From: Michal Hocko <mhocko@kernel.org>
To: David Hildenbrand <david@redhat.com>
Cc: Shile Zhang <shile.zhang@linux.alibaba.com>,
Andrew Morton <akpm@linux-foundation.org>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] mm: fix tick timer stall during deferred page init
Date: Wed, 1 Apr 2020 18:00:48 +0200 [thread overview]
Message-ID: <20200401160048.GU22681@dhcp22.suse.cz> (raw)
In-Reply-To: <dfc0014a-9b85-5eeb-70ea-d622ccf5d988@redhat.com>
On Wed 01-04-20 17:50:22, David Hildenbrand wrote:
> On 01.04.20 17:42, Michal Hocko wrote:
> > I am sorry but I have completely missed this patch.
> >
> > On Wed 11-03-20 20:38:48, Shile Zhang wrote:
> >> When 'CONFIG_DEFERRED_STRUCT_PAGE_INIT' is set, 'pgdatinit' kthread will
> >> initialise the deferred pages with local interrupts disabled. It is
> >> introduced by commit 3a2d7fa8a3d5 ("mm: disable interrupts while
> >> initializing deferred pages").
> >>
> >> On machine with NCPUS <= 2, the 'pgdatinit' kthread could be bound to
> >> the boot CPU, which could caused the tick timer long time stall, system
> >> jiffies not be updated in time.
> >>
> >> The dmesg shown that:
> >>
> >> [ 0.197975] node 0 initialised, 32170688 pages in 1ms
> >>
> >> Obviously, 1ms is unreasonable.
> >>
> >> Now, fix it by restore in the pending interrupts for every 32*1204 pages
> >> (128MB) initialized, give the chance to update the systemd jiffies.
> >> The reasonable demsg shown likes:
> >>
> >> [ 1.069306] node 0 initialised, 32203456 pages in 894ms
> >>
> >> Fixes: 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages").
> >
> > I dislike this solution TBH. It effectivelly conserves the current code
> > and just works around the problem. Why do we hold the IRQ lock here in
> > the first place? This is an early init code and a very limited code is
> > running at this stage. Certainly nothing memory hotplug related which
> > should be the only path really interested in the resize lock AFAIR.
>
> Yeah, I don't think ACPI and friends are up yet.
Just to save somebody time to check. The deferred initialization blocks
the further boot until all workders are done - see page_alloc_init_late
(kernel_init path).
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-04-01 16:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-11 12:38 [PATCH v3] mm: fix tick timer stall during deferred page init Shile Zhang
2020-03-11 17:45 ` Pavel Tatashin
2020-03-11 20:16 ` Kirill Tkhai
2020-03-11 20:25 ` Pavel Tatashin
2020-03-19 19:05 ` Daniel Jordan
2020-03-26 18:58 ` Daniel Jordan
2020-03-26 19:36 ` Pavel Tatashin
2020-03-27 4:39 ` Shile Zhang
2020-03-28 0:17 ` Daniel Jordan
2020-04-01 14:26 ` David Hildenbrand
2020-04-01 15:42 ` Michal Hocko
2020-04-01 15:50 ` David Hildenbrand
2020-04-01 16:00 ` Michal Hocko [this message]
2020-04-01 16:09 ` Daniel Jordan
2020-04-01 16:12 ` Michal Hocko
2020-04-01 16:15 ` David Hildenbrand
2020-04-01 16:18 ` Daniel Jordan
2020-04-01 16:26 ` Michal Hocko
2020-04-01 16:41 ` Pavel Tatashin
2020-04-01 16:46 ` Michal Hocko
2020-04-01 16:51 ` Pavel Tatashin
2020-04-01 17:13 ` Daniel Jordan
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