From: Jason Gunthorpe <jgg@ziepe.ca>
To: David Woodhouse <dwmw2@infradead.org>
Cc: "Michal Hocko" <mhocko@suse.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"David Hildenbrand" <david@kernel.org>,
"Lorenzo Stoakes" <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
"Vlastimil Babka" <vbabka@kernel.org>,
"Mike Rapoport" <rppt@kernel.org>,
"Suren Baghdasaryan" <surenb@google.com>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
"Clark Williams" <clrkwllms@kernel.org>,
"Simona Vetter" <simona.vetter@ffwll.ch>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Christian König" <christian.koenig@amd.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Sean Christopherson" <seanjc@google.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
linux-mm@kvack.org, kvm@vger.kernel.org,
linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/mmu_notifier: Remove non_block_start/end() from notifier invocation
Date: Wed, 12 Aug 2026 09:27:59 -0300 [thread overview]
Message-ID: <20260812122759.GA662699@ziepe.ca> (raw)
In-Reply-To: <44c51ace9b0dc44b795f6f48c91cda440eed910b.camel@infradead.org>
On Wed, Aug 12, 2026 at 09:21:31AM +0100, David Woodhouse wrote:
> On Wed, 2026-08-12 at 10:14 +0200, Michal Hocko wrote:
> > On Tue 11-08-26 16:24:48, David Woodhouse wrote:
> > [...]
> > > I had a second reason for disabling the overzealous check too: to allow
> > > SRCU grace periods within the notifier callbacks.
> >
> > Is there a way that srcu barrier could cause an indirect dependency on
> > memory allocation? In other words what might block the scru to complete?
>
> Not after https://lore.kernel.org/all/6eed3fe3461e9690b486ca98fa7563f60d3940ff.camel@infradead.org/
The user of the SRCU might have a read side that wraps an allocate. In
general it is not safe.
I'm skeptical that without special API and documentation the KVM
special use of SRCU you've outlined will not remain working long term
too..
Jason
next prev parent reply other threads:[~2026-08-12 12:28 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-11 8:58 [PATCH] mm/mmu_notifier: Remove non_block_start/end() from notifier invocation David Woodhouse
2026-08-11 13:55 ` Jason Gunthorpe
2026-08-11 14:21 ` David Woodhouse
2026-08-11 14:27 ` Jason Gunthorpe
2026-08-11 14:33 ` David Woodhouse
2026-08-11 14:42 ` Steven Rostedt
2026-08-11 15:24 ` David Woodhouse
2026-08-11 15:30 ` Jason Gunthorpe
2026-08-12 8:14 ` Michal Hocko
2026-08-12 8:21 ` David Woodhouse
2026-08-12 12:27 ` Jason Gunthorpe [this message]
2026-08-12 8:13 ` Michal Hocko
2026-08-11 15:29 ` Jason Gunthorpe
2026-08-11 15:15 ` David Woodhouse
2026-08-11 15:24 ` Jason Gunthorpe
2026-08-11 15:29 ` David Woodhouse
2026-08-11 16:24 ` Jason Gunthorpe
2026-08-11 17:22 ` David Woodhouse
2026-08-11 17:26 ` Jason Gunthorpe
2026-08-11 17:59 ` David Woodhouse
2026-08-11 18:19 ` Jason Gunthorpe
2026-08-11 20:06 ` Sean Christopherson
2026-08-11 20:21 ` Paolo Bonzini
2026-08-11 21:14 ` David Woodhouse
2026-08-11 22:58 ` Sean Christopherson
2026-08-11 23:50 ` David Woodhouse
2026-08-12 10:25 ` David Woodhouse
2026-08-11 20:29 ` David Woodhouse
2026-08-11 15:12 ` David Hildenbrand (Arm)
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