linux/ipc
Manfred Spraul 0050ee059f ipc/msg: increase MSGMNI, remove scaling
SysV can be abused to allocate 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 the logic can be removed.

The code preserves auto_msgmni to avoid breaking any user space applications
that expect that the value exists.

Notes:
1) 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 by Android).

2) MSGMAX and MSGMNB are intentionally not increased, as these values are used
to control latency vs. throughput:
If MSGMNB is large, then msgsnd() just returns and more messages can be queued
before a task switch to a task that calls msgrcv() is forced.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-13 12:42:52 -08:00
..
compat_mq.c ipc, kernel: use Linux headers 2014-06-06 16:08:14 -07:00
compat.c ipc: resolve shadow warnings 2014-10-14 02:18:23 +02:00
ipc_sysctl.c ipc/msg: increase MSGMNI, remove scaling 2014-12-13 12:42:52 -08:00
Makefile ipc/msg: increase MSGMNI, remove scaling 2014-12-13 12:42:52 -08:00
mq_sysctl.c ipc: convert use of typedef ctl_table to struct ctl_table 2014-06-06 16:08:16 -07:00
mqueue.c new helper: audit_file() 2014-11-19 13:01:26 -05:00
msg.c ipc/msg: increase MSGMNI, remove scaling 2014-12-13 12:42:52 -08:00
msgutil.c
namespace.c ipc/msg: increase MSGMNI, remove scaling 2014-12-13 12:42:52 -08:00
sem.c ipc/sem.c: change memory barrier in sem_lock() to smp_rmb() 2014-12-13 12:42:52 -08:00
shm.c ipc/shm: kill the historical/wrong mm->start_stack check 2014-10-14 02:18:23 +02:00
syscall.c
util.c ipc/msg: increase MSGMNI, remove scaling 2014-12-13 12:42:52 -08:00
util.h ipc, kernel: clear whitespace 2014-06-06 16:08:14 -07:00