linux-kernel - Re: [PATCH v1] ALSA: memalloc: Fix indefinite hang in non-iommu case

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Fri, 16 Feb 2024 09:35:32 +0100
From: Takashi Iwai <tiwai@...e.de>
To: Hillf Danton <hdanton@...a.com>
Cc: Takashi Iwai <tiwai@...e.de>,
	Sven van Ashbrook <svenva@...omium.org>,
	Karthikeyan Ramasubramanian <kramasub@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Brian Geffon <bgeffon@...gle.com>,
	linux-sound@...r.kernel.org,
	Kai Vehmanen <kai.vehmanen@...ux.intel.com>
Subject: Re: [PATCH v1] ALSA: memalloc: Fix indefinite hang in non-iommu case

On Fri, 16 Feb 2024 05:34:24 +0100,
Hillf Danton wrote:
> 
> On Thu, 15 Feb 2024 18:03:01 +0100 Takashi Iwai <tiwai@...e.de> wrote:
> > 
> > So it sounds like that we should go back for __GFP_NORETRY in general
> > for non-zero order allocations, not only the call you changed, as
> > __GFP_RETRY_MAYFAIL doesn't guarantee the stuck.
> > 
> > How about the changes like below?
> > 
> > +/* default GFP bits for our allocations */
> > +static gfp_t default_gfp(size_t size)
> > +{
> > +	/* don't allocate intensively for high-order pages */
> > +	if (size > PAGE_SIZE)
> > +		return GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY;
> > +	else
> > +		return GFP_KERNEL | __GFP_NOWARN | __GFP_RETRY_MAYFAIL;
> > +}
> 
> Looks like an overdose because both __GFP_NORETRY and __GFP_RETRY_MAYFAIL
> are checked in __alloc_pages_slowpath().

If the check there worked as expected, this shouldn't have been a
problem, no?

The fact that we have to drop __GFP_RETRY_MAYFAIL indicates that the
handling there doesn't suffice -- at least for the audio operation.


thanks,

Takashi