From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5C49256D for ; Sun, 12 Jan 2025 09:16:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736673420; cv=none; b=BYV6Uj6yebPLPKMicvJCmAESpx0v0yx7wpK+FiT3IGmXRB33LyjO/IYYuGMy3u5uN8Dx5DwAjiozYZrWenP9pzUeZSG55ieKGbZA07SirnScm6+PiPNLHroskRsVBVM2zTfMmMBkijdH9gKa8j0w8BuHrvBWL04BTbz8SXBVQ14= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736673420; c=relaxed/simple; bh=g4JfB85ZkCK7vnw/krWMg7E1387dEgu//AQ73Q35QEk=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=ighq92t1aaS0Dmetdj/JFg6vUxp4bcXJh3inNF9Ll98u7LPbU2zFQxxSf98teouoAXOKDijgY5XdYgguWezPF2U9nvAZm0ayFz36qsDL6j4p/BzVH6qApofc1axj7UoiBG6xQCZ2g0Gcwvxz60QB2AyvH1vhCfAUtVnbC6Jjm6I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YWrCy4oe; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="YWrCy4oe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1424BC4CEDF; Sun, 12 Jan 2025 09:16:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1736673419; bh=g4JfB85ZkCK7vnw/krWMg7E1387dEgu//AQ73Q35QEk=; h=Subject:To:Cc:From:Date:From; b=YWrCy4oevs4IaD1rOHlVSHqeBe69iETjns6DjjjJd+FryZ8dpZibwUO4d2UwrTRB6 g4Ty4Kiksl+HTYEDtqkyko+TzXtN3sV4kt+sU1+B+GUA6uVym/oVssM3loIxEErJKC PVeB3uQkIRfYqseIWkAKwt9wjvfR1zqo3uVhCfEM= Subject: FAILED: patch "[PATCH] io_uring/eventfd: ensure io_eventfd_signal() defers another" failed to apply to 6.1-stable tree To: axboe@kernel.dk,jannh@google.com,lizetao1@huawei.com,ptsm@linux.microsoft.com Cc: From: Date: Sun, 12 Jan 2025 10:16:46 +0100 Message-ID: <2025011246-appealing-angler-4f22@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x c9a40292a44e78f71258b8522655bffaf5753bdb # git commit -s git send-email --to '' --in-reply-to '2025011246-appealing-angler-4f22@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From c9a40292a44e78f71258b8522655bffaf5753bdb Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 8 Jan 2025 10:28:05 -0700 Subject: [PATCH] io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period io_eventfd_do_signal() is invoked from an RCU callback, but when dropping the reference to the io_ev_fd, it calls io_eventfd_free() directly if the refcount drops to zero. This isn't correct, as any potential freeing of the io_ev_fd should be deferred another RCU grace period. Just call io_eventfd_put() rather than open-code the dec-and-test and free, which will correctly defer it another RCU grace period. Fixes: 21a091b970cd ("io_uring: signal registered eventfd to process deferred task work") Reported-by: Jann Horn Cc: stable@vger.kernel.org Tested-by: Li Zetao Reviewed-by: Li Zetao Reviewed-by: Prasanna Kumar T S M Signed-off-by: Jens Axboe diff --git a/io_uring/eventfd.c b/io_uring/eventfd.c index fab936d31ba8..100d5da94cb9 100644 --- a/io_uring/eventfd.c +++ b/io_uring/eventfd.c @@ -33,20 +33,18 @@ static void io_eventfd_free(struct rcu_head *rcu) kfree(ev_fd); } +static void io_eventfd_put(struct io_ev_fd *ev_fd) +{ + if (refcount_dec_and_test(&ev_fd->refs)) + call_rcu(&ev_fd->rcu, io_eventfd_free); +} + static void io_eventfd_do_signal(struct rcu_head *rcu) { struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu); eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE); - - if (refcount_dec_and_test(&ev_fd->refs)) - io_eventfd_free(rcu); -} - -static void io_eventfd_put(struct io_ev_fd *ev_fd) -{ - if (refcount_dec_and_test(&ev_fd->refs)) - call_rcu(&ev_fd->rcu, io_eventfd_free); + io_eventfd_put(ev_fd); } static void io_eventfd_release(struct io_ev_fd *ev_fd, bool put_ref)