linux-kernel - Re: [RFC PATCH] mm: memory-failure: add soft-offline stat in mf

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Message-ID: <CACw3F51TiRZJMkze-u3a3E_3w65=PMhEUBaBQLUgNwRNuY6+3w@mail.gmail.com>
Date: Tue, 26 Nov 2024 23:06:51 -0800
From: Jiaqi Yan <jiaqiyan@...gle.com>
To: "Tomohiro Misono (Fujitsu)" <misono.tomohiro@...itsu.com>
Cc: Miaohe Lin <linmiaohe@...wei.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	Naoya Horiguchi <nao.horiguchi@...il.com>
Subject: Re: [RFC PATCH] mm: memory-failure: add soft-offline stat in mf_stats

On Tue, Nov 26, 2024 at 6:32 PM Tomohiro Misono (Fujitsu)
<misono.tomohiro@...itsu.com> wrote:
>
> > On 2024/11/21 12:55, Tomohiro Misono wrote:
> > > commit 44b8f8bf2438 ("mm: memory-failure: add memory failure stats
> >
> > Sorry for late, I've been swamped recently.
>
> Hi,
> Thanks for your comments.
>
> >
> > > to sysfs") introduces per NUMA memory error stats which show
> > > breakdown of HardwareCorrupted of /proc/meminfo in
> > > /sys/devices/system/node/nodeX/memory_failure.
> >
> > Thanks for your patch.
> >
> > >
> > > However, HardwareCorrupted also counts soft-offline pages. So, add
> > > soft-offline stats in mf_stats too to represent more accurate status.
> >
> > Adding soft-offline stats makes sense to me.
>
> Thanks for confirming.

Agreed with Miaohe.

>
> >
> > >
> > > This updates total count as:
> > >   total = recovered + ignored + failed + delayed + soft_offline>
> > > Test example:
> > > 1) # grep HardwareCorrupted /proc/meminfo
> > >      HardwareCorrupted:     0 kB
> > > 2) soft-offline 1 page by madvise(MADV_SOFT_OFFLINE)
> > > 3) # grep HardwareCorrupted /proc/meminfo
> > >      HardwareCorrupted:     4 kB
> > >    # grep -r "" /sys/devices/system/node/node0/memory_failure
> > >    /sys/devices/system/node/node0/memory_failure/total:1
> > >    /sys/devices/system/node/node0/memory_failure/soft_offline:1
> > >    /sys/devices/system/node/node0/memory_failure/recovered:0
> > >    /sys/devices/system/node/node0/memory_failure/ignored:0
> > >    /sys/devices/system/node/node0/memory_failure/failed:0
> > >    /sys/devices/system/node/node0/memory_failure/delayed:0
> > >
> > > Signed-off-by: Tomohiro Misono <misono.tomohiro@...itsu.com>
> > > ---
> > > Hello
> > >
> > > This is RFC because I'm not sure adding SOFT_OFFLINE in enum
> > > mf_result is a right approach. Also, maybe is it better to move
> > > update_per_node_mf_stats() into num_poisoned_pages_inc()?
> > >
> > > I omitted some cleanups and sysfs doc update in this version to
> > > highlight changes. I'd appreciate any suggestions.
> > >
> > > Regards,
> > > Tomohiro Misono
> > >
> > >  include/linux/mm.h     | 2 ++
> > >  include/linux/mmzone.h | 4 +++-
> > >  mm/memory-failure.c    | 9 +++++++++
> > >  3 files changed, 14 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > > index 5d6cd523c7c0..7f93f6883760 100644
> > > --- a/include/linux/mm.h
> > > +++ b/include/linux/mm.h
> > > @@ -3991,6 +3991,8 @@ enum mf_result {
> > >     MF_FAILED,      /* Error: handling failed */
> > >     MF_DELAYED,     /* Will be handled later */
> > >     MF_RECOVERED,   /* Successfully recovered */
> > > +
> > > +   MF_RES_SOFT_OFFLINE, /* Soft-offline */
> >
> > It might not be a good idea to add MF_RES_SOFT_OFFLINE here. 'mf_result' is used to record
> > the result of memory failure handler. So it might be inappropriate to add MF_RES_SOFT_OFFLINE here.
>
> Understood. As I don't see other suitable place to put ENUM value, how about changing like below?
> Or, do you prefer adding another ENUM type instead of this?

I think SOFT_OFFLINE-ed is one of the results of successfully
recovered, and the other one is HARD_OFFLINE-ed. So how about make a
separate sub-ENUM for MF_RECOVERED? Something like:

enum mf_recovered_result {
  MF_RECOVERED_SOFT_OFFLINE,
  MF_RECOVERED_HARD_OFFLINE,
};

And
1. total = recovered + ignored + failed + delayed
2. recovered = soft_offline + hard_offline

>
> ```
> static void update_per_node_mf_stats(unsigned long pfn,
> -                                    enum mf_result result)
> +                                    enum mf_result result, bool is_soft_offline)
>  {
>         int nid = MAX_NUMNODES;
>         struct memory_failure_stats *mf_stats = NULL;
> @@ -1299,6 +1299,12 @@ static void update_per_node_mf_stats(unsigned long pfn,
>         }
>
>         mf_stats = &NODE_DATA(nid)->mf_stats;
> +       if (is_soft_offline) {
> +               ++mf->stats->soft_offlined;
> +               ++mf_stats->total;
> +               return;
> +       }
> +
>         switch (result) {
>         case MF_IGNORED:
>                 ++mf_stats->ignored;
> ```
>
> Regards,
> Tomohiro Misono
>
> >
> >
> > Thanks.
> > .
>