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

From: William Lee Irwin III (wli_at_holomorphy.com)
Date: 11/26/03

  • Next message: Christian Schlittchen: "2.6.0-test10: Badness in local_bh_enable at kernel/softirq.c:121" 
    Date:	Wed, 26 Nov 2003 02:39:57 -0800
To: Ihar 'Philips' Filipau <filia@softhome.net>

    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
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