Re: msync() needed before munmap() when writing to shared mapping?

[Andrew Morton]

Jamie Lokier <jamie@xxxxxxxxxxxxx> wrote:
>
> I've followed the logic from do_munmap() and it looks good:
> unmap_vmas->zap_pte_range->page_remove_rmap->set_page_dirty.
> 
> Can someone confirm this is correct, please?

yup, zap_pte_range() transfers pte dirtiness into pagecache dirtiness when
tearing down the mapping, leaving the dirty page floating about in
pagecache for kupdate/kswapd/fsync to catch.  Longstanding behaviour.

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