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=1794046329; b=1VhWiYZwFJkne0fyTRFkkqLs7GdbTLupDj/hMvSKUpS8fGWufrlHmd+MZl4pcIcLJDlQ R55RNU8Qnps3Czo7GubNxUbT6cFeynGjk5fBIduG2qeFfdDDjzdT9kzjL0TrcOhG2EOnb 3RTfcMN0WzpBLVShyt37BeWwb1HaXwhOob/R7KAGYp3Lut+RMx+62hQinnX1Jh/6c0DTZ oM11bStiIMKQkZxW6fiKZ5LnF0lY6i4uguxvZRJmEI0Jg+ZLsxzR0fzLg53dMxGlquAkH gEFyiEnYB2+zNAm/QEgQZ+OjFkKb45c2Ecdcs6ZYucOTfMYvqgKbf41Woa1CbNF36Sg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794046329; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=5Nnr7/MJHCfX3DhKqlYgQEvVQhIKg3KcsyWjJeWd5YY=; b=zQGqbY0loLqpEBSlus3Rjjz7yXlrBmrI7Op43E2JvujF6XrzAd9ynxGOPyXQqTlPrwIW EWxi8lWCmAQxYZpQQDZz2Alw2OcJVW9QXyV/FQtlRYINUT0Smh+J69Kdxh6FqKVkuaa6G G86X+wXO2eYfSzlHIyQwNvRkBEqlSOh0BmsDkm1waa95hOLsydVy5qqddxsAYgExQnLI1 myfFnNu42qEeeLQ8gA6wlmbsz7jtwPIY2Sm6TPOe0qZ3N+kABRYlFJbu9tsv47X65uOTG tIhYGcFDk64VsibwsCvFK30kGKRKW/X+Vx8km5LO0vbSBncLRj8v5lBTgMRBJqdXf8A== 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=Tc8dx4Ut; 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 50733606A326 for ; Sat, 7 Nov 2026 10:12:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Tc8dx4Ut Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB4A71F008A1; Sat, 7 Nov 2026 10:12:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794046329; bh=5Nnr7/MJHCfX3DhKqlYgQEvVQhIKg3KcsyWjJeWd5YY=; h=From:To:Cc:Subject:Date; b=Tc8dx4Ut1Ue+202C5hBu6Pf4E8XR91bKd1L6ZN6QsTiPRyZPD1GfZQDyKxwA2CKZu TTpXaqlNDiQylihYshNRP7DzfhGLqoebz10X0rwXJ660qICsbu4CK7S6TGrg+O5VSc LERaQUumRoonH+KFtTQMWEsPMHY//iDsBhTOqOqJbEZwi1ZMmObMtb4tJCsVTfQOvC Plv9ewShh6NkmZglYjHcJLnlIHFs5sTeiuMITq3GyboFpPrgA7tpu/H1nfXvlfAAPg I1orHKVHamt3GetyhpNmizz2QKaa6Xn3s9tClT7r/07K1s0AJUqDlRL0cZf8BS+Orq Y2nzG3Y0n38vA== From: Sasha Levin To: tom.leiming@gmail.com, josef@toxicpanda.com, axboe@kernel.dk Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] ublk: mark the io command cancelable before publishing it" failed to apply to 6.18-stable tree Date: Sat, 7 Nov 2026 05:12:07 -0500 Message-ID: <20261107051207-failed-6.18-a261f0cacacc@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@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=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x a261f0cacacc022e4fab5b8e38c59f74ce4942e8 # git commit -s git send-email --to '' --in-reply-to '20261107051207-failed-6.18-a261f0cacacc@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From a261f0cacacc022e4fab5b8e38c59f74ce4942e8 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sun, 11 Oct 2026 01:35:45 -0500 Subject: [PATCH] ublk: mark the io command cancelable before publishing it MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit FETCH, COMMIT_AND_FETCH and NEED_GET_DATA publish the command in io->cmd before marking it cancelable. A cancel from the control path (STOP_DEV, QUIESCE_DEV) can complete it in between: issue path control-path cancel io->cmd = C take C, io_uring_cmd_done(C): C not marked, nothing to unlink ublk_prep_cancel(C) the completed C is linked on the cancelable list ring exit: the cancel walk hits it → GPF (KASAN, with a delay added) Mark the command before ublk_fill_io_cmd() publishes it. The handlers run with uring_lock held, as io_uring's cancel walk does, so marking takes no lock and the walk can't see a marked command before it is