linux-kernel - Re: [PATCH] drivers/dax: Avoiding potential deadlock

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Message-ID: <CAMvNc9A3E7QxpzLrzU8wM7U5k_Kt_=5JjWp6MyY99sRPtKHbZg@mail.gmail.com>
Date:   Tue, 11 Apr 2017 10:57:31 +0530
From:   Pushkar Jambhlekar <pushkar.iit@...il.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Dave Jiang <dave.jiang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drivers/dax: Avoiding potential deadlock

Sent out another patch to correct return value.

On Tue, Apr 11, 2017 at 10:25 AM, Dan Williams <dan.j.williams@...el.com> wrote:
> On Mon, Apr 10, 2017 at 9:45 PM, Pushkar Jambhlekar
> <pushkar.iit@...il.com> wrote:
>> dax_dev_huge_fault returning without releasing lock. Making code change to avoid this situation
>>
>> Signed-off-by: Pushkar Jambhlekar <pushkar.iit@...il.com>
>> ---
>>  drivers/dax/dax.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
>> index 0d1ca24..fd9c4db 100644
>> --- a/drivers/dax/dax.c
>> +++ b/drivers/dax/dax.c
>> @@ -590,7 +590,7 @@ static int dax_dev_huge_fault(struct vm_fault *vmf,
>>                 rc = __dax_dev_pud_fault(dax_dev, vmf);
>>                 break;
>>         default:
>> -               return VM_FAULT_FALLBACK;
>> +               rc = VM_FAULT_FALLBACK;
>
> Thanks for the fix! Luckily we never take that branch, but we should
> fix it so we don't trip over it in some future where there are more
> fault sizes than pte, pmd, and pud. However, it should be setting rc
> to VM_FAULT_SIGBUS on an unknown / unsupported fault size.



-- 
Jambhlekar Pushkar Arun