Re: [patch] mremap.2: Add description of old_size == 0 functionality

On 09/17/2017 06:52 PM, Jann Horn wrote:

On Fri, Sep 15, 2017 at 2:37 PM, Mike Kravetz [off-list ref] wrote:
[...]

quoted

A recent change was made to mremap so that an attempt to create a
duplicate a private mapping will fail.

commit dba58d3b8c5045ad89c1c95d33d01451e3964db7
Author: Mike Kravetz [off-list ref]
Date:   Wed Sep 6 16:20:55 2017 -0700

    mm/mremap: fail map duplication attempts for private mappings

This return code is also documented here.

[...]

quoted

diff --git a/man2/mremap.2 b/man2/mremap.2

[...]

quoted

@@ -174,7 +189,12 @@ and
 or
 .B MREMAP_FIXED
 was specified without also specifying
-.BR MREMAP_MAYMOVE .
+.BR MREMAP_MAYMOVE ;
+or \fIold_size\fP was zero and \fIold_address\fP does not refer to a
+private anonymous mapping;

Shouldn't this be the other way around? "or old_size was zero and
old_address refers to a private anonymous mapping"?

Thanks Jann,

Yes that is wrong.  In addition, the description of this functionality
in the section before this is also incorrect.

I will fix both in a new version of the patch.

-- 
Mike Kravetz

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