Bug#695182: [RFC] Reproducible OOM with partial workaround
On Fri, 2013-01-11 at 00:01 -0800, Andrew Morton wrote:
> On Fri, 11 Jan 2013 12:46:15 +1100 paul.szabo@sydney.edu.au wrote:
>
> > > ... I don't believe 64GB of RAM has _ever_ been booted on a 32-bit
> > > kernel without either violating the ABI (3GB/1GB split) or doing
> > > something that never got merged upstream ...
> >
> > Sorry to be so contradictory:
> >
> > psz@como:~$ uname -a
> > Linux como.maths.usyd.edu.au 3.2.32-pk06.10-t01-i386 #1 SMP Sat Jan 5 18:34:25 EST 2013 i686 GNU/Linux
> > psz@como:~$ free -l
> > total used free shared buffers cached
> > Mem: 64446900 4729292 59717608 0 15972 480520
> > Low: 375836 304400 71436
> > High: 64071064 4424892 59646172
> > -/+ buffers/cache: 4232800 60214100
> > Swap: 134217724 0 134217724
> > psz@como:~$
> >
> > (though I would not know about violations).
> >
> > But OK, I take your point that I should move with the times.
>
> Check /proc/slabinfo, see if all your lowmem got eaten up by buffer_heads.
>
> If so, you *may* be able to work around this by setting
> /proc/sys/vm/dirty_ratio really low, so the system keeps a minimum
> amount of dirty pagecache around. Then, with luck, if we haven't
> broken the buffer_heads_over_limit logic it in the past decade (we
> probably have), the VM should be able to reclaim those buffer_heads.
>
> Alternatively, use a filesystem which doesn't attach buffer_heads to
> dirty pages. xfs or btrfs, perhaps.
>
Hi Andrew,
What's the meaning of attaching buffer_heads to dirty pages?
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