linux-kernel - Re: [PATCH 1/3] powerpc/mm: move mmap_sem unlock up from do

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Message-Id: <87a88fowgl.fsf@skywalker.in.ibm.com>
Date:   Tue, 21 Mar 2017 14:09:06 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:     Laurent Dufour <ldufour@...ux.vnet.ibm.com>, mpe@...erman.id.au,
        benh@...nel.crashing.org, paulus@...ba.org, bsingharora@...il.com,
        npiggin@...il.com
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] powerpc/mm: move mmap_sem unlock up from do_sigbus

Laurent Dufour <ldufour@...ux.vnet.ibm.com> writes:

> Move mmap_sem releasing in the do_sigbus()'s unique caller : mm_fault_error()
>
> No functional changes.
>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>

> Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/mm/fault.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index 62a50d6d1053..ee09604bbe12 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -119,8 +119,6 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address,
>  	siginfo_t info;
>  	unsigned int lsb = 0;
>
> -	up_read(&current->mm->mmap_sem);
> -
>  	if (!user_mode(regs))
>  		return MM_FAULT_ERR(SIGBUS);
>
> @@ -184,8 +182,10 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault)
>  		return MM_FAULT_RETURN;
>  	}
>
> -	if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE))
> +	if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
> +		up_read(&current->mm->mmap_sem);
>  		return do_sigbus(regs, addr, fault);
> +	}
>
>  	/* We don't understand the fault code, this is fatal */
>  	BUG();
> -- 
> 2.7.4