Re: stalled MM patches

[Vinayak Menon <vinmenon@codeaurora.org>]

On 12/1/2017 3:44 AM, Andrew Morton wrote:
> I'm sitting on a bunch of patches of varying ages which are stuck for
> various reason.  Can people please take a look some time and assist
> with getting them merged, dropped or fixed?
>
> I'll send them all out in a sec.  I have rough notes (which might be
> obsolete) and additional details can be found by following the Link: in
> the individual patches.
>
> Thanks.
>
> Subject: mm: skip HWPoisoned pages when onlining pages
>
>   mhocko had issues with this one.
>
> Subject: mm/mempolicy: remove redundant check in get_nodes
> Subject: mm/mempolicy: fix the check of nodemask from user
> Subject: mm/mempolicy: add nodes_empty check in SYSC_migrate_pages
>
>   Three patch series.  Stuck because vbabka wasn't happy with #3.
>
> Subject: mm: memcontrol: eliminate raw access to stat and event counters
> Subject: mm: memcontrol: implement lruvec stat functions on top of each other
> Subject: mm: memcontrol: fix excessive complexity in memory.stat reporting
>
>   Three patch series.  Stuck because #3 caused fengguang-bot to
>   report "BUG: using __this_cpu_xchg() in preemptible"
>
> Subject: mm/madvise: enable soft offline of HugeTLB pages at PUD level
>
>   Hoping for Kirill review.  I wanted additional code comments (I
>   think).  mhocko nacked it.
>
> Subject: mm: readahead: increase maximum readahead window
>
>   Darrick said he was going to do some testing.
>
> Subject: fs/proc/task_mmu.c: do not show VmExe bigger than total executable virtual memory
>
>   I had some questions, but they were responded to, whcih made my
>   head spin a bit.  I guess I'll push this to Linus but would
>   appreciate additional review.
>
> Subject: mm, hugetlb: remove hugepages_treat_as_movable sysctl
>
>   I'm holding this for additional testing.  I guess I'll merge it in
>   4.16-rc1.
>
> Subject: mm: vmscan: do not pass reclaimed slab to vmpressure
>
>   mhocko asked for a changelog update
>
Michal was of the opinion that we should reconsider how we calculate vmpressure rather than
making this fix. I am okay if this patch is dropped, but I feel it would be better if slab reclaimed
pages are skipped from vmpressure calculation because
1) Adding only reclaimed pages to a model which works on scanned and reclaimed seems like
a wrong thing.
2) As Minchan mentioned, the cost model is different and thus adding slab reclaimed would not
be a right thing to do.

But Michal's question was whether the model would be better if we skip slab reclaimed pages.
I am not sure about this, but at least vmpressure without slab noise gives the pressure on LRU
and we have been using this in deciding the right point to trigger lowmemorykiller kills. And we
have seen that slab noise make the vmpressure value unreliable at least for lowmemorykiller.
But I agree this is just one workload, so I don't have more points in favor of this patch.

Thanks,
Vinayak

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