RE: [PATCH v2 4/5] cramfs: add mmap support

From	Chris Brandt <Chris.Brandt@renesas.com>
Newsgroups	linux.kernel
Subject	RE: [PATCH v2 4/5] cramfs: add mmap support
Date	2017-08-29 21:40 +0200
Message-ID	<ujUwG-6Me-27@gated-at.bofh.it> (permalink)
References	(1 earlier) <ufasq-1zg-9@gated-at.bofh.it> <ujm1Y-2ab-15@gated-at.bofh.it> <ujsqL-6aY-33@gated-at.bofh.it> <ujtd9-6G2-43@gated-at.bofh.it> <ujxJM-13g-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Monday, August 28, 2017, Nicolas Pitre wrote:
> OK I moved the lock promotion right at the beginning _before_ validating
> the split point. Also got a reference on the file to make sure that
> hasn't changed too.
> 
> > While we are at it, what happens if you mmap 120Kb, then munmap() the
> middle
> > 40Kb.  Leaving two 40Kb VMAs with 40Kb gap between them, that is.  Will
> your
> > ->vm_private_data be correct for both?
> 
> It wouldn't, but I now changed it to contain absolute values so now it
> will. And if the split point lands in the hole then the code just
> readjusts the pgoff at the beginning of the remaining part.
> 
> Here's the revised patch:

For whatever it's worth, as soon as I moved to 4.13-rc7,
CONFIG_CRAMFS_PHYSMEM=y crashes my XIP_KERNEL system before it can even 
get to any console output.

(both the old patch and the new patch)

If CONFIG_CRAMFS_PHYSMEM is not set, my XIP system boots fine.

However, if I boot -rc7 as a uImage, the new patch works just as good as
the old patch.

(mounting after boot, or booting with rootfstype=cramfs_physmem)

I guess I'll have to figure out what happened between -rc4 and -rc7.
Damn!

Chris

Thread

Re: [PATCH v2 4/5] cramfs: add mmap support Al Viro <viro@ZenIV.linux.org.uk> - 2017-08-28 08:50 +0200
  Re: [PATCH v2 4/5] cramfs: add mmap support Nicolas Pitre <nicolas.pitre@linaro.org> - 2017-08-28 15:40 +0200
    Re: [PATCH v2 4/5] cramfs: add mmap support Al Viro <viro@ZenIV.linux.org.uk> - 2017-08-28 16:30 +0200
      Re: [PATCH v2 4/5] cramfs: add mmap support Nicolas Pitre <nicolas.pitre@linaro.org> - 2017-08-28 21:20 +0200
        RE: [PATCH v2 4/5] cramfs: add mmap support Chris Brandt <Chris.Brandt@renesas.com> - 2017-08-29 21:40 +0200
          RE: [PATCH v2 4/5] cramfs: add mmap support Nicolas Pitre <nicolas.pitre@linaro.org> - 2017-08-29 22:10 +0200
            RE: [PATCH v2 4/5] cramfs: add mmap support Chris Brandt <Chris.Brandt@renesas.com> - 2017-08-29 22:20 +0200
            RE: [PATCH v2 4/5] cramfs: add mmap support Chris Brandt <Chris.Brandt@renesas.com> - 2017-08-31 04:40 +0200

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