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From:   David Howells <dhowells@redhat.com>
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Subject: Re: [PATCH] mm: Move check for SHRINKER_NUMA_AWARE to do_shrink_slab()
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Date:   Fri, 03 Aug 2018 12:18:45 +0100
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David Howells <dhowells@redhat.com> wrote:

> But!  I'm not sure why the reproducer works at all because the umount2() call
> is *after* the chroot, so should fail on ENOENT before it even gets that
> far.

No, it shouldn't.  It did chroot() not chdir().

> In fact, umount2() can be called multiple times, apparently successfully, and
> doesn't actually unmount anything.

Okay, because it chroot'd into the directory.  Should it return EBUSY though?

David