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Date:   Thu, 23 May 2019 09:35:49 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Oliver Neukum <oneukum@suse.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Jaewon Kim <jaewon31.kim@gmail.com>, linux-mm@kvack.org,
        gregkh@linuxfoundation.org, Jaewon Kim <jaewon31.kim@samsung.com>,
        m.szyprowski@samsung.com, ytk.lee@samsung.com,
        linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation
Message-ID: <20190523163549.GA8692@infradead.org>
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 <20190520055657.GA31866@infradead.org>
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On Thu, May 23, 2019 at 02:32:09PM +0200, Oliver Neukum wrote:
> > Please switch to use memalloc_noio_save() instead.
> 
> Thinking about this again, we have a problem. We introduced
> memalloc_noio_save() in 3.10 . Hence the code should have been
> correct in v4.14. Which means that either
> 6518202970c1 "(mm/cma: remove unsupported gfp_mask
> parameter from cma_alloc()"
> is buggy, or the original issue with a delay of 2 seconds
> still exist.
> 
> Do we need to do something?

cma_alloc calls into alloc_contig_range to do the actual allocation,
which then calls current_gfp_context() to pick up the adjustments
from memalloc_noio_save and friends.  So at least in current mainline
we should be fine.