From: Daniel Vetter <daniel@ffwll.ch>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: "Michal Hocko" <mhocko@kernel.org>,
"Feng Tang" <feng.tang@intel.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Kees Cook" <keescook@chromium.org>,
"Masahiro Yamada" <yamada.masahiro@socionext.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
"Jann Horn" <jannh@google.com>,
LKML <linux-kernel@vger.kernel.org>,
"DRI Development" <dri-devel@lists.freedesktop.org>,
"Linux MM" <linux-mm@kvack.org>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"David Rientjes" <rientjes@google.com>,
"Wei Wang" <wvw@google.com>,
"Daniel Vetter" <daniel.vetter@intel.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Christian König" <christian.koenig@amd.com>
Subject: Re: [Intel-gfx] [PATCH 2/5] kernel.h: Add non_block_start/end()
Date: Fri, 16 Aug 2019 08:20:55 +0200 [thread overview]
Message-ID: <CAKMK7uH0oa10LoCiEbj1NqAfWitbdOa-jQm9hM=iNL-=8gH9nw@mail.gmail.com> (raw)
In-Reply-To: <20190816010036.GA9915@ziepe.ca>
On Fri, Aug 16, 2019 at 3:00 AM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> On Thu, Aug 15, 2019 at 10:49:31PM +0200, Daniel Vetter wrote:
> > On Thu, Aug 15, 2019 at 10:27 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > > On Thu, Aug 15, 2019 at 10:16:43PM +0200, Daniel Vetter wrote:
> > > > So if someone can explain to me how that works with lockdep I can of
> > > > course implement it. But afaics that doesn't exist (I tried to explain
> > > > that somewhere else already), and I'm no really looking forward to
> > > > hacking also on lockdep for this little series.
> > >
> > > Hmm, kind of looks like it is done by calling preempt_disable()
> >
> > Yup. That was v1, then came the suggestion that disabling preemption
> > is maybe not the best thing (the oom reaper could still run for a long
> > time comparatively, if it's cleaning out gigabytes of process memory
> > or what not, hence this dedicated debug infrastructure).
>
> Oh, I'm coming in late, sorry
>
> Anyhow, I was thinking since we agreed this can trigger on some
> CONFIG_DEBUG flag, something like
>
> /* This is a sleepable region, but use preempt_disable to get debugging
> * for calls that are not allowed to block for OOM [.. insert
> * Michal's explanation.. ] */
> if (IS_ENABLED(CONFIG_DEBUG_ATOMIC_SLEEP) && !mmu_notifier_range_blockable(range))
> preempt_disable();
> ops->invalidate_range_start();
I think we also discussed that, and some expressed concerns it would
change behaviour/timing too much for testing. Since this does does
disable preemption for real, not just for might_sleep.
> And I have also been idly mulling doing something like
>
> if (IS_ENABLED(CONFIG_DEBUG_NOTIFIERS) &&
> rand &&
> mmu_notifier_range_blockable(range)) {
> range->flags = 0
> if (!ops->invalidate_range_start(range))
> continue
>
> // Failed, try again as blockable
> range->flags = MMU_NOTIFIER_RANGE_BLOCKABLE
> }
> ops->invalidate_range_start(range);
>
> Which would give coverage for this corner case without forcing OOM.
Hm, this sounds like a neat idea to slap on top. The rand is going to
be a bit tricky though, but I guess for this we could stuff another
counter into task_struct and just e.g. do this every 1000th or so
invalidate (well need to pick a prime so we cycle through notifiers in
case there's multiple). I like.
Michal, thoughts?
