Messages in this thread | | | Date | Mon, 17 Sep 2018 17:24:24 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v3 1/3] exec: separate thread_count for files_struct |
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On 09/16, Eric W. Biederman wrote: > > Oleg Nesterov <oleg@redhat.com> writes: > > > As for binder.c, in this case we probably actually want to unshare ->files > > on exec so we can ignore it? > > Looking at the binder case it only captures ->files on mmap. Exec > ditches the mmap. So if the order of operations are correct than > the dropping of the old mm will also drop the count on files_struct > held by binder. > > So semantically binder should not effect locks on exec,
Agreed, but it does.
Before your "[PATCH 0/3] exec: Moving unshare_files_struct" unshare_files() is called before exec_mmap().
And even with this series we can have another CLONE_VM process.
Howver, I think this doesn't really matter. binder does __fd_install(files), so if it actually has a reference to execing_task->files, I think it should be unshared anyway.
> In short as long as we get the oder of operations correct we should be > able to safely ignore binder, and not have binder affect the results of > this code.
Agreed.
Oleg.
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