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From: Matthew Wilcox <willy@infradead.org>
To: Po-Hao Su <supohaosu@gmail.com>
Cc: linux-mm@kvack.org
Subject: Re: do_mmap Function Issue Report
Date: Wed, 28 Mar 2018 10:04:07 -0700	[thread overview]
Message-ID: <20180328170407.GB639@bombadil.infradead.org> (raw)
In-Reply-To: <CAD5U=y8Q-9G+6n9bRs1BbirwhAJ5z0-CS7sG1q8ypqLaDyyHgQ@mail.gmail.com>

On Wed, Mar 28, 2018 at 11:19:30PM +0800, Po-Hao Su wrote:
> I am writing in reference to report a bug in *do_mmap(...)* function.
> Recently, I found that there seems a bug after *get_unmapped_area(...)
> *function
> is return.
> *do_mmap(...) *function will check the *addr *parameter is aligned on a
> page boundary or not after *get_unmapped_area(...)* function is return.
> But it will return *addr *parameter, not an error(probably to *-EINVAL*)
> while address not aligned on a page boundary.
> Therefore, I think address not aligned on a page boundary should be an
> error(*-EINVAL*).

Hi Po-Hao,

I'm afraid you've misunderstood the intent of this code.  The 'addr'
returned from get_unmapped_area() may be an errno, in which case we
want to return it.  Successful invocations of get_unmapped_area do,
of course, return an aligned address.  Your patch would make us return
-EINVAL for all errors, covering up the actual cause of the error (eg
-ENOMEM or -ENODEV)

      reply	other threads:[~2018-03-28 17:04 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-28 15:19 do_mmap Function Issue Report Po-Hao Su
2018-03-28 17:04 ` Matthew Wilcox [this message]

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