published. smp_wmb() orders the mark before the io->cmd store; the cancel loads cmd with READ_ONCE(io->cmd) before reading cmd->flags. A marked command has to be completed by io_uring_cmd_done(), so a failed FETCH and the inline UBLK_IO_RES_OK of NEED_GET_DATA now do that. The CQE is the same. Fixes: 216c8f5ef0f2 ("ublk: replace monitor with cancelable uring_cmd") Cc: stable@vger.kernel.org Tested-by: Josef Bacik Signed-off-by: Ming Lei Link: https://patch.msgid.link/20261011063555.1142277-3-tom.leiming@gmail.com Signed-off-by: Jens Axboe --- drivers/block/ublk_drv.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 125f45ce0392f..c105826a095bb 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -2800,7 +2800,8 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, u16 tag, done = !!(io->flags & UBLK_IO_FLAG_CANCELED); if (!done) { io->flags |= UBLK_IO_FLAG_CANCELED; - cmd = io->cmd; + /* dependency ordered against smp_wmb() in ublk_prep_cancel() */ + cmd = READ_ONCE(io->cmd); io->cmd = NULL; } spin_unlock(&ubq->cancel_lock); @@ -3162,6 +3163,12 @@ ublk_fill_io_cmd(struct ublk_io *io, struct io_uring_cmd *cmd) return req; } +/* + * Call before ublk_fill_io_cmd() publishes @cmd in io->cmd: a control-path + * cancel may complete any command found there, and io_uring_cmd_done() only + * takes it off the cancelable list if it is marked already. The handlers + * hold uring_lock, so marking takes no lock. + */ static inline void ublk_prep_cancel(struct io_uring_cmd *cmd, unsigned int issue_flags, struct ublk_queue *ubq, u16 tag) @@ -3175,6 +3182,8 @@ static inline void ublk_prep_cancel(struct io_uring_cmd *cmd, pdu->ubq = ubq; pdu->tag = tag; io_uring_cmd_mark_cancelable(cmd, issue_flags); + /* pairs with the cancel loading cmd from io->cmd, then cmd->flags */ + smp_wmb(); } static void ublk_io_release(void *priv) @@ -3422,11 +3431,11 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd, ret = ublk_check_fetch_buf(ub, addr); if (ret) goto out; + /* before ublk_fetch() publishes io->cmd, see ublk_prep_cancel() */ + ublk_prep_cancel(cmd, issue_flags, ubq, tag); ret = ublk_fetch(cmd, ub, io, addr, q_id); if (ret) - goto out; - - ublk_prep_cancel(cmd, issue_flags, ubq, tag); + goto out_done; return -EIOCBQUEUED; } @@ -3470,6 +3479,7 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd, if (ret) goto out; io->res = result; + ublk_prep_cancel(cmd, issue_flags, ubq, tag); req = ublk_fill_io_cmd(io, cmd); ublk_apply_io_buf(ub, io, cmd, addr, &auto_buf, &buf_idx); if (buf_idx != UBLK_INVALID_BUF_IDX) @@ -3488,19 +3498,24 @@ static int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd, * uring_cmd active first and prepare for handling new requeued * request */ + ublk_prep_cancel(cmd, issue_flags, ubq, tag); req = ublk_fill_io_cmd(io, cmd); io->buf.addr = addr; if (likely(ublk_get_data(ubq, io, req))) { __ublk_prep_compl_io_cmd(io, req); - return UBLK_IO_RES_OK; + ret = UBLK_IO_RES_OK; + goto out_done; } break; default: goto out; } - ublk_prep_cancel(cmd, issue_flags, ubq, tag); return -EIOCBQUEUED; + out_done: + /* marked cancelable: complete through io_uring_cmd_done() */ + io_uring_cmd_done(cmd, ret, issue_flags); + return -EIOCBQUEUED; out: pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n", __func__, cmd_op, tag, ret, io ? io->flags : 0); -- 2.53.0