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Date:   Tue, 6 Nov 2018 14:11:31 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Alexey Skidanov <alexey.skidanov@intel.com>
Cc:     sbates@raithlin.com, logang@deltatee.com, danielmentz@google.com,
        mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org,
        labbott@redhat.com
Subject: Re: [PATCH] lib/genaloc: Fix allocation of aligned buffer from
 non-aligned chunk
Message-Id: <20181106141131.76e94f6b1ff2859d96792aca@linux-foundation.org>
In-Reply-To: <1541506853-10685-1-git-send-email-alexey.skidanov@intel.com>
References: <1541506853-10685-1-git-send-email-alexey.skidanov@intel.com>
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On Tue,  6 Nov 2018 14:20:53 +0200 Alexey Skidanov <alexey.skidanov@intel.com> wrote:

> On success, gen_pool_first_fit_align() returns the bit number such that
> chunk_start_addr + (bit << order) is properly aligned. On failure,
> the bitmap size parameter is returned.
> 
> When the chunk_start_addr isn't aligned properly, the
> chunk_start_addr + (bit << order) isn't aligned too.
> 
> To fix this, gen_pool_first_fit_align() takes into account
> the chunk_start_addr alignment and returns the bit value such that
> chunk_start_addr + (bit << order) is properly aligned
> (exactly as it done in CMA).

Why does this need "fixing"?  Are there current callers which can
misalign chunk_start_addr?  Or is there a requirement that future
callers can misalign chunk_start_addr?