linux-kernel - Re: [PATCH v3 04/28] mm: allow VM_FAULT

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Message-ID: <20190419060057.GE13323@xz-x1>
Date:   Fri, 19 Apr 2019 14:00:57 +0800
From:   Peter Xu <peterx@...hat.com>
To:     Jerome Glisse <jglisse@...hat.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        David Hildenbrand <david@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Maya Gokhale <gokhale2@...l.gov>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Martin Cracauer <cracauer@...s.org>, Shaohua Li <shli@...com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Denis Plotnikov <dplotnikov@...tuozzo.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        Marty McFadden <mcfadden8@...l.gov>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: Re: [PATCH v3 04/28] mm: allow VM_FAULT_RETRY for multiple times

On Thu, Apr 18, 2019 at 04:11:08PM -0400, Jerome Glisse wrote:

[...]

> Reviewed-by: Jérôme Glisse <jglisse@...hat.com>
> 
> A minor comment suggestion below but it can be fix in a followup patch.

[...]

> > +/*
> > + * Returns true if the page fault allows retry and this is the first
> > + * attempt of the fault handling; false otherwise.  This is mostly
> > + * used for places where we want to try to avoid taking the mmap_sem
> > + * for too long a time when waiting for another condition to change,
> > + * in which case we can try to be polite to release the mmap_sem in
> > + * the first round to avoid potential starvation of other processes
> > + * that would also want the mmap_sem.
> > + */
> 
> You should be using kernel function documentation style above.

I'm switching to this:

/**
 * fault_flag_allow_retry_first - check ALLOW_RETRY the first time
 *
 * This is mostly used for places where we want to try to avoid taking
 * the mmap_sem for too long a time when waiting for another condition
 * to change, in which case we can try to be polite to release the
 * mmap_sem in the first round to avoid potential starvation of other
 * processes that would also want the mmap_sem.
 *
 * Return: true if the page fault allows retry and this is the first
 * attempt of the fault handling; false otherwise.
 */

I'm still keeping the r-b, assuming that's ok.

Thanks!

-- 
Peter Xu