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
next prev parent reply other threads:[~2019-08-16 6:21 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-14 20:20 [PATCH 0/5] hmm & mmu_notifier debug/lockdep annotations Daniel Vetter
2019-08-14 20:20 ` [PATCH 1/5] mm: Check if mmu notifier callbacks are allowed to fail Daniel Vetter
2019-08-14 22:14 ` Andrew Morton
2019-08-14 23:22 ` Jason Gunthorpe
2019-08-14 23:34 ` Ralph Campbell
2019-08-16 17:19 ` Jason Gunthorpe
2019-08-14 20:20 ` [PATCH 2/5] kernel.h: Add non_block_start/end() Daniel Vetter
2019-08-14 20:45 ` Andrew Morton
2019-08-15 6:52 ` Daniel Vetter
2019-08-15 8:44 ` Michal Hocko
2019-08-15 13:04 ` Jason Gunthorpe
2019-08-15 13:12 ` Daniel Vetter
2019-08-15 14:37 ` Jason Gunthorpe
2019-08-15 14:43 ` Daniel Vetter
2019-08-15 15:10 ` Jason Gunthorpe
2019-08-15 16:25 ` Daniel Vetter
2019-08-15 17:35 ` Jason Gunthorpe
2019-08-15 17:39 ` Jerome Glisse
2019-08-15 18:01 ` Jason Gunthorpe
2019-08-15 18:27 ` Jerome Glisse
2019-08-15 18:57 ` Jason Gunthorpe
2019-08-15 16:32 ` Jerome Glisse
2019-08-15 17:16 ` Jason Gunthorpe
2019-08-15 17:21 ` Daniel Vetter
2019-08-15 17:35 ` Jerome Glisse
2019-08-15 13:24 ` Michal Hocko
2019-08-15 22:15 ` Andrew Morton
2019-08-16 8:24 ` Michal Hocko
2019-08-14 23:58 ` Jason Gunthorpe
2019-08-15 6:58 ` Daniel Vetter
2019-08-15 12:23 ` Jason Gunthorpe
2019-08-15 13:21 ` Michal Hocko
2019-08-15 14:12 ` Jason Gunthorpe
2019-08-15 16:00 ` Michal Hocko
2019-08-15 16:56 ` Jason Gunthorpe
2019-08-15 17:11 ` Jerome Glisse
2019-08-15 17:17 ` Jason Gunthorpe
2019-08-15 17:42 ` Michal Hocko
2019-08-15 17:57 ` Jerome Glisse
2019-08-15 18:24 ` Jason Gunthorpe
2019-08-15 19:05 ` Michal Hocko
2019-08-15 19:18 ` Jason Gunthorpe
2019-08-15 19:35 ` Michal Hocko
2019-08-15 20:13 ` Jason Gunthorpe
2019-08-16 8:10 ` Michal Hocko
2019-08-16 12:19 ` Jason Gunthorpe
2019-08-16 12:26 ` Michal Hocko
2019-08-15 20:16 ` [Intel-gfx] " Daniel Vetter
2019-08-15 20:27 ` Jason Gunthorpe
2019-08-15 20:49 ` Daniel Vetter
2019-08-16 1:00 ` Jason Gunthorpe
2019-08-16 6:20 ` Daniel Vetter [this message]
2019-08-16 12:12 ` Jason Gunthorpe
2019-08-16 14:11 ` Daniel Vetter
2019-08-16 14:38 ` Jason Gunthorpe
2019-08-16 16:36 ` Daniel Vetter
2019-08-16 16:54 ` Jason Gunthorpe
2019-08-16 8:27 ` Michal Hocko
2019-08-14 20:20 ` [PATCH 3/5] mm, notifier: Catch sleeping/blocking for !blockable Daniel Vetter
2019-08-15 0:00 ` Jason Gunthorpe
2019-08-15 7:02 ` Daniel Vetter
[not found] ` <20190815123556.GB21596@ziepe.ca>
2019-08-17 16:09 ` Daniel Vetter
2019-08-14 20:20 ` [PATCH 4/5] mm, notifier: Add a lockdep map for invalidate_range_start Daniel Vetter
2019-08-15 0:09 ` Jason Gunthorpe
2019-08-15 7:10 ` Daniel Vetter
2019-08-15 12:53 ` Jason Gunthorpe
2019-08-14 20:20 ` [PATCH 5/5] mm/hmm: WARN on illegal ->sync_cpu_device_pagetables errors Daniel Vetter
2019-08-15 0:11 ` Jason Gunthorpe
2019-08-15 7:14 ` Daniel Vetter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAKMK7uH0oa10LoCiEbj1NqAfWitbdOa-jQm9hM=iNL-=8gH9nw@mail.gmail.com' \
--to=daniel@ffwll.ch \
--cc=akpm@linux-foundation.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=christian.koenig@amd.com \
--cc=daniel.vetter@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=feng.tang@intel.com \
--cc=intel-gfx@lists.freedesktop.org \
--cc=jannh@google.com \
--cc=jgg@ziepe.ca \
--cc=jglisse@redhat.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rdunlap@infradead.org \
--cc=rientjes@google.com \
--cc=tglx@linutronix.de \
--cc=wvw@google.com \
--cc=yamada.masahiro@socionext.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).