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[156.34.55.100]) by smtp.gmail.com with ESMTPSA id m129sm2560940qkf.86.2019.08.20.06.31.35 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 20 Aug 2019 06:31:35 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1i04EZ-0000YV-7s; Tue, 20 Aug 2019 10:31:35 -0300 Date: Tue, 20 Aug 2019 10:31:35 -0300 From: Jason Gunthorpe To: Daniel Vetter Cc: LKML , Linux MM , DRI Development , Intel Graphics Development , Chris Wilson , Andrew Morton , David Rientjes , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Michal Hocko , Christian =?utf-8?B?S8O2bmln?= , Greg Kroah-Hartman , Mike Rapoport , Daniel Vetter Subject: Re: [PATCH 2/4] mm, notifier: Prime lockdep Message-ID: <20190820133135.GF29246@ziepe.ca> References: <20190820081902.24815-1-daniel.vetter@ffwll.ch> <20190820081902.24815-3-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190820081902.24815-3-daniel.vetter@ffwll.ch> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 20, 2019 at 10:19:00AM +0200, Daniel Vetter wrote: > We want to teach lockdep that mmu notifiers can be called from direct > reclaim paths, since on many CI systems load might never reach that > level (e.g. when just running fuzzer or small functional tests). > > Motivated by a discussion with Jason. > > I've put the annotation into mmu_notifier_register since only when we > have mmu notifiers registered is there any point in teaching lockdep > about them. Also, we already have a kmalloc(, GFP_KERNEL), so this is > safe. > > Cc: Jason Gunthorpe > Cc: Chris Wilson > Cc: Andrew Morton > Cc: David Rientjes > Cc: "Jérôme Glisse" > Cc: Michal Hocko > Cc: "Christian König" > Cc: Greg Kroah-Hartman > Cc: Daniel Vetter > Cc: Mike Rapoport > Cc: linux-mm@kvack.org > Signed-off-by: Daniel Vetter > mm/mmu_notifier.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index d12e3079e7a4..538d3bb87f9b 100644 > +++ b/mm/mmu_notifier.c > @@ -256,6 +256,13 @@ static int do_mmu_notifier_register(struct mmu_notifier *mn, > > BUG_ON(atomic_read(&mm->mm_users) <= 0); > > + if (IS_ENABLED(CONFIG_LOCKDEP)) { > + fs_reclaim_acquire(GFP_KERNEL); > + lock_map_acquire(&__mmu_notifier_invalidate_range_start_map); > + lock_map_release(&__mmu_notifier_invalidate_range_start_map); > + fs_reclaim_release(GFP_KERNEL); > + } Lets try it out at least Reviewed-by: Jason Gunthorpe Jason