linux-kernel - Re: [PATCH] x86/vdso: Change return type to vm_fault

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Message-ID: <CAFqt6zZHo3frivz0Qjj7v2ifF-p+6530Bb8HZqO3iPrL9kemuA@mail.gmail.com>
Date:   Mon, 25 Jun 2018 21:45:50 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, brajeswar.linux@...il.com,
        Sabyasachi Gupta <sabyasachi.linux@...il.com>
Subject: Re: [PATCH] x86/vdso: Change return type to vm_fault_t for fault handlers

On Mon, Jun 25, 2018 at 9:41 PM, Andy Lutomirski <luto@...capital.net> wrote:
> On Mon, Jun 25, 2018 at 8:55 AM Souptick Joarder <jrdr.linux@...il.com> wrote:
>>
>> Use new return type vm_fault_t for fault handler. For
>> now, this is just documenting that the function returns
>> a VM_FAULT value rather than an errno. Once all instances
>> are converted, vm_fault_t will become a distinct type.
>
> Whoa there..  Your commit message makes it sound like you're just
> changing the return type, but:
>
>>                 if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
>> -                       ret = vm_insert_pfn(vma, vmf->address,
>> +                       ret = vmf_insert_pfn(vma, vmf->address,
>>                                             vmalloc_to_pfn(tsc_pg));
>>         }
>>
>> -       if (ret == 0 || ret == -EBUSY)
>> -               return VM_FAULT_NOPAGE;
>> -
>> -       return VM_FAULT_SIGBUS;
>> +       return ret;
>
> You're refactoring the code, too.
>
> Please fix your changelog.


I have mentioned it.

********************
Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t")

Previously vm_insert_pfn() returns err which has to
mapped into VM_FAULT_* type. The new function
vmf_insert_pfn() will replace this inefficiency by
returning VM_FAULT_* type.
*********************