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=1794063079; b=YIek8DdJv1V62nWP+2Kb/f7pxZMEWBajbV8kt3n9PzdbzrVTX2lmowKdgGCQa7DZI1Sd COgd4oAckOWgO07K1djfa/jvr0ADOUCmvlkuP45MI/dSqOOhubh9edAfSRW9EjWV19UdF BWZDBO/7jWl3jWCJnIdDL4ZdpcKdBKFVc2ZdGQwhs1g3/oFUYzRL/UtPkGKmXOVFJbNDj ruC6L5oMYWKqblWhEHLB/tv8xUnn3y73bTjHGAxjcMwLfUauDIyV4M1NZ14Szm+U32VkE h9L/jk5jnp8tdt1B/S0sBAYgYnAwYyG2XY3dqVaD8y7G7UM7w65OVYo8EMtPrGA7Gpg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794063079; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=2ZG/lulIn0qlE6Rcd6tdHrHA/3qbLaH/x5+RK67jcM0=; b=ON+gOwoXs/wzOTSFTHbKBXJXQhSqWobqnRYRsmiJ18EtKrURdmayo6M2qo0xjBwc8sPU stvUG6oM1IU0+0tR1Mo4MkqnPghWamPkca8bHa9CRvKYRyH8ERuEUiQnKhk5vnEvC4PPf +PSCpdITYTxtszoGpDhVcLORiy5aFJ1r4ZLiFVWKgMr3cGRy6JOU1vLffgXSi79+934CI uOuf1MSvW/Ku+0BofRiXJvF0OvadlHKPYkNvC6mVo6xo8z0Y3HHyALE50TBReHNL12hhe FMxuYq/tItorX1haAs09ksFf9ey0TuAD5IinI6G4JTIG1MBMf7dW7abGPj+O07OPhxQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=C5VXkS8Y; 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 014CD606D802; Sat, 7 Nov 2026 14:51:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=C5VXkS8Y Received: by smtp.kernel.org (Postfix) with ESMTPSA id A21991F0089F; Sat, 7 Nov 2026 14:51:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794063078; bh=2ZG/lulIn0qlE6Rcd6tdHrHA/3qbLaH/x5+RK67jcM0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=C5VXkS8YcREh96BaPpD/cy97FGEXHhbeaYxRzAQ+snP+Alj5JZzA+b6H9ed9Ep4Mq Jb3iKT1IOeE+QMYj+bfedKXXmM9yNc2fXRxX2hf84q95sN07y6iXs7E6/LjqwKHgWQ 2+TfeXWkwLfW6jibXFIS8RI7VtCz4YlumBsfzONg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mikulas Patocka , Sasha Levin Subject: [PATCH 6.18 319/869] dm-writecache: fix uncommitted_blocks underflow Date: Sat, 7 Nov 2026 08:50:01 -0500 Message-ID: <20261107134903.295587496@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134852.069646174@linuxfoundation.org> References: <20261107134852.069646174@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore 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-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka [ Upstream commit 8a0cc5f3446a324b13f62020eeddb32d6ba1c2db ] Revert the commit 39495b12ef1cf602e6abd350dce2ef4199906531 writecache_bio_copy_ssd sets wc->uncommitted_blocks = 0; and then queues the flush work: queue_work(wc->writeback_wq, &wc->flush_work); It may be possible that discard is dispatched in this window, and the discard would decrement wc->uncommitted_blocks to -1U. Note that this bug is benign - wc->uncommitted_blocks is only used to trigged autocommit, so decrementing it to -1U will trigger a spurious autocommit, but won't cause any data corruption. Signed-off-by: Mikulas Patocka Assisted-by: Claude:claude-opus-5 Fixes: 39495b12ef1c ("dm writecache: correct uncommitted_block when discarding uncommitted entry") Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin --- drivers/md/dm-writecache.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index d3f93a871a142..63e18c6f1325f 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -899,8 +899,6 @@ static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_ } discarded_something = true; } - if (!writecache_entry_is_committed(wc, e)) - wc->uncommitted_blocks--; writecache_free_entry(wc, e); } -- 2.53.0