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From: Stefano Stabellini <sstabellini@kernel.org>
To: "Jürgen Groß" <jgross@suse.com>
Cc: Julien Grall <julien@xen.org>, Simon Leiner <simon@leiner.me>,
	 xen-devel@lists.xenproject.org, sstabellini@kernel.org
Subject: Re: [PATCH 2/2] arm/xen: Add misuse warning to virt_to_gfn
Date: Thu, 27 Aug 2020 09:04:36 -0700 (PDT)
Message-ID: <alpine.DEB.2.21.2008270903430.4412@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <18229211-c7b5-21bc-f3a9-4a9a1974094e@suse.com>


[-- Attachment #1: Type: text/plain, Size: 1484 bytes --]

On Thu, 27 Aug 2020, Jürgen Groß wrote:
> On 27.08.20 10:24, Julien Grall wrote:
> > 
> > 
> > On 27/08/2020 06:21, Jürgen Groß wrote:
> > > On 26.08.20 20:37, Julien Grall wrote:
> > > "Usually" is a bit gross here. The only generic call site I could find
> > > is xenbus_grant_ring(). All other instances (I counted 22) are not
> > > generic at all.
> > > 
> > > > will only catch one instance and it means we would have to fix the first
> > > > instance and then re-run to catch the others.
> > > > 
> > > > So I think we want to switch to WARN_ON() here.
> > > 
> > > No, please don't. In case there would be a frequent path the result
> > > would be a basically unusable system due to massive console clobbering.
> > 
> > Right, but if that's really happenning then you have a much bigger problem
> > on your platform because the address returned will be invalid.
> > 
> > So I still don't see the advantage of WARN_ON_ONCE() here.
> 
> Depends of the (potential) source of the warnings. I think we can agree
> that e.g. a problem in the pv network stack is rather improbable, as it
> would have been detected long ago.
> 
> If, however, the problem is being introduced by one of the rather new
> pv-drivers (like sound, pvcalls, 9pfs) it is perfectly fine to assume
> the overall system is still functional even without those drivers
> working correctly. Having a message storm from those sources is still
> quite undesirable IMO and doesn't really help.

I agree with this.

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Aw: [Linux] [ARM] Granting memory obtained from the DMA API>
2020-08-25  9:31 ` [PATCH 1/2] xen/xenbus: Fix granting of vmalloc'd memory Simon Leiner
2020-08-25  9:31   ` [PATCH 2/2] arm/xen: Add misuse warning to virt_to_gfn Simon Leiner
2020-08-25 12:16     ` Jan Beulich
2020-08-25 23:48       ` Stefano Stabellini
2020-08-26  6:20         ` Jan Beulich
2020-08-26  7:50           ` Simon Leiner
2020-08-26  7:59             ` Jürgen Groß
2020-08-26  8:14               ` Simon Leiner
2020-08-26  8:27                 ` Jürgen Groß
2020-08-26  8:30                   ` Simon Leiner
2020-08-25 23:58     ` Stefano Stabellini
2020-08-26 18:37     ` Julien Grall
2020-08-27  5:21       ` Jürgen Groß
2020-08-27  8:24         ` Julien Grall
2020-08-27  8:35           ` Jürgen Groß
2020-08-27 16:04             ` Stefano Stabellini [this message]
2020-08-25 23:55   ` [PATCH 1/2] xen/xenbus: Fix granting of vmalloc'd memory Stefano Stabellini

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