From: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
Nathan Fontenot <nfont@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: Possible LMB hot unplug bug in 4.13+ kernels
Date: Fri, 6 Oct 2017 08:04:52 -0300 [thread overview]
Message-ID: <3bdf3e9d-a2f4-4820-6ecd-a9b14b3c45c4@linux.vnet.ibm.com> (raw)
In-Reply-To: <8760bszxww.fsf@concordia.ellerman.id.au>
> Unless you (Daniel) think there's some reason lmb_is_removable() is
> incorrectly returning false. But most likely it's correct and there's
> just an unmovable allocation in that range.
I am not educated enough to say that the current behavior is wrong. What I
can say is that in 4.11 and older kernels that supports LMB hot
plug/unplug I
didn't see this kernel "refusal" to remove a LMB that was just hotplugged.
Assuming that the kernel is behaving as intended, a QEMU guest started with
4Gb of RAM that receives an extra 1Gb of RAM will not unplug this same 1Gb.
It seems off from the user perspective that a recently added memory is being
considered not removable, thus QEMU will need to keep this limitation in
mind when
dealing with future LMB bugs in 4.13+ kernels.
Thanks,
Daniel
prev parent reply other threads:[~2017-10-06 11:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-04 20:21 Possible LMB hot unplug bug in 4.13+ kernels Daniel Henrique Barboza
2017-10-05 15:43 ` Nathan Fontenot
2017-10-06 4:46 ` Michael Ellerman
2017-10-06 11:04 ` Daniel Henrique Barboza [this message]
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