On Sun, 13 Apr 2014 20:05:34 +0200 Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> wrote: > Hi Andrew, > > On 04/02/2014 12:08 AM, Andrew Morton wrote: > > Well, I'm assuming 64GB==infinity. It *was* infinity in the RHEL5 > > timeframe, but infinity has since become larger so pickanumber. > > I think infinity is the right solution: > The only common case where infinity is wrong would be Android - and > Android disables sysv shm entirely. > > There are two patches: > http://marc.info/?l=linux-kernel&m=139730332306185&q=raw > http://marc.info/?l=linux-kernel&m=139727299800644&q=raw > > Could you apply one of them? > I wrote the first one, thus I'm biased which one is better. I like your patch because applying it might encourage you to send more kernel patches - I miss the old days ;) But I do worry about disrupting existing systems so I like Davidlohr's idea of making the change a no-op for people who are currently explicitly setting shmmax and shmall. In an ideal world, system administrators would review this change, would remove their explicit limit-setting and would retest everything then roll it out. But in the real world with Davidlohr's patch, they just won't know that we did this and they'll still be manually configuring shmmax/shmall ten years from now. I almost wonder if we should drop a printk_once("hey, you don't need to do that any more") when shmmax/shmall are altered? I think the changelogs for both patches could afford to spend much more time talking about *why* we're making this change. What problem is the current code causing? This is a somewhat risky change and we should demonstrate good reasons for making it. If people end up taking damage because of this change, they are going to be looking at that changelog trying to work out why we did this to them, so let's explain it carefully. -- 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>