On Mon, 31 Mar 2014 16:25:32 -0700 Davidlohr Bueso <davidlohr@xxxxxx> wrote: > On Mon, 2014-03-31 at 16:13 -0700, Andrew Morton wrote: > > On Mon, 31 Mar 2014 15:59:33 -0700 Davidlohr Bueso <davidlohr@xxxxxx> wrote: > > > > > > > > > > - Shouldn't there be a way to alter this namespace's shm_ctlmax? > > > > > > Unfortunately this would also add the complexity I previously mentioned. > > > > But if the current namespace's shm_ctlmax is too small, you're screwed. > > Have to shut down the namespace all the way back to init_ns and start > > again. > > > > > > - What happens if we just nuke the limit altogether and fall back to > > > > the next check, which presumably is the rlimit bounds? > > > > > > afaik we only have rlimit for msgqueues. But in any case, while I like > > > that simplicity, it's too late. Too many workloads (specially DBs) rely > > > heavily on shmmax. Removing it and relying on something else would thus > > > cause a lot of things to break. > > > > It would permit larger shm segments - how could that break things? It > > would make most or all of these issues go away? > > > > So sysadmins wouldn't be very happy, per man shmget(2): > > EINVAL A new segment was to be created and size < SHMMIN or size > > SHMMAX, or no new segment was to be created, a segment with given key > existed, but size is greater than the size of that segment. So their system will act as if they had set SHMMAX=enormous. What problems could that cause? Look. The 32M thing is causing problems. Arbitrarily increasing the arbitrary 32M to an arbitrary 128M won't fix anything - we still have the problem. Think bigger, please: how can we make this problem go away for ever? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>