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Date:   Sat, 15 Feb 2020 17:29:06 -0800 (PST)
From:   David Rientjes <rientjes@google.com>
To:     Mina Almasry <almasrymina@google.com>
cc:     mike.kravetz@oracle.com, shuah@kernel.org, shakeelb@google.com,
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Subject: Re: [PATCH v12 5/9] hugetlb_cgroup: add accounting for shared
 mappings
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On Tue, 11 Feb 2020, Mina Almasry wrote:

> For shared mappings, the pointer to the hugetlb_cgroup to uncharge lives
> in the resv_map entries, in file_region->reservation_counter.
> 
> After a call to region_chg, we charge the approprate hugetlb_cgroup, and if
> successful, we pass on the hugetlb_cgroup info to a follow up region_add call.
> When a file_region entry is added to the resv_map via region_add, we put the
> pointer to that cgroup in file_region->reservation_counter. If charging doesn't
> succeed, we report the error to the caller, so that the kernel fails the
> reservation.
> 
> On region_del, which is when the hugetlb memory is unreserved, we also uncharge
> the file_region->reservation_counter.
> 
> Signed-off-by: Mina Almasry <almasrymina@google.com>
> 

Does this develop a dependency on hugetlb_cgroup.h in hugetlb.h?  Or maybe 
we only need a forward declaration of struct file_region there?