From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: David Hildenbrand <david@redhat.com>, linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Richard Fontana <rfontana@redhat.com>,
linux-mm@kvack.org, Paul Mackerras <paulus@samba.org>,
Arun KS <arunks@codeaurora.org>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2] powerpc/pseries/cmm: fix managed page counts when migrating pages between zones
Date: Wed, 18 Dec 2019 15:05:11 +1100 (AEDT) [thread overview]
Message-ID: <47d1cl32N3z9sSF@ozlabs.org> (raw)
In-Reply-To: <20191216103058.4958-1-david@redhat.com>
On Mon, 2019-12-16 at 10:30:58 UTC, David Hildenbrand wrote:
> Commit 63341ab03706 (virtio-balloon: fix managed page counts when migrati=
> ng
> pages between zones) fixed a long existing BUG in the virtio-balloon
> driver when pages would get migrated between zones. I did not try to
> reproduce on powerpc, but looking at the code, the same should apply to
> powerpc/cmm ever since it started using the balloon compaction
> infrastructure (luckily just recently).
>
> In case we have to migrate a ballon page to a newpage of another zone, th=
> e
> managed page count of both zones is wrong. Paired with memory offlining
> (which will adjust the managed page count), we can trigger kernel crashes
> and all kinds of different symptoms.
>
> Fix it by properly adjusting the managed page count when migrating if
> the zone changed.
>
> We'll temporarily modify the totalram page count. If this ever becomes a
> problem, we can fine tune by providing helpers that don't touch
> the totalram pages (e.g., adjust_zone_managed_page_count()).
>
> Fixes: fe030c9b85e6 ("powerpc/pseries/cmm: Implement balloon compaction")
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Richard Fontana <rfontana@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Arun KS <arunks@codeaurora.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: David Hildenbrand <david@redhat.com>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/e352f576d345e5bf1fb62c8559851448a6c1d9cd
cheers
WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: David Hildenbrand <david@redhat.com>, linux-kernel@vger.kernel.org
Cc: Richard Fontana <rfontana@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
David Hildenbrand <david@redhat.com>,
linux-mm@kvack.org, Arun KS <arunks@codeaurora.org>,
Paul Mackerras <paulus@samba.org>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2] powerpc/pseries/cmm: fix managed page counts when migrating pages between zones
Date: Wed, 18 Dec 2019 15:05:11 +1100 (AEDT) [thread overview]
Message-ID: <47d1cl32N3z9sSF@ozlabs.org> (raw)
In-Reply-To: <20191216103058.4958-1-david@redhat.com>
On Mon, 2019-12-16 at 10:30:58 UTC, David Hildenbrand wrote:
> Commit 63341ab03706 (virtio-balloon: fix managed page counts when migrati=
> ng
> pages between zones) fixed a long existing BUG in the virtio-balloon
> driver when pages would get migrated between zones. I did not try to
> reproduce on powerpc, but looking at the code, the same should apply to
> powerpc/cmm ever since it started using the balloon compaction
> infrastructure (luckily just recently).
>
> In case we have to migrate a ballon page to a newpage of another zone, th=
> e
> managed page count of both zones is wrong. Paired with memory offlining
> (which will adjust the managed page count), we can trigger kernel crashes
> and all kinds of different symptoms.
>
> Fix it by properly adjusting the managed page count when migrating if
> the zone changed.
>
> We'll temporarily modify the totalram page count. If this ever becomes a
> problem, we can fine tune by providing helpers that don't touch
> the totalram pages (e.g., adjust_zone_managed_page_count()).
>
> Fixes: fe030c9b85e6 ("powerpc/pseries/cmm: Implement balloon compaction")
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Richard Fontana <rfontana@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Arun KS <arunks@codeaurora.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: David Hildenbrand <david@redhat.com>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/e352f576d345e5bf1fb62c8559851448a6c1d9cd
cheers
next prev parent reply other threads:[~2019-12-18 4:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 10:30 [PATCH v2] powerpc/pseries/cmm: fix managed page counts when migrating pages between zones David Hildenbrand
2019-12-16 10:30 ` David Hildenbrand
2019-12-18 4:05 ` Michael Ellerman [this message]
2019-12-18 4:05 ` Michael Ellerman
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