From: Jason Gunthorpe <jgg@ziepe.ca>
To: Michal Hocko <mhocko@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org,
"DRI Development" <dri-devel@lists.freedesktop.org>,
"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"David Rientjes" <rientjes@google.com>,
"Christian König" <christian.koenig@amd.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Masahiro Yamada" <yamada.masahiro@socionext.com>,
"Wei Wang" <wvw@google.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Jann Horn" <jannh@google.com>, "Feng Tang" <feng.tang@intel.com>,
"Kees Cook" <keescook@chromium.org>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Daniel Vetter" <daniel.vetter@intel.com>
Subject: Re: [PATCH 2/5] kernel.h: Add non_block_start/end()
Date: Fri, 16 Aug 2019 09:19:06 -0300 [thread overview]
Message-ID: <20190816121906.GC5398@ziepe.ca> (raw)
In-Reply-To: <20190816081029.GA27790@dhcp22.suse.cz>
On Fri, Aug 16, 2019 at 10:10:29AM +0200, Michal Hocko wrote:
> On Thu 15-08-19 17:13:23, Jason Gunthorpe wrote:
> > On Thu, Aug 15, 2019 at 09:35:26PM +0200, Michal Hocko wrote:
> >
> > > > The last detail is I'm still unclear what a GFP flags a blockable
> > > > invalidate_range_start() should use. Is GFP_KERNEL OK?
> > >
> > > I hope I will not make this muddy again ;)
> > > invalidate_range_start in the blockable mode can use/depend on any sleepable
> > > allocation allowed in the context it is called from.
> >
> > 'in the context is is called from' is the magic phrase, as
> > invalidate_range_start is called while holding several different mm
> > related locks. I know at least write mmap_sem and i_mmap_rwsem
> > (write?)
> >
> > Can GFP_KERNEL be called while holding those locks?
>
> i_mmap_rwsem would be problematic because it is taken during the
> reclaim.
Okay.. So the fs_reclaim debugging does catch errors. Do you have any
reference for what a false positive looks like?
I would like to inject it into the notifier path as this is very
difficult for driver authors to discover and know about, but I'm
worried about your false positive remark.
I think I understand we can use only GFP_ATOMIC in the notifiers, but
we need a strategy to handle OOM to guarentee forward progress.
This is just more bugs to fix :(
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@ziepe.ca>
To: Michal Hocko <mhocko@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org,
"DRI Development" <dri-devel@lists.freedesktop.org>,
"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"David Rientjes" <rientjes@google.com>,
"Christian König" <christian.koenig@amd.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Masahiro Yamada" <yamada.masahiro@socionext.com>,
"Wei Wang" <wvw@google.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Jann Horn" <jannh@google.com>, "Feng Tang" <feng.tang@intel.com>,
"Kees Cook" <keescook@chromium.org>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Daniel Vetter" <daniel.vetter@i>
Subject: Re: [PATCH 2/5] kernel.h: Add non_block_start/end()
Date: Fri, 16 Aug 2019 09:19:06 -0300 [thread overview]
Message-ID: <20190816121906.GC5398@ziepe.ca> (raw)
In-Reply-To: <20190816081029.GA27790@dhcp22.suse.cz>
On Fri, Aug 16, 2019 at 10:10:29AM +0200, Michal Hocko wrote:
> On Thu 15-08-19 17:13:23, Jason Gunthorpe wrote:
> > On Thu, Aug 15, 2019 at 09:35:26PM +0200, Michal Hocko wrote:
> >
> > > > The last detail is I'm still unclear what a GFP flags a blockable
> > > > invalidate_range_start() should use. Is GFP_KERNEL OK?
> > >
> > > I hope I will not make this muddy again ;)
> > > invalidate_range_start in the blockable mode can use/depend on any sleepable
> > > allocation allowed in the context it is called from.
> >
> > 'in the context is is called from' is the magic phrase, as
> > invalidate_range_start is called while holding several different mm
> > related locks. I know at least write mmap_sem and i_mmap_rwsem
> > (write?)
> >
> > Can GFP_KERNEL be called while holding those locks?
>
> i_mmap_rwsem would be problematic because it is taken during the
> reclaim.
Okay.. So the fs_reclaim debugging does catch errors. Do you have any
reference for what a false positive looks like?
I would like to inject it into the notifier path as this is very
difficult for driver authors to discover and know about, but I'm
worried about your false positive remark.
I think I understand we can use only GFP_ATOMIC in the notifiers, but
we need a strategy to handle OOM to guarentee forward progress.
This is just more bugs to fix :(
Jason
next prev parent reply other threads:[~2019-08-16 12:19 UTC|newest]
Thread overview: 130+ 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 20:20 ` Daniel Vetter
2019-08-14 20:45 ` Andrew Morton
2019-08-14 20:45 ` Andrew Morton
2019-08-15 6:52 ` Daniel Vetter
2019-08-15 6:52 ` Daniel Vetter
2019-08-15 8:44 ` Michal Hocko
2019-08-15 8:44 ` Michal Hocko
2019-08-15 13:04 ` Jason Gunthorpe
2019-08-15 13:04 ` Jason Gunthorpe
2019-08-15 13:12 ` Daniel Vetter
2019-08-15 13:12 ` Daniel Vetter
2019-08-15 14:37 ` Jason Gunthorpe
2019-08-15 14:37 ` Jason Gunthorpe
2019-08-15 14:43 ` Daniel Vetter
2019-08-15 14:43 ` Daniel Vetter
2019-08-15 15:10 ` Jason Gunthorpe
2019-08-15 15:10 ` Jason Gunthorpe
2019-08-15 16:25 ` Daniel Vetter
2019-08-15 16:25 ` Daniel Vetter
2019-08-15 17:35 ` Jason Gunthorpe
2019-08-15 17:35 ` Jason Gunthorpe
2019-08-15 17:39 ` Jerome Glisse
2019-08-15 17:39 ` Jerome Glisse
2019-08-15 18:01 ` Jason Gunthorpe
2019-08-15 18:01 ` Jason Gunthorpe
2019-08-15 18:27 ` Jerome Glisse
2019-08-15 18:27 ` Jerome Glisse
2019-08-15 18:57 ` Jason Gunthorpe
2019-08-15 18:57 ` Jason Gunthorpe
2019-08-15 16:32 ` Jerome Glisse
2019-08-15 16:32 ` Jerome Glisse
2019-08-15 17:16 ` Jason Gunthorpe
2019-08-15 17:16 ` Jason Gunthorpe
2019-08-15 17:21 ` Daniel Vetter
2019-08-15 17:21 ` Daniel Vetter
2019-08-15 17:35 ` Jerome Glisse
2019-08-15 17:35 ` Jerome Glisse
2019-08-15 13:24 ` Michal Hocko
2019-08-15 13:24 ` Michal Hocko
2019-08-15 22:15 ` Andrew Morton
2019-08-15 22:15 ` Andrew Morton
2019-08-16 8:24 ` Michal Hocko
2019-08-16 8:24 ` Michal Hocko
2019-08-14 23:58 ` Jason Gunthorpe
2019-08-14 23:58 ` Jason Gunthorpe
2019-08-15 6:58 ` Daniel Vetter
2019-08-15 6:58 ` Daniel Vetter
2019-08-15 12:23 ` Jason Gunthorpe
2019-08-15 12:23 ` Jason Gunthorpe
2019-08-15 13:21 ` Michal Hocko
2019-08-15 13:21 ` Michal Hocko
2019-08-15 14:12 ` Jason Gunthorpe
2019-08-15 14:12 ` Jason Gunthorpe
2019-08-15 16:00 ` Michal Hocko
2019-08-15 16:00 ` Michal Hocko
2019-08-15 16:56 ` Jason Gunthorpe
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 17:42 ` Michal Hocko
2019-08-15 17:57 ` Jerome Glisse
2019-08-15 18:24 ` Jason Gunthorpe
2019-08-15 18:24 ` Jason Gunthorpe
2019-08-15 19:05 ` Michal Hocko
2019-08-15 19:05 ` Michal Hocko
2019-08-15 19:18 ` Jason Gunthorpe
2019-08-15 19:18 ` Jason Gunthorpe
2019-08-15 19:35 ` Michal Hocko
2019-08-15 19:35 ` Michal Hocko
2019-08-15 20:13 ` Jason Gunthorpe
2019-08-15 20:13 ` Jason Gunthorpe
2019-08-16 8:10 ` Michal Hocko
2019-08-16 8:10 ` Michal Hocko
2019-08-16 12:19 ` Jason Gunthorpe [this message]
2019-08-16 12:19 ` Jason Gunthorpe
2019-08-16 12:26 ` Michal Hocko
2019-08-16 12:26 ` Michal Hocko
2019-08-16 14:31 ` Jason Gunthorpe
2019-08-16 14:31 ` Jason Gunthorpe
2019-08-16 15:05 ` Jerome Glisse
2019-08-16 15:05 ` Jerome Glisse
2019-08-20 8:18 ` Michal Hocko
2019-08-20 8:18 ` Michal Hocko
2019-08-15 20:16 ` [Intel-gfx] " Daniel Vetter
2019-08-15 20:16 ` Daniel Vetter
2019-08-15 20:27 ` Jason Gunthorpe
2019-08-15 20:27 ` Jason Gunthorpe
2019-08-15 20:49 ` Daniel Vetter
2019-08-15 20:49 ` Daniel Vetter
2019-08-16 1:00 ` Jason Gunthorpe
2019-08-16 1:00 ` Jason Gunthorpe
2019-08-16 6:20 ` Daniel Vetter
2019-08-16 6:20 ` Daniel Vetter
2019-08-16 12:12 ` Jason Gunthorpe
2019-08-16 12:12 ` Jason Gunthorpe
2019-08-16 14:11 ` Daniel Vetter
2019-08-16 14:11 ` Daniel Vetter
2019-08-16 14:38 ` Jason Gunthorpe
2019-08-16 14:38 ` Jason Gunthorpe
2019-08-16 16:36 ` Daniel Vetter
2019-08-16 16:36 ` Daniel Vetter
2019-08-16 16:54 ` Jason Gunthorpe
2019-08-16 16:54 ` Jason Gunthorpe
2019-08-16 8:27 ` Michal Hocko
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
2019-08-15 12:35 ` Jason Gunthorpe
2019-08-17 16:09 ` Daniel Vetter
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 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
2019-08-15 7:14 ` Daniel Vetter
2019-08-14 21:29 ` ✗ Fi.CI.CHECKPATCH: warning for hmm & mmu_notifier debug/lockdep annotations Patchwork
2019-08-14 21:56 ` ✓ Fi.CI.BAT: success " Patchwork
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