linux-kernel - Re: [PATCH] Revert "x86/mm: implement free pmd/pte page interfaces"

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Date:   Thu, 26 Apr 2018 17:27:12 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
        Michal Hocko <mhocko@...e.com>, Borislav Petkov <bp@...e.de>,
        Matthew Wilcox <willy@...radead.org>, stable@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, x86@...nel.org,
        Toshi Kani <toshi.kani@....com>, Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH] Revert "x86/mm: implement free pmd/pte page interfaces"

On Thu, Apr 26, 2018 at 05:14:07PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> This reverts commit 28ee90fe6048fa7b7ceaeb8831c0e4e454a4cf89.
> 
> This commit is broken for x86, as it unmaps the PTE and PMD
> pages and immediatly frees them without doing a TLB flush.
> 
> Further this lacks synchronization with other page-tables in
> the system when the PMD pages are not shared between
> mm_structs.
> 
> On x86-32 with PAE and PTI patches on-top this patch
> triggers the BUG_ON in vmalloc_sync_one() because the kernel
> and the process page-table were not synchronized.
> 
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>  arch/x86/mm/pgtable.c | 28 ++--------------------------
>  1 file changed, 2 insertions(+), 26 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>