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=1794361670; b=2qbjn4dHhJKcfDCtzsPf7NMz1RKh6QZkfLgnDlvHwrGzif/A4+ranhH3dgxtc93G9Xl5 BwFGWLoQwA2yx0lUjRm56oJMXXl8u3QK4XepDtGLYtnNKt4inKQEnBfovG2YNeBO4tzgj EQ5MjJbn0iXacDXPKG/0Uwp/qjGstS7E1vzWJH9w+p5yyYSBaHcw4+YNcoHQC8GlW8/C7 hXE2/bN09CjQ+qCo3XEEniitbGmXyNSDk74fzJqc/opuhkY6bGPrFxv61lYV1CCrG9Jbd v1r5i7XNGzn2FCgYleKxCExCdztZfX2pcpriY9KTrHC574lfZ3bPcnMJo2xpDsOiF1A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794361670; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Type: Content-Transfer-Encoding; bh=my1r9kVMJeb4mL18Fc9HCqSCZER5bSbizT9L0b9wLJc=; b=V1In0vl8hnKC7KB5f8PPTGbzpCOd5iKzvBph7uP6EX5gFqc+DPDfYKY9Tp6dRlT+I+jP S9XP8x8k6KECEuXs+wpWibOMKg6XP1jXX5ApGlQQeXu9trLjwaiCogvxDpG+GxaRGE1QB ZweoAYFKhmrWQvZ8i0b9IiW4x/ntdz0KPs72z4JFWEeN41Y295/43/ccSZogzrNjvuC8/ FTS5pyr9JNm+2P4H4yatJqCrWo5gWQnYLcbqZh5TD03Jt8k60AsOFydWW3SjjwKT9sT87 BGzl8rh4fIXfyUG37tUVOHWR2cRS1XFVgn935cGPyct/+ryv6ADn4SsDYgyyd62QRuA== 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=Bnr45jHg; 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 47847606A320 for ; Wed, 11 Nov 2026 01:47:50 +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=Bnr45jHg Received: by smtp.kernel.org (Postfix) with ESMTPSA id 57F961F0089F; Wed, 11 Nov 2026 01:47:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794361669; bh=my1r9kVMJeb4mL18Fc9HCqSCZER5bSbizT9L0b9wLJc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Bnr45jHgHYKjv1dkKY8keP/Fnki9vIp8nF4ZRMRaxCkoak5epyW2f7R5PwADiGZ+H WjzYga3Gyovj2bupbHTKoE0dwMU6srheXkWT/RGoj5qjz5c31EnPWjjbF/WoYY9IU9 PnqQJhl4UUGNjaBAGrtR4Svx3t9UqKtez526pui6xCZh0mO1yW0K5Whkoqdw5WXIpD JA2lkPkD1ZjmcOvJ8mkPkOL6QB+0WygfpWC3nkVAAwtoNiRG+bkF9CKL1K73vM8Cpo 4WuFxHdlTBihS56HzCKZQrLYExzXS38SsHQyAzwbxCgjLJiCdUO+uUys7FfQL0efh5 +DFybujKC+Fmg== From: Sasha Levin To: stable@vger.kernel.org Cc: Ming Lei , Josef Bacik , Jens Axboe , Sasha Levin Subject: [PATCH 6.18.y] ublk: mark the io command cancelable before publishing it Date: Tue, 10 Nov 2026 20:47:48 -0500 Message-ID: <20261111014722.402629-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107051207-failed-6.18-a261f0cacacc@kernel.org> References: <20261107051207-failed-6.18-a261f0cacacc@kernel.org> 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 From: Ming Lei [ Upstream commit a261f0cacacc022e4fab5b8e38c59f74ce4942e8 ] 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 [ sashal: passed READ_ONCE(io->cmd) directly to io_uring_cmd_done() instead of storing it in a local variable ] Signed-off-by: Sasha Levin --- drivers/block/ublk_drv.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 6b2035c46daa3..70493dfdda41f 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1993,8 +1993,10 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, unsigned tag, io->flags |= UBLK_IO_FLAG_CANCELED; spin_unlock(&ubq->cancel_lock); + /* dependency ordered against smp_wmb() in ublk_prep_cancel() */ if (!done) - io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, issue_flags); + io_uring_cmd_done(READ_ONCE(io->cmd), UBLK_IO_RES_ABORT, + issue_flags); } /* @@ -2258,6 +2260,12 @@ 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, unsigned int tag) @@ -2271,6 +2279,8 @@ 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) @@ -2511,11 +2521,11 @@ 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, ubq, io, addr); if (ret) - goto out; - - ublk_prep_cancel(cmd, issue_flags, ubq, tag); + goto out_done; return -EIOCBQUEUED; } @@ -2559,6 +2569,7 @@ 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) @@ -2578,19 +2589,24 @@ 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