From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 98204C531D0 for ; Thu, 23 Jul 2026 21:22:49 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 752FB6B007B; Thu, 23 Jul 2026 17:22:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7035C6B0088; Thu, 23 Jul 2026 17:22:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5F4966B008A; Thu, 23 Jul 2026 17:22:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 35DAE6B007B for ; Thu, 23 Jul 2026 17:22:48 -0400 (EDT) Received: from smtpin03.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id B4E36A0899 for ; Thu, 23 Jul 2026 21:22:47 +0000 (UTC) X-FDA: 85021315974.03.C327240 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf24.hostedemail.com (Postfix) with ESMTP id 02EF8180005 for ; Thu, 23 Jul 2026 21:22:45 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=PqDGtK1y; spf=pass (imf24.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784841766; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=8LsF46xxakxlsARFJxGTWxEVy+kM0PIVoXm+jBklc8Q=; b=pv6G3qIfu21V3Gsda9mqDb9pSuP7ETRiXGfMzxqkXyZLI5qlPywoqDcgg8FIlz1hFjJjHP O9mG6xUpSCbpKX8eYD7/YGEAhdvVWyPxJwpdN4iHeXMza5wGK6LLMlDSpWxOnwoE2RKTrp sacosyxFfj6Q7I3YRO7FBe2YCx6X/eI= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784841766; b=UQuofJTRoWV673mKTiZHOuYlPWaEYYFGDUWX+K0GEoN3VfKYw+XKTYSIF3dp0n0Xe+Lc7w pt+YFcsXZQ6wNmnAykLOSgSvgTqUpqqnS6vWNpsqkuuy2tqDxSosCsJ5mDi5PzLqtuPblR fjfm+oTF9KoCF/h+lCgLH//dspaz4OM= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=PqDGtK1y; spf=pass (imf24.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 738B8408E9; Thu, 23 Jul 2026 21:22:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31E381F000E9; Thu, 23 Jul 2026 21:22:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1784841764; bh=8LsF46xxakxlsARFJxGTWxEVy+kM0PIVoXm+jBklc8Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=PqDGtK1ymZc6iwXzb09CtmFYmLViI3ZUzwC4EZJzeq9zwSf91u2vNh/4wCIJIHPWO e15iO8gkDRLbbRBA2tojf2jKWmot7imPS0HbTnDJI9D1VtypOpQwHATciE7rioefeK s0fKBNhwMPvzspt/Hs40GfWyqW0dMZJpQhg7C0tk= Date: Thu, 23 Jul 2026 14:22:42 -0700 From: Andrew Morton To: Stanislav Kinsburskii Cc: Jason Gunthorpe , Leon Romanovsky , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan , Shuah Khan , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Lyude Paul , Danilo Krummrich , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Min Ma , Lizhi Hou , Oded Gabbay , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-rdma@vger.kernel.org Subject: Re: [PATCH v11 0/8] mm/hmm: Add mmap lock-drop support for userfaultfd-backed mappings Message-Id: <20260723142242.5d3f87208d47819d873ae458@linux-foundation.org> In-Reply-To: <20260723-hmm-v10-v11-0-c55b003a4b61@gmail.com> References: <20260723-hmm-v10-v11-0-c55b003a4b61@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 02EF8180005 X-Stat-Signature: u6wnan9ptdm8uh53uu1pm15smxrb5g6f X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1784841765-618278 X-HE-Meta: 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 WyO+EKxD Mf1SeUh5vQW3czLyMTc4d4KKuK4xJjmRWEVf5o/DPjMnLwsC7+20OwKB8M/eZF/WCs7BvuHDQ1fCAlRGuOSn/seIzUMfqT2v7UHqKIWMpk3wGaRR/bO+XfeORLAnMlnPL5+1q67ssFadHSgc0IOrAlZk/dZdlGPv0M63o2QqVs7p45a0jYWzZ+nQJJncReuhYixVn+hrdGIWwWCbgJhKMmbnc/fsFp+9hnByu7Jr+9+gbXHQWrfLxaOgGZP7wZyaH0rz027Fr3DJa3AfBFPTD3LoxSpVS13Qq/6CXHNXgf4CF0MYwskfkFlWAiM4txlW1M1e95tg+CAJy3A3IuhcP8fHCJg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 23 Jul 2026 10:36:32 -0700 Stanislav Kinsburskii wrote: > This series extends the HMM framework to support userfaultfd-backed memory > by allowing the mmap read lock to be dropped during hmm_range_fault(). > Thanks, I've updated mm.git to this version. AI review suggests there may be some problems. Sorry, I don't recall if these were considered in previous versions of the patchset: https://sashiko.dev/#/patchset/20260723-hmm-v10-v11-0-c55b003a4b61@gmail.com > > Changes in v11: > - Reject unstable address spaces in hmm_range_fault_unlocked_timeout() > after taking mmap_lock and before walking page tables. > - Compute the remaining HMM timeout budget before the time_after_eq() > check in drm_gpusvm_get_pages() to make sure it can't result in zero > and lead to infinite HMM range faulting loop. Here's how v11 altered mm.git: drivers/gpu/drm/drm_gpusvm.c | 4 ++-- mm/hmm.c | 6 ++++++ 2 files changed, 8 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/drm_gpusvm.c~b +++ a/drivers/gpu/drm/drm_gpusvm.c @@ -1422,11 +1422,11 @@ int drm_gpusvm_get_pages(struct drm_gpus struct dma_iova_state *state = &svm_pages->state; retry: + remaining = timeout - jiffies; + if (time_after_eq(jiffies, timeout)) return -EBUSY; - remaining = timeout - jiffies; - hmm_range.notifier_seq = mmu_interval_read_begin(notifier); if (drm_gpusvm_pages_valid_unlocked(gpusvm, svm_pages)) goto set_seqno; --- a/mm/hmm.c~b +++ a/mm/hmm.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -806,6 +807,11 @@ int hmm_range_fault_unlocked_timeout(str if (ret) return ret; + if (check_stable_address_space(mm)) { + mmap_read_unlock(mm); + return -EFAULT; + } + if (timeout && time_after(jiffies, deadline)) { mmap_read_unlock(mm); return -EBUSY; _