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Fri, 10 Jul 2026 09:41:00 -0700 (PDT) Received: from ziepe.ca ([159.2.72.92]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ffd50e0347sm45334476d6.2.2026.07.10.09.40.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jul 2026 09:40:59 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wiEHb-00000007Yc5-1TXt; Fri, 10 Jul 2026 13:40:59 -0300 Date: Fri, 10 Jul 2026 13:40:59 -0300 From: Jason Gunthorpe To: Stanislav Kinsburskii Cc: airlied@gmail.com, akhilesh@ee.iitb.ac.in, akpm@linux-foundation.org, corbet@lwn.net, dakr@kernel.org, david@kernel.org, decui@microsoft.com, haiyangz@microsoft.com, kees@kernel.org, kys@microsoft.com, leon@kernel.org, liam@infradead.org, lizhi.hou@amd.com, ljs@kernel.org, longli@microsoft.com, lyude@redhat.com, maarten.lankhorst@linux.intel.com, mamin506@gmail.com, mhocko@suse.com, mripard@kernel.org, nouveau@lists.freedesktop.org, ogabbay@kernel.org, oleg@redhat.com, rppt@kernel.org, shuah@kernel.org, simona@ffwll.ch, skhan@linuxfoundation.org, surenb@google.com, tzimmermann@suse.de, vbabka@kernel.org, wei.liu@kernel.org, dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH v7 5/8] drm/nouveau: Use hmm_range_fault_unlocked_timeout() for SVM faults Message-ID: <20260710164059.GT118978@ziepe.ca> References: <178345345668.660027.2952911919681614557.stgit@skinsburskii> <178345364273.660027.15274510603185163961.stgit@skinsburskii> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <178345364273.660027.15274510603185163961.stgit@skinsburskii> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5DE5B18000E X-Stat-Signature: 3mt31kpto33kx8iqyju6yrwmn1ehs8kn X-Rspam-User: X-HE-Tag: 1783701661-369868 X-HE-Meta: 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 gVIUQKwb OPtxojdTrLDoveaGxZLIloTHRfNsT+XCf3RL1lqzRdhXr7Vk6Fj7mg1gAJ3woZ71JMiFlwz8G8osBpxRf+YFqxz06ETo2+tRqrD9S3cPHaL8v5LOQecHFscK1dWU9T7clqXA80F20HfjW1DB1tGotISmz1kFPFC4znOGoxr2wDLcVLYbo9IYC9a99ZXIGPcVneYLpsr3FN/t2XaPaFA0eRNELQ1EmC5LlMwV5jnJfhgyewjayQj7wmqFD/kwILSeqSBdYWNd6BAlyKeETQeY26e/e5J5J/oQgNk9/chCFlsIahl5K1qqIKLuhOwUpzQJdNEmBJOVShTGQckuFgPrzSTz5m8R5unSv3maCNwh9rm/BRKXCYxuMeG8Ca3fa9+jlOSJc Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jul 07, 2026 at 12:47:22PM -0700, Stanislav Kinsburskii wrote: > nouveau_range_fault() takes mmap_read_lock() only to call > hmm_range_fault(). It also keeps a single HMM_RANGE_DEFAULT_TIMEOUT > deadline across both HMM -EBUSY retries and post-fault > mmu_interval_read_retry() retries. > > Use hmm_range_fault_unlocked_timeout() instead. The HMM helper now owns > the mmap lock and refreshes range->notifier_seq for its internal retries. > Nouveau keeps its existing absolute deadline in the outer loop and passes > the remaining jiffies to the helper for each fault attempt, so retries > caused by mmu_interval_read_retry() do not reset the overall retry budget. > > Nouveau still validates the interval notifier sequence while holding > svmm->mutex before programming the GPU mapping. > > Signed-off-by: Stanislav Kinsburskii > --- > drivers/gpu/drm/nouveau/nouveau_svm.c | 11 +++-------- > 1 file changed, 3 insertions(+), 8 deletions(-) Reviewed-by: Jason Gunthorpe > - range.notifier_seq = mmu_interval_read_begin(range.notifier); > - mmap_read_lock(mm); > - ret = hmm_range_fault(&range); > - mmap_read_unlock(mm); > - if (ret) { > - if (ret == -EBUSY) > - continue; > + ret = hmm_range_fault_unlocked_timeout(&range, > + max_t(long, timeout - jiffies, 1UL)); Avoid max_t, 1L should be a signed long. Though I'm even more concerned about the timeout if drivers are now wrapping the whole thing in a timeout... That's not sensible at all Jason