,25 +91,11 @@ void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
static void free_ipc_ns(struct ipc_namespace *ns)
{
- /*
- * Unregistering the hotplug notifier at the beginning guarantees
- * that the ipc namespace won't be freed while we are inside the
- * callback routine. Since the blocking_notifier_chain_XXX routines
- * hold a rw lock on the notifier list, unregister_ipcns_notifier()
- * won't take the rw lock before blocking_notifier_call_chain() has
- * released the rd lock.
- */
- unregister_ipcns_notifier(ns);
sem_exit_ns(ns);
msg_exit_ns(ns);
shm_exit_ns(ns);
atomic_dec(&nr_ipc_ns);
- /*
- * Do the ipcns removal notification after decrementing nr_ipc_ns in
- * order to have a correct value when recomputing msgmni.
- */
- ipcns_notify(IPCNS_REMOVED);
put_user_ns(ns->user_ns);
proc_free_inum(ns->proc_inum);
kfree(ns);
diff --git a/ipc/util.c b/ipc/util.c
index 2eb0d1e..768e1fc75 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -71,44 +71,6 @@ struct ipc_proc_iface {
int (*show)(struct seq_file *, void *);
};
-static void ipc_memory_notifier(struct work_struct *work)
-{
- ipcns_notify(IPCNS_MEMCHANGED);
-}
-
-static int ipc_memory_callback(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
-
- switch (action) {
- case MEM_ONLINE: /* memory successfully brought online */
- case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
- /*
- * This is done by invoking the ipcns notifier chain with the
- * IPC_MEMCHANGED event.
- * In order not to keep the lock on the hotplug memory chain
- * for too long, queue a work item that will, when waken up,
- * activate the ipcns notification chain.
- */
- schedule_work(&ipc_memory_wq);
- break;
- case MEM_GOING_ONLINE:
- case MEM_GOING_OFFLINE:
- case MEM_CANCEL_ONLINE:
- case MEM_CANCEL_OFFLINE:
- default:
- break;
- }
-
- return NOTIFY_OK;
-}
-
-static struct notifier_block ipc_memory_nb = {
- .notifier_call = ipc_memory_callback,
- .priority = IPC_CALLBACK_PRI,
-};
-
/**
* ipc_init - initialise ipc subsystem
*
@@ -124,8 +86,6 @@ static int __init ipc_init(void)
sem_init();
msg_init();
shm_init();
- register_hotmemory_notifier(&ipc_memory_nb);
- register_ipcns_notifier(&init_ipc_ns);
return 0;
}
device_initcall(ipc_init);
--
1.9.3
--
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