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Fri, 10 Jul 2026 09:44:29 -0700 (PDT) Received: from ziepe.ca ([159.2.72.92]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ffd56c4b91sm45168766d6.19.2026.07.10.09.44.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jul 2026 09:44:28 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wiEKx-00000007Yxj-3wpY; Fri, 10 Jul 2026 13:44:27 -0300 Date: Fri, 10 Jul 2026 13:44:27 -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 8/8] drm/gpusvm: Use hmm_range_fault_unlocked_timeout() for range faults Message-ID: <20260710164427.GW118978@ziepe.ca> References: <178345345668.660027.2952911919681614557.stgit@skinsburskii> <178345366389.660027.12986386801605494596.stgit@skinsburskii> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <178345366389.660027.12986386801605494596.stgit@skinsburskii> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 21C7E120008 X-Stat-Signature: rfjdocwqi186b1y81jf14a6x5j95b41m X-HE-Tag: 1783701869-492093 X-HE-Meta: U2FsdGVkX1+Y9EkG7PoO+AYeNE9Biud3FD5IpuNEVd88njkjrEX9Zf9lo6lGu+wI5dTVenUrtTIhdGMUHFbRPClqPz6dGPpB8rR5UDf0smwtVGeyWJE5Wt3nlP7P01HeWUXzN7BIEwv1lonNcT2woMPN7OBLLanO/i/4xPVCaShmaO+QSmbBgm3nrYyZ3pYvRptOR8m1W5sv78qUGy2yVJmib6xfbNU4PO6xdtDxM7VQS1G5FwZfjEDFeIMUJN/c0cbXzTcY7Ji/0eFEh3ejmai/IfF5L5m+WTmjZQ4NB58kzLN0qbt/8jMxtjaeS3hYM17Ihldi+TOepraQSHwpZXo+P9uPYpCx30DDpYkmHAjVNZswf3+wvfHoSKRN8HnQaENa7wPenixnug3mtpatwBjEFxuNd+DJBOe21GHbeVyrIdVRYF2GvarClv/VNeFGtlGMw2tOPO9WGxc+rSsCin0t7mo/jcoIhBBSSn08Sd7J4IHfl9QJEBc0Tfw/nqkGYrXWZU6yEnR6I8rJsENuXXIw1CVfq7vivBQS0Ss2Ak3C2GBSmJwoi+XHPSkcejGtD3qU7Ivr868p/wLE7PBH3DwR+PGdCa6yV1KXk1LiPfqT3BY13aM+UzYvJK6f+lWqa6hrBx51hbvYC2Y4sZkweLpB/BlZKK34dboNHta0tUN/mnm9wXHWJ9ZvygkYt5Ba0QCX958L+yK0flcoeLv2catEMTJ7uSsu1at4iFmOxMmu+cxsKoQPdPjsGYFegdhLH6Gba1W8tHORsbANWm0cEPuf/2pKV0AdX66qXwu5fXnbdsakKc60JaC1ic0nptLHOvRqOBqFfITaVOjWN3hE4hUO37J1b1+n1oXIvy7YBaYaorrzM6gLe8QoANMoWNcFX1wbK3kjNYvEqsML7WNPVHB6M06LBrstwlYNoGJ23QihaI2cFMFd3vmLQS0ZTWTSS50njVBixxokZrelPzO r3OH+Ytl jmYBDkUbzA76tevdWD5qT+8zO5+zpHUya29NSh5c9ke7AVExQRVU9mhEwS/Si4Mb+SFJQHUqS6QxHLNRm4oli8EMxPASQKmxne+7mWKItDm3UHAVAO5bgBZlZdJCLNaHkiCo/xs3804XOKT6/+76b3qJPGVMtmrbJaeqvGNaKnA30SLPzWP5NIVIv77PrF7ZBlNw0ucmVNvZPAQrDgA8aguS8popfBHre5pWu3vpjtwNXBhTL19t58DiUz2ztMAcYZt5VJa0ALcW1rya5uF8bkz0CXsAgOijWAr0GJoZIgX6LZ1r5M62M22mfH/nnKChpiDXZxfs042ptofvKSphwzlel8ClkgH2U4WpZcMkyIlE6XtnXww4qDVzg63JEfUhnV0jk 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 12:47:43PM -0700, Stanislav Kinsburskii wrote: > Several GPU SVM paths take mmap_read_lock() only to call hmm_range_fault(), > then retry -EBUSY until HMM_RANGE_DEFAULT_TIMEOUT expires. Those paths use > MMU interval notifiers whose mm matches the mm that was locked for the HMM > fault. > > Use hmm_range_fault_unlocked_timeout() for those faults and pass the > remaining retry budget to HMM. The helper owns mmap_lock acquisition and > refreshes range->notifier_seq internally for each retry, while GPU SVM > keeps its existing driver-lock validation with mmu_interval_read_retry() > after a successful fault. > > Leave drm_gpusvm_check_pages() on hmm_range_fault() because that path is > called with the mmap lock already held by its caller. > > Signed-off-by: Stanislav Kinsburskii > --- > drivers/gpu/drm/drm_gpusvm.c | 52 ++++++------------------------------------ > 1 file changed, 7 insertions(+), 45 deletions(-) Reviewed-by: Jason Gunthorpe > - mmap_read_unlock(range->gpusvm->mm); > + err = hmm_range_fault_unlocked_timeout(&hmm_range, > + max_t(long, timeout - jiffies, 1)); Same remark about max_t Jason