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Subject: Re: [PATCH v7] mremap.2: Add information for MREMAP_DONTUNMAP.
To:     Brian Geffon <bgeffon@google.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     "Michael S . Tsirkin" <mst@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-api@vger.kernel.org,
        Andy Lutomirski <luto@amacapital.net>,
        Will Deacon <will@kernel.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Sonny Rao <sonnyrao@google.com>,
        Minchan Kim <minchan@kernel.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Yu Zhao <yuzhao@google.com>,
        Jesse Barnes <jsbarnes@google.com>,
        Florian Weimer <fweimer@redhat.com>,
        "Kirill A . Shutemov" <kirill@shutemov.name>,
        mtk.manpages@gmail.com, linux-man@vger.kernel.org
References: <20200221174248.244748-1-bgeffon@google.com>
 <20200221174248.244748-3-bgeffon@google.com>
From:   Vlastimil Babka <vbabka@suse.cz>
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Date:   Tue, 25 Feb 2020 14:51:34 +0100
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On 2/21/20 6:42 PM, Brian Geffon wrote:
> @@ -209,10 +227,20 @@ flag was not specified.
>  .RE
>  .TP
>  .B ENOMEM
> +Not enough memory was available to complete the operation.
> +Possible causes are:
> +.RS
> +.IP * 3
>  The memory area cannot be expanded at the current virtual address, and the
>  .B MREMAP_MAYMOVE
>  flag is not set in \fIflags\fP.
>  Or, there is not enough (virtual) memory available.
> +.IP *
> +.B MREMAP_DONTUNMAP
> +was used without
> +.B MREMAP_FIXED
> +causing a new mapping to be created that would exceed the virtual memory available or it would exceed the maximum number of allowed mappings.

So this can also result with MREMAP_FIXED, no?

> +.RE
>  .SH CONFORMING TO
>  This call is Linux-specific, and should not be used in programs
>  intended to be portable.
>