From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793093628; b=iLbwdxLX+SVq/KRI89SgaPe+x29zfuSdkbXRVBjbpIeIj9wi4ibjSkEKSv2sqyFJIHcl 4/E3e3P2VqfFZ5UvAum5rtWqHqEd8kDrA2ohOj20CUUVNOeKF7Tjwe2pKf5uHit+4mvUp ZDo2eCTo2hQHqybxxYKxN/vejPfKluv6yeGAnpo6vrAGtw1o3fE1EsXqeHWldVnjsYYlR YmJGW60P91+9sbo6q+UGHOG2kjMPsir7XML1cexc+lnclrV20w1Q+EMnDGJRw0IQUEbPF 26GBk+L+NX9Zn6rt8fpb/3HbHhdsA4NL5XFVAfQ4fHpMpY+SnQhCBY+wzYmkTb9p0FQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793093628; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=gIudMcxLM3PAXcDR9AP1Q8SoYHkkEJyeOudQMB7zZi4=; b=Bbs7jjoyhXhCZ/SRTSY5T/+WZnwv0TEU08NmtdgeT10xelAapNgJPWzd86moOp9DYMc4 R89WD3MiKXgbOUPXdAZT/1Cll6ThQziXHU5vN73xTb5IgBvfHsb+cshlrcPfXPZnk+UlK ggZmSV0ctwxGdYw29p+ZU5dOcTCuhcsQ80CGTOq1N37xkflWPiEfxeGzh99eYtQVnMjYQ s4vPsfvllOXaCG8ElP4hhBqmuJJIV5i3NZh56BQ/EzVD/GSXdZmR8JPr/bKUEc+TWwudM OP/vCiAdhsE4Fc4D1LErc1ojKQVF3YuP4ZQFqxRLfLEl3iZEerGIRj3iix1XfrM2AtA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=oKfzWY26; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DAF6F606A31A; Tue, 27 Oct 2026 09:33:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=oKfzWY26 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 095811F031E4; Tue, 27 Oct 2026 09:33:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793093627; bh=gIudMcxLM3PAXcDR9AP1Q8SoYHkkEJyeOudQMB7zZi4=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=oKfzWY26WKA+bbXl616ae0oQzbA1G0xH9l9xh1gCxq3JDpe8yv97IXYdyOfHQ4eJr t81Po39gxIf/641f8WvuMrH0lH9eqiO320Dz8AtVuz8iZU3projZTXWMccoEocNd/6 dh/GTbiarJBXfnd4LASC1pYnYHmLhWpnrmbzH4mHnkutHY5LYB08EzCW/mDgGMPsGa qOAll772fgvtDpz0InhCuO+wST7Gz+w1BkWkocfnh9yOov6hzmvFdgw6+D2H+bUwyj Zopnno5uue65TWC1px1FoMLDq3bw/n2ASl+8B3UapPHEfEcHiQNOqE7pRfjn9OD0/j SZDcHaIh8SkjQ== Date: Tue, 27 Oct 2026 09:33:31 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Josef Bacik , stable@vger.kernel.org Subject: Re: [PATCH 27/46] mm/mmu_notifier: finish non-blocking interval invalidation on error Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-27-6f74bec9a5bb@kernel.org> X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-27-6f74bec9a5bb@kernel.org> On Tue, Oct 27, 2026 at 12:17:47AM +0100, David Hildenbrand (Arm) wrote: > From: Josef Bacik > > When an ordinary MMU notifier rejects a non-blocking invalidation, the > interval invalidation started beforehand is left unfinished: the caller > skips mmu_notifier_invalidate_range_end(). Subsequent interval notifier > operations can then wait forever. > > The only in-tree trigger is nouveau SVM, which uses both notifier types > and rejects non-blocking invalidations. Reaping via the OOM reaper or > process_mrelease() can therefore leave the GPU fault worker stuck, > holding a reference that prevents the dying process's address space > and memory from being freed. > > End the interval invalidation when an ordinary notifier fails a > non-blocking invalidation, like mn_itree_invalidate() already does when > an interval notifier fails. Make that handling clearer in the > documentation of mmu_notifier_invalidate_range_start_nonblock(). > > Fix generated by an LLM and sent by Josef Bacik in private. > > Fixes: 99cb252f5e68 ("mm/mmu_notifier: add an interval tree notifier") > Cc: stable@vger.kernel.org > Signed-off-by: Josef Bacik > [ david: simplify description, update function doc ] > Signed-off-by: David Hildenbrand (Arm) Acked-by: Lorenzo Stoakes (ARM) > --- > include/linux/mmu_notifier.h | 3 ++- > mm/mmu_notifier.c | 17 +++++++++++++---- > 2 files changed, 15 insertions(+), 5 deletions(-) > > diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h > index a11a44eef521e..5db78e5761c5c 100644 > --- a/include/linux/mmu_notifier.h > +++ b/include/linux/mmu_notifier.h > @@ -483,7 +483,8 @@ mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range) > /* > * This version of mmu_notifier_invalidate_range_start() avoids blocking, but it > * can return an error if a notifier can't proceed without blocking, in which > - * case you're not allowed to modify PTEs in the specified range. > + * case you're not allowed to modify PTEs in the specified range or call > + * mmu_notifier_invalidate_range_end(). > * > * This is mainly intended for OOM handling. > */ > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index df69ba6e797f7..2e20f88e162d7 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -569,16 +569,25 @@ int __mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range) > { > struct mmu_notifier_subscriptions *subscriptions = > range->mm->notifier_subscriptions; > - int ret; > + const bool has_itree = subscriptions->has_itree; > + int ret = 0; > > - if (subscriptions->has_itree) { > + if (has_itree) { > ret = mn_itree_invalidate(subscriptions, range); > if (ret) > return ret; > } > if (!hlist_empty(&subscriptions->list)) > - return mn_hlist_invalidate_range_start(subscriptions, range); > - return 0; > + ret = mn_hlist_invalidate_range_start(subscriptions, range); > + > + /* > + * On error, the non-blocking caller is not allowed to call > + * invalidate_range_end(), as in mn_itree_invalidate(). > + */ > + if (ret && has_itree && !mmu_notifier_range_blockable(range)) > + mn_itree_inv_end(subscriptions); > + > + return ret; > } > > static void > > -- > 2.43.0 > -- Cheers, Lorenzo