linux-kernel - Re: [PATCH 1/2] x86/pkeys: properly copy pkey state at fork()

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Message-ID: <8f509b82-4b1f-d70c-4f44-48d8194469ee@intel.com>
Date:   Thu, 3 Jan 2019 10:54:16 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Sasha Levin <sashal@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Will Deacon <will.deacon@....com>,
        Andy Lutomirski <luto@...nel.org>,
        Joerg Roedel <jroedel@...e.de>, stable@...r.kernel.org
Subject: Re: [PATCH 1/2] x86/pkeys: properly copy pkey state at fork()

On 1/3/19 5:52 AM, Sasha Levin wrote:
> This commit has been processed because it contains a "Fixes:" tag,
> fixing commit: e8c24d3a23a4 x86/pkeys: Allocation/free syscalls.
> 
> The bot has tested the following trees: v4.20.0, v4.19.13, v4.14.91, v4.9.148, 
> 
> v4.20.0: Build OK!
> v4.19.13: Build OK!
> v4.14.91: Build OK!
> v4.9.148: Failed to apply! Possible dependencies:
>     c10e83f598d0 ("arch, mm: Allow arch_dup_mmap() to fail")
> 
> 
> How should we proceed with this patch?

The 4.9 version of arch_dup_mmap() does not contain the
ldt_dup_context() line.  We just need to add arch_dup_pkeys(), like so:

 void arch_dup_mmap(struct mm_struct *oldmm,
                                 struct mm_struct *mm)
 {
+       arch_dup_pkeys(oldmm, mm);
        paravirt_arch_dup_mmap(oldmm, mm);
 }

Should be a pretty simple merge.  We can basically ignore the
ldt_dup_context() changes.