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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 21 Jun 2018 05:13:39 +0300
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Subject: Re: [PATCH v3 3/5] bitmap: Add bitmap_alloc(), bitmap_zalloc() and bitmap_free()
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        agk@redhat.com, Mike Snitzer <snitzer@redhat.com>,
        device-mapper development <dm-devel@redhat.com>,
        shli@kernel.org, linux-raid@vger.kernel.org,
        "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        Yury Norov <ynorov@caviumnetworks.com>,
        lkml <linux-kernel@vger.kernel.org>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Joe Perches <joe@perches.com>
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On Tue, Jun 19, 2018 at 2:10 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Mon, 18 Jun 2018 15:01:43 -0700 Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:

>> We can't as we end up including bitmap.h (by the way of cpumask.h)
>> form slab.h, so we gen circular dependency.
>

It's not just so easy. See below.

> That info should have been in the changelog, and probably a code
> comment.
>
>> Maybe if we removed memcg
>> stuff from slab.h so we do not need to include workqueue.h...
>
> Or move the basic slab API stuff out of slab.h into a new header.  Or
> create a new, standalone work_struct.h - that looks pretty simple.

I tried to move out work_struct, it didn't help. There are actually
several circular dependencies that ends in bitmap.h either way or
another.

First one is

slab.h -> gfp.h -> mmzone.h -> nodemask.h -> bitmap.h

And so on...

Splitting out kXalloc stuff to a separate header won't help, I think,
because of the above.
Splitting out struct work_struct is just a tip of an iceberg.
Splitting out memcg stuff won't help in the similar way.

I'm all ears for (a better) solution.

-- 
With Best Regards,
Andy Shevchenko