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authorVasiliy Kulikov <segoon@openwall.com>2011-07-26 19:08:48 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-26 19:49:44 -0400
commitb34a6b1da371ed8af1221459a18c67970f7e3d53 (patch)
tree5addc850de13623b172395b9d0d7d670930fa6b3 /kernel
parentd40dcdb0172a1ba853464983a059fb45e0aaf61a (diff)
ipc: introduce shm_rmid_forced sysctl
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. [akpm@linux-foundation.org: fix documentation, per Randy] [akpm@linux-foundation.org: fix warning] [akpm@linux-foundation.org: readability/conventionality tweaks] [akpm@linux-foundation.org: fix shm_rmid_forced/shm_forced_rmid confusion, use standard comment layout] Signed-off-by: Vasiliy Kulikov <segoon@openwall.com> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: "Serge E. Hallyn" <serge.hallyn@canonical.com> Cc: Daniel Lezcano <daniel.lezcano@free.fr> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Solar Designer <solar@openwall.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/exit.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 9ee58bb9e60f..2913b3509d42 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -980,6 +980,7 @@ NORET_TYPE void do_exit(long code)
980 trace_sched_process_exit(tsk); 980 trace_sched_process_exit(tsk);
981 981
982 exit_sem(tsk); 982 exit_sem(tsk);
983 exit_shm(tsk);
983 exit_files(tsk); 984 exit_files(tsk);
984 exit_fs(tsk); 985 exit_fs(tsk);
985 check_stack_usage(); 986 check_stack_usage();