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From: Oliver Neukum <oneukum@suse.com>
To: Christoph Hellwig <hch@infradead.org>,
	Jaewon Kim <jaewon31.kim@gmail.com>
Cc: 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
Date: Thu, 23 May 2019 14:32:09 +0200	[thread overview]
Message-ID: <1558614729.3994.5.camel@suse.com> (raw)
In-Reply-To: <20190520055657.GA31866@infradead.org>

On So, 2019-05-19 at 22:56 -0700, Christoph Hellwig wrote:
> Folks, you can't just pass arbitary GFP_ flags to dma allocation
> routines, beause very often they are not just wrappers around
> the page allocator.
> 
> So no, you can't just fine grained control the flags, but the
> existing code is just as buggy.
> 
> 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?

	Regards
		Oliver


  parent reply	other threads:[~2019-05-23 12:45 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-17 16:02 [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation Jaewon Kim
2019-05-17 16:34 ` Matthew Wilcox
2019-05-18  1:53   ` Jaewon Kim
2019-05-20  5:56 ` Christoph Hellwig
2019-05-20  9:09   ` Oliver Neukum
2019-05-20 10:12     ` Christoph Hellwig
2019-05-20 14:16       ` Alan Stern
2019-05-20 14:23         ` Christoph Hellwig
2019-05-21  8:54           ` Oliver Neukum
2019-05-21 13:27             ` Christoph Hellwig
2019-05-21 13:11         ` Oliver Neukum
2019-05-21 14:00           ` Alan Stern
2019-05-22  6:31             ` Oliver Neukum
2019-05-22 14:56               ` Alan Stern
2019-05-22 20:47                 ` Oliver Neukum
2019-05-23 14:01                   ` Alan Stern
2019-05-28 12:34                     ` Oliver Neukum
2019-05-28 14:25                       ` Alan Stern
2019-05-23 12:32   ` Oliver Neukum [this message]
2019-05-23 16:35     ` Christoph Hellwig

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