ipc: introduce shm_rmid_forced sysctl
PATCH 36/64 ipc: introduce shm_rmid_forced sysctl
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Subject: [patch 36/64] ipc: introduce shm_rmid_forced sysctl
To: [email protected]
Cc: [email protected], [email protected], [email protected],
[email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
From: [email protected]
Date: Tue, 26 Jul 2011 16:08:48 -0700
From: Vasiliy Kulikov <[email protected]>
Add support for the shm_rmid_forced sysctl. If set to 1, all shared memory objects in current ipc namespace will be automatically forced to use IPC_RMID.
The POSIX way of handling shmem allows one to create shm objects and call shmdt(), leaving shm object associated with no process, thus consuming memory not counted via rlimits.
With shm_rmid_forced=1 the shared memory object is counted at least for one process, so OOM killer may effectively kill the fat process holding the shared memory.
It obviously breaks POSIX - some programs relying on the feature would stop working. So set shm_rmid_forced=1 only if you're sure nobody uses "orphaned" memory. Use shm_rmid_forced=0 by default for compatability reasons.
The feature was previously impemented in -ow as a configure option.
[[email protected]: fix documentation, per Randy]
[[email protected]: fix warning]
[[email protected]: readability/conventionality tweaks]
[[email protected]: fix shm_rmid_forced/shm_forced_rmid confusion, use standard comment layout]
Signed-off-by Vasiliy Kulikov <[email protected]>
Cc Randy Dunlap <[email protected]>
Cc "Eric W. Biederman" <[email protected]>
Cc "Serge E. Hallyn" <[email protected]>
Cc Daniel Lezcano <[email protected]>
Cc Oleg Nesterov <[email protected]>
Cc Tejun Heo <[email protected]>
Cc Ingo Molnar <[email protected]>
Cc Alan Cox <[email protected]>
Cc Solar Designer <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
---
Documentation/sysctl/kernel.txt | 22 ++++++ include/linux/ipc_namespace.h | 7 ++ include/linux/shm.h | 4 + ipc/ipc_sysctl.c | 36 +++++++++++ ipc/shm.c | 97 ++++++++++++++++++++++++++++-- kernel/exit.c | 1 6 files changed, 163 insertions(+), 4 deletions(-)
Documentation/sysctl/kernel.txt renamed from Documentation/sysctl/kernel.txt~ipc-introduce-shm_rmid_forced-sysctl +22 -0
@@ -61,6 +61,7 @@ show up in /proc/sys/kernel: - rtsig-nr - sem - sg-big-buff [ generic SCSI device (sg) ] +- shm_rmid_forced - shmall - shmmax [ sysv ipc ] - shmmni
@@ -518,6 +519,27 @@ kernel. This value defaults to SHMMAX. ============================================================== +shm_rmid_forced: + +Linux lets you set resource limits, including how much memory one +process can consume, via setrlimit(2). Unfortunately, shared memory +segments are allowed to exist without association with any process, and +thus might not be counted against any resource limits. If enabled, +shared memory segments are automatically destroyed when their attach +count becomes zero after a detach or a process termination. It will +also destroy segments that were created, but never attached to, on exit +from the process. The only use left for IPC_RMID is to immediately +destroy an unattached segment. Of course, this breaks the way things are +defined, so some applications might stop working. Note that this +feature will do you no good unless you also configure your resource +limits (in particular, RLIMIT_AS and RLIMIT_NPROC). Most systems don't +need this. + +Note that if you change this from 0 to 1, already created segments +without users and with a dead originative process will be destroyed. + +============================================================== + softlockup_thresh: This value can be used to lower the softlockup tolerance threshold. The
include/linux/ipc_namespace.h renamed from include/linux/ipc_namespace.h~ipc-introduce-shm_rmid_forced-sysctl +7 -0
@@ -44,6 +44,11 @@ struct ipc_namespace {size_t shm_ctlall;int shm_ctlmni;int shm_tot; +/* +* Defines whether IPC_RMID is forced for _all_ shm segments regardless +* of shmctl() +*/ +int shm_rmid_forced;struct notifier_block ipcns_nb;
@@ -72,6 +77,7 @@ extern int register_ipcns_notifier(strucextern 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 ; }
@@ -79,6 +85,7 @@ static inline int cond_register_ipcns_no {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 */ #ifdef CONFIG_POSIX_MQUEUE
include/linux/shm.h renamed from include/linux/shm.h~ipc-introduce-shm_rmid_forced-sysctl +4 -0
@@ -106,6 +106,7 @@ struct shmid_kernel /* private to the ke#ifdef CONFIG_SYSVIPC long do_shmat (int shmid,char __user *shmaddr,int shmflg,unsigned long *addr);extern int is_file_shm_hugepages (struct file *file); +extern void exit_shm (struct task_struct *task);#else static inline long do_shmat (int shmid,char __user *shmaddr,int shmflg,unsigned long *addr)
@@ -116,6 +117,9 @@ static inline int is_file_shm_hugepages( {return 0 ; } +static inline void exit_shm (struct task_struct *task) +{ +}#endif #endif /* __KERNEL__ */
ipc/ipc_sysctl.c renamed from ipc/ipc_sysctl.c~ipc-introduce-shm_rmid_forced-sysctl +36 -0
@@ -31,12 +31,37 @@ static int proc_ipc_dointvec(ctl_table * void __user *buffer, size_t *lenp, loff_t *ppos) { struct ctl_table ipc_table; +memcpy (&ipc_table, table,sizeof (ipc_table)); ipc_table.data =get_ipc (table);return proc_dointvec (&ipc_table, write, buffer, lenp, ppos); } +static int proc_ipc_dointvec_minmax (ctl_table *table,int write, +void __user *buffer,size_t *lenp,loff_t *ppos) +{ +struct ctl_table ipc_table; + +memcpy (&ipc_table, table,sizeof (ipc_table)); + ipc_table.data =get_ipc (table); + +return proc_dointvec_minmax (&ipc_table, write, buffer, lenp, ppos); +} + +static int proc_ipc_dointvec_minmax_orphans (ctl_table *table,int write, +void __user *buffer,size_t *lenp,loff_t *ppos) +{ +struct ipc_namespace *ns = current->nsproxy->ipc_ns; +int err =proc_ipc_dointvec_minmax (table, write, buffer, lenp, ppos); + +if (err <0 ) +return err; +if (ns->shm_rmid_forced) +shm_destroy_orphaned (ns); +return err; +} +static int proc_ipc_callback_dointvec (ctl_table *table,int write,void __user *buffer,size_t *lenp,loff_t *ppos) {
@@ -125,6 +150,8 @@ static int proc_ipcauto_dointvec_minmax(#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 NULL#define proc_ipcauto_dointvec_minmax NULL#endif
@@ -155,6 +182,15 @@ static struct ctl_table ipc_kern_table[] .proc_handler = proc_ipc_dointvec, }, { + .procname = "shm_rmid_forced", + .data = &init_ipc_ns.shm_rmid_forced, + .maxlen = sizeof(init_ipc_ns.shm_rmid_forced), + .mode = 0644, + .proc_handler = proc_ipc_dointvec_minmax_orphans, + .extra1 = &zero, + .extra2 = &one, + }, + { .procname = "msgmax", .data = &init_ipc_ns.msg_ctlmax, .maxlen = sizeof (init_ipc_ns.msg_ctlmax),
ipc/shm.c renamed from ipc/shm.c~ipc-introduce-shm_rmid_forced-sysctl +93 -4
124 lines not on this page · raw message
kernel/exit.c renamed from kernel/exit.c~ipc-introduce-shm_rmid_forced-sysctl +1 -0
@@ -980,6 +980,7 @@ NORET_TYPE void do_exit(long code)trace_sched_process_exit (tsk);exit_sem (tsk); +exit_shm (tsk);exit_files (tsk);exit_fs (tsk);check_stack_usage ();
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