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=1793934671; b=xZ+aJz44X1US4otdv5AR9jE61aTjNVGlCrB7dm3KoA2GjYgkkK1MCYDwkQrhJ7y6ZxR9 fzT3bUClrg9aDgIy6HbOM6ADNdQQXiRASY6VttNQJpEVRcmTPRABxJpwgOsFVc9aHczwE EcYcBXxMV6uHu7kyl8/8e61AoWUGiK9/48H+Pa36fTskoiyb4XWPX4vQhyDKabbYGcNUx z1irjez2ubywlaO86/Gm+4gQV431AMjf+Pcjq8pnngmIBOcJNKMR6+ASGddBG3M4WgIJc WT7XrizUNOoHqSIyWz+KKRIut5ZF6aIW31NR99+yGvR8NPUOxnIRAD88O6K0ksbdHfA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793934671; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=T3lIOpr/GCoIrygqMrURvcdk8UIYby13eFOnpOMxq4Q=; b=MtrMffRwu4zzcjuMrcVhL4rayvh/Yoti4i6hCn9W/S0I0NFK1sRB/u3XHq/itEGwFWEM 1SpXvzMo3qWSxOpH4s2J+foVYdJY4Ix/lCMzDvZcrRn+9KyiAPB3clS5eYcVEGxWTs84s /bNQb81Y2zzVRqyA/P+T79RhSdo8NLUVPbGFd1xq3GZmh5lBPOZPuZqXfx6uo0myx3D0K yYK6dzOUlu8M4z+8WFNBux4PaTM5P9hDQeM/GUVN0ylCLRQXtl3G9xvlVcvsYtdc3+xVH nhvtusyc6yv+P9wxbRYYnoL874Gnk6Fpm0w29c16hum9nQyN2xRLZ+OgGk7bZ7O1Z1A== 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=dPmu0qaf; 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 90A58606A329 for ; Fri, 6 Nov 2026 03:11:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=dPmu0qaf Received: by smtp.kernel.org (Postfix) with ESMTPSA id C94541F008A2; Fri, 6 Nov 2026 03:11:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793934671; bh=T3lIOpr/GCoIrygqMrURvcdk8UIYby13eFOnpOMxq4Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dPmu0qafeBf39uoDgPbkvvvU3D/ChG3NvSliGQJpewLy1r+uLoRLlT1zqvVTRY4SS u6eMVouDpodgC+9akEIGcYBnVZCoKLs4aOrcrzFOniIDmlVVqnbYRa5z5cx7miEjJj BcyD6b2XfUQPDKRcoM2LmJn08b/krYavVfxZPbewn7qWueaTbDwOSxk2v/W68jZUId ssgAPvphQrdiTyJ/5nrOmJI89NIijLmSN9ya0Wqd1+8zsoIqqtdKn9YRLulL+GdLCO JKEAkdpNZma3ADXE34Vx2y0AcL+UaUMbCeSjwRWCeVa2cnrX2obI4uEk0pgIuIvZEX 0Fe+4rrOo6O8A== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , syzbot+edbebd898142ee5e24ce@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH 6.6.y 2/2] NFSD: Complete a cld upcall when the daemon closes the pipe Date: Thu, 5 Nov 2026 22:11:08 -0500 Message-ID: <20261106031101.3999663-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261106031101.3999663-1-sashal@kernel.org> References: <2026110454-freefall-tapioca-21ff@gregkh> <20261106031101.3999663-1-sashal@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-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit 2a83fcb50f3c25c493cc4389619340fefe9d6ac4 ] Once nfsdcld has read a whole upcall, rpc_pipe_read() unlinks the message from every pipe list, so the purges in rpc_pipe_release() and rpc_close_pipes() no longer reach it. cld_upcall_ops supplies no .release_pipe callback, and cld_pipe_destroy_msg() returns without completing the upcall because a downcall is expected to follow. A daemon that exits between the read and the write therefore strands its waiter: the nfsd thread sleeps in TASK_UNINTERRUPTIBLE in __cld_pipe_upcall() and never returns, hung task warnings follow, and the server cannot be shut down. Add a .release_pipe that completes every upcall the daemon has consumed. cu_inflight distinguishes those from upcalls still queued on the pipe, which the framework purges before it calls this callback; cld_pipe_downcall() removes an upcall it accepts from cn_list under the same lock. Neither can be completed twice. Fail the stranded upcall with -EPIPE rather than the -EAGAIN that makes cld_pipe_upcall() retry. The daemon consumed the request, so whether it acted on it before exiting is unknown. Fixes: f3f8014862d8 ("nfsd: add the infrastructure to handle the cld upcall") Reported-by: syzbot+edbebd898142ee5e24ce@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-nfs/6a99f6f0.2e567484.299ffc.000c.GAE@google.com/ Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260901-alemi-v2-7-e163f94a3a6e@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4recover.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index 2c75871f3c479..89441b5cb0603 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -943,10 +943,34 @@ cld_pipe_destroy_msg(struct rpc_pipe_msg *msg) complete(&cup->cu_done); } +/* + * An upcall the daemon has consumed is off every pipe list, so the + * purge in rpc_pipe_release() and rpc_close_pipes() cannot reach it. + * Release its waiter here instead; no downcall can arrive now. + */ +static void +cld_release_pipe(struct inode *inode) +{ + struct nfsd_net *nn = net_generic(inode->i_sb->s_fs_info, nfsd_net_id); + struct cld_net *cn = nn->cld_net; + struct cld_upcall *cup; + + spin_lock(&cn->cn_lock); + list_for_each_entry(cup, &cn->cn_list, cu_list) { + if (!cup->cu_inflight) + