man page mlock/munlock

man page mlock/munlock

[Mehdi Aqadjani Memar]

Dear Michael Kerrisk,
in my application I am using munlock() as described in the man page. munlock()
fails and returns ENOMEM. The man page for this error has not helped me to find
out what the problem was. I traced my code and discovered that this error
appears when "the process's maximum number of mappings would have been
exceeded", as it is mentioned at the man page of mmap(). This happens because
munlock() splits the vma's.
I believe that this information should be a part of the man page of munlock().
-- 
Met vriendelijke groet/Kind regards
Mehdi Aqadjani Memar
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Re: man page mlock/munlock

[Michael Kerrisk (man-pages)]

Hello Mehdi

On 6 May 2015 at 10:49, Mehdi Aqadjani Memar
<m.aqadjanimemar-oe7qfRrRQfcprfpi5Sxi9A@public.gmane.org> wrote:
> Dear Michael Kerrisk,
> in my application I am using munlock() as described in the man page. munlock()
> fails and returns ENOMEM. The man page for this error has not helped me to find
> out what the problem was. I traced my code and discovered that this error
> appears when "the process's maximum number of mappings would have been
> exceeded", as it is mentioned at the man page of mmap(). This happens because
> munlock() splits the vma's.
> I believe that this information should be a part of the man page of munlock().
> --
> Met vriendelijke groet/Kind regards
> Mehdi Aqadjani Memar

Thanks for the report, and sorry for the delayed response. I've
confirmed your point. How would the following text be:

       ENOMEM Locking  or  unlocking  a region would result in the total
              number of mappings with distinct attributes (e.g.,  locked
              versus  unlocked)  exceeding  the  allowed  maximum.  (For
              example, unlocking a range in the middle  of  a  currently
              locked  mapping would result in three mappings: two locked
              mappings at each end and an unlocked mapping in  the  mid‐
              dle.)
?

Thanks,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: man page mlock/munlock

[Mehdi Aqadjani Memar]

Hello Michael,
thank you for your reply!
Your text has explained the effect of locking and unlocking very well.
Regards,
Mehdi

Michael Kerrisk (man-pages) writes:

> Hello Mehdi
>
> On 6 May 2015 at 10:49, Mehdi Aqadjani Memar
> <m.aqadjanimemar-oe7qfRrRQfcprfpi5Sxi9A@public.gmane.org> wrote:
>> Dear Michael Kerrisk,
>> in my application I am using munlock() as described in the man page. munlock()
>> fails and returns ENOMEM. The man page for this error has not helped me to find
>> out what the problem was. I traced my code and discovered that this error
>> appears when "the process's maximum number of mappings would have been
>> exceeded", as it is mentioned at the man page of mmap(). This happens because
>> munlock() splits the vma's.
>> I believe that this information should be a part of the man page of munlock().
>> --
>> Met vriendelijke groet/Kind regards
>> Mehdi Aqadjani Memar
>
> Thanks for the report, and sorry for the delayed response. I've
> confirmed your point. How would the following text be:
>
>        ENOMEM Locking  or  unlocking  a region would result in the total
>               number of mappings with distinct attributes (e.g.,  locked
>               versus  unlocked)  exceeding  the  allowed  maximum.  (For
>               example, unlocking a range in the middle  of  a  currently
>               locked  mapping would result in three mappings: two locked
>               mappings at each end and an unlocked mapping in  the  mid‐
>               dle.)
> ?
>
> Thanks,
>
> Michael

-- 
Met vriendelijke groet/Kind regards
Mehdi Aqadjani Memar
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