From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 42EE12DCC0C for ; Wed, 25 Jun 2025 16:42:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750869759; cv=none; b=lw4lrSVQiyBqL2r4u3gCy5EPSaOo92HaUN76OfZ6sYst8g/mM7QWtHXHY12SL8g5zGOLrp0zoGI6o6w2wPX6zY0gVdvXb2QMue2Y75NMLIaJudnX1xIX8Ys4JRPbERwO7J4daUv8azCIyPqJomtJA2fc7tk5L6VvPW+oNit86eA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750869759; c=relaxed/simple; bh=44ko/fmtNx60IUlho7h1UTPgGsvvynhop7gc9hSNZnU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Yzv3UTwdwkze/+JvzrB2kJwAd2tLdfLcYzOsCKo6WClRYQvh2CHFgtj9zpR4YJJssEI6tOuQOAdiBX9RYtLR+scXREvFZVdTX1tF7rwscwCnLDcv+0OY7Spsr+92cDw3/24LInJuu10NF7rCMVcvFaM2bbnaC0+1cLqz8cD1tjs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=EX1XKoIG; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="EX1XKoIG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1750869756; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/a0gvGz5rx3EgvNrbX/tSGjobG6JYUJUrnXePFFIcmM=; b=EX1XKoIGTkTg1nkJEc1DZkQr/o9Ab48j6zgTU5AbycA+6oiZMEhU5+wjke6PPcWTakgQEJ y2IpMKMQFEBvX0TgrKpWepYUI9gVTXXLi+FMhFxhkxepp3JhZViolL2RE1z+ZaD1/+z2Qs i7c0PRTDW0z1DYT2IEp0wBSqF/6hi2o= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-597-F4x2SXjKPgWFtbBaDBnr0g-1; Wed, 25 Jun 2025 12:42:30 -0400 X-MC-Unique: F4x2SXjKPgWFtbBaDBnr0g-1 X-Mimecast-MFC-AGG-ID: F4x2SXjKPgWFtbBaDBnr0g_1750869749 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C705318089B6; Wed, 25 Jun 2025 16:42:28 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.42.28.81]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 2E7DC180035E; Wed, 25 Jun 2025 16:42:24 +0000 (UTC) From: David Howells To: Christian Brauner , Steve French Cc: David Howells , Paulo Alcantara , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Paulo Alcantara Subject: [PATCH v2 01/16] netfs: Fix hang due to missing case in final DIO read result collection Date: Wed, 25 Jun 2025 17:41:56 +0100 Message-ID: <20250625164213.1408754-2-dhowells@redhat.com> In-Reply-To: <20250625164213.1408754-1-dhowells@redhat.com> References: <20250625164213.1408754-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: v9fs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 When doing a DIO read, if the subrequests we issue fail and cause the request PAUSE flag to be set to put a pause on subrequest generation, we may complete collection of the subrequests (possibly discarding them) prior to the ALL_QUEUED flags being set. In such a case, netfs_read_collection() doesn't see ALL_QUEUED being set after netfs_collect_read_results() returns and will just return to the app (the collector can be seen unpausing the generator in the trace log). The subrequest generator can then set ALL_QUEUED and the app thread reaches netfs_wait_for_request(). This causes netfs_collect_in_app() to be called to see if we're done yet, but there's missing case here. netfs_collect_in_app() will see that a thread is active and set inactive to false, but won't see any subrequests in the read stream, and so won't set need_collect to true. The function will then just return 0, indicating that the caller should just sleep until further activity (which won't be forthcoming) occurs. Fix this by making netfs_collect_in_app() check to see if an active thread is complete - i.e. that ALL_QUEUED is set and the subrequests list is empty - and to skip the sleep return path. The collector will then be called which will clear the request IN_PROGRESS flag, allowing the app to progress. Fixes: 2b1424cd131c ("netfs: Fix wait/wake to be consistent about the waitqueue used") Reported-by: Steve French Signed-off-by: David Howells Reviewed-by: Paulo Alcantara cc: linux-cifs@vger.kernel.org cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org --- fs/netfs/misc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c index 43b67a28a8fa..0a54b1203486 100644 --- a/fs/netfs/misc.c +++ b/fs/netfs/misc.c @@ -381,7 +381,7 @@ void netfs_wait_for_in_progress_stream(struct netfs_io_request *rreq, static int netfs_collect_in_app(struct netfs_io_request *rreq, bool (*collector)(struct netfs_io_request *rreq)) { - bool need_collect = false, inactive = true; + bool need_collect = false, inactive = true, done = true; for (int i = 0; i < NR_IO_STREAMS; i++) { struct netfs_io_subrequest *subreq; @@ -400,9 +400,11 @@ static int netfs_collect_in_app(struct netfs_io_request *rreq, need_collect = true; break; } + if (subreq || !test_bit(NETFS_RREQ_ALL_QUEUED, &rreq->flags)) + done = false; } - if (!need_collect && !inactive) + if (!need_collect && !inactive && !done) return 0; /* Sleep */ __set_current_state(TASK_RUNNING);