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Groups > linux.kernel > #1287508

Re: m(un)map kmalloc buffers to userspace

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: m(un)map kmalloc buffers to userspace
Date 2015-12-09 15:00 +0100
Message-ID <qDNrI-EN-5@gated-at.bofh.it> (permalink)
References <qDup3-5jp-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Tue 08-12-15 18:25:31, Sebastian Frias wrote:
> Hi,
> 
> We are porting a driver from Linux 3.4.39+ to 4.1.13+, CPU is Cortex-A9.
> 
> The driver maps kmalloc'ed memory to user space.

This sounds like a terrible idea to me. Why don't you simply use the
page allocator directly? Try to imagine what would happen if you mmaped
a kmalloc with a size which is not page aligned? mmaped memory uses
whole page granularity.
-- 
Michal Hocko
SUSE Labs
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Thread

m(un)map kmalloc buffers to userspace Sebastian Frias <sebastian_frias@sigmadesigns.com> - 2015-12-08 18:40 +0100
  Re: m(un)map kmalloc buffers to userspace Michal Hocko <mhocko@kernel.org> - 2015-12-09 15:00 +0100
    Re: m(un)map kmalloc buffers to userspace Marc Gonzalez <marc_gonzalez@sigmadesigns.com> - 2015-12-09 15:10 +0100
      Re: m(un)map kmalloc buffers to userspace Michal Hocko <mhocko@kernel.org> - 2015-12-09 15:40 +0100
        Re: m(un)map kmalloc buffers to userspace Sebastian Frias <sebastian_frias@sigmadesigns.com> - 2015-12-09 16:00 +0100
          Re: m(un)map kmalloc buffers to userspace Michal Hocko <mhocko@kernel.org> - 2015-12-09 16:20 +0100
            Re: m(un)map kmalloc buffers to userspace Sebastian Frias <sebastian_frias@sigmadesigns.com> - 2015-12-09 16:40 +0100
              Re: m(un)map kmalloc buffers to userspace Michal Hocko <mhocko@kernel.org> - 2015-12-10 12:50 +0100
                Re: m(un)map kmalloc buffers to userspace Richard Weinberger <richard.weinberger@gmail.com> - 2015-12-10 13:10 +0100
                Re: m(un)map kmalloc buffers to userspace Sebastian Frias <sebastian_frias@sigmadesigns.com> - 2015-12-10 14:40 +0100
                Re: m(un)map kmalloc buffers to userspace Michal Hocko <mhocko@kernel.org> - 2015-12-10 15:10 +0100
                Re: m(un)map kmalloc buffers to userspace Sebastian Frias <sebastian_frias@sigmadesigns.com> - 2015-12-10 17:50 +0100
                Re: m(un)map kmalloc buffers to userspace Michal Hocko <mhocko@kernel.org> - 2015-12-11 10:50 +0100

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