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Re: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not freeing pud v3

From Jerome Glisse <jglisse@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not freeing pud v3
Date 2017-06-26 16:50 +0200
Message-ID <tWDuX-3Bo-39@gated-at.bofh.it> (permalink)
References <tVXFo-2HS-15@gated-at.bofh.it> <tWyOC-EC-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Jun 26, 2017 at 11:43:04AM +0200, Ingo Molnar wrote:
> 
> * jglisse@redhat.com <jglisse@redhat.com> wrote:
> 
> > From: Jérôme Glisse <jglisse@redhat.com>
> > 
> > With commit af2cf278ef4f we no longer free pud so that we do not
> > have synchronize all pgd on hotremove/vfree. But the new 5 level
> > page table patchset reverted that for 4 level page table.
> > 
> > This patch restore af2cf278ef4f and disable free_pud() if we are
> > in the 4 level page table case thus avoiding BUG_ON() after hot-
> > remove.
> > 
> > af2cf278ef4f x86/mm/hotplug: Don't remove PGD entries in remove_pagetable()
> 
> Am I correct that the _real_ buggy commit that introduced the breakage in v4.12 
> is:
> 
>   f2a6a7050109: ("x86: Convert the rest of the code to support p4d_t")
> 
> ... right?

Correct.

Jérôme

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Thread

[PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not freeing pud v3 jglisse@redhat.com - 2017-06-24 20:10 +0200
  Re: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not  freeing pud v3 Ingo Molnar <mingo@kernel.org> - 2017-06-26 11:50 +0200
    Re: [PATCH] x86/mm/hotplug: fix BUG_ON() after hotremove by not  freeing pud v3 Jerome Glisse <jglisse@redhat.com> - 2017-06-26 16:50 +0200
  [tip:x86/urgent] x86/mm/hotplug: Fix BUG_ON() after hot-remove by  not freeing PUD "tip-bot for Jérôme Glisse" <tipbot@zytor.com> - 2017-06-27 09:30 +0200

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