linux-kernel - Re: [PATCH v2 1/2] mm: reorganize internal_get_user_pages

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Message-ID: <20201030223655.GA6357@xz-x1>
Date:   Fri, 30 Oct 2020 18:36:55 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>,
        Hugh Dickins <hughd@...gle.com>, Jan Kara <jack@...e.cz>,
        Jann Horn <jannh@...gle.com>,
        John Hubbard <jhubbard@...dia.com>,
        Kirill Shutemov <kirill@...temov.name>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Linux-MM <linux-mm@...ck.org>, Michal Hocko <mhocko@...e.com>,
        Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH v2 1/2] mm: reorganize internal_get_user_pages_fast()

On Fri, Oct 30, 2020 at 11:46:20AM -0300, Jason Gunthorpe wrote:
> The next patch in this series makes the lockless flow a little more
> complex, so move the entire block into a new function and remove a level
> of indention. Tidy a bit of cruft:
> 
>  - addr is always the same as start, so use start
> 
>  - Use the modern check_add_overflow() for computing end = start + len
> 
>  - nr_pinned/pages << PAGE_SHIFT needs the LHS to be unsigned long to
>    avoid shift overflow, make the variables unsigned long to avoid coding
>    casts in both places. nr_pinned was missing its cast
> 
>  - The handling of ret and nr_pinned can be streamlined a bit
> 
> No functional change.
> 
> Signed-off-by: Jason Gunthorpe <jgg@...dia.com>

Sorry for a very late reply (due to other distractions):

Reviewed-by: Peter Xu <peterx@...hat.com>

Thanks,

-- 
Peter Xu