Re: 2.2/2.4/2.6 VMs: do malloc() ever return NULL?

William Lee Irwin III
2003-11-26T10:40:07Z

Rik van Riel wrote:
>> Strict non-overcommit mode. You can allocate as much
>> non-file-backed virtual memory as will fit in swap,
>> plus /proc/sys/vm/overcommit_percentage worth of memory.

On Wed, Nov 26, 2003 at 11:30:23AM +0100, Ihar 'Philips' Filipau wrote:
> [ s/overcommit_percentage/overcommit_ratio/ ]
> Thanks! On 2.6 it works as expected. Test with two concurrent memory
> allocations took some time, but both apps stops exactly when memory was
> depleted. Great.
> Did rmap has something todo with this?
> As I see from implementation of do_mmap_pgoff() - it changed from 2.4
> to 2.6 - but there are a lot of common things.
> If I will do dumb back port of this check to 2.4 - do you think it
> will work? 2.4->2.6 memory accounting changed?
> I didn't found this check in your rmap patches for 2.4.22. (btw
> thanks for keeping them up-to-date).

In principle, non-overcommit shouldn't be dependent on rmap, as it
largely consists of keeping track of the sum of MAP_PRIVATE virtual
mappings' sizes and refusing them when they exceed RAM + swap.

-- wli