path: root/ipc/Makefile
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authorManfred Spraul <manfred@colorfullife.com>2014-12-12 16:58:14 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-13 12:42:52 -0800
commite843e7d2c88b7db107a86bd2c7145dc715c058f4 (patch)
tree01557305cc1446467c9e70ba287f9b0360c9e1ce /ipc/Makefile
parentipc/sem.c: change memory barrier in sem_lock() to smp_rmb() (diff)
ipc/sem.c: increase SEMMSL, SEMMNI, SEMOPM
a) 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 the sysv sem limits so that all known applications will work with these defaults. b) With regards to the maximum supported: Some of the specified hard limits are not correct anymore, therefore the patch updates the documentation. - SEMMNI must stay below IPCMNI, which is 32768. As for SHMMAX: Stay a bit below this limit. - SEMMSL was limited to 8k, to ensure that the kmalloc for the kernel array was limited to 16 kB (order=2) This doesn't apply anymore: - the allocation size isn't sizeof(short)*nsems anymore. - ipc_alloc falls back to vmalloc - SEMOPM should stay below 1000, to limit the kmalloc in semtimedop() to an order=1 allocation. Therefore: Leave it at 500 (order=0 allocation). Note: If an administrator must limit the memory allocations, then he can set the values as necessary. Or he can disable sysv entirely (as e.g. done by Android). Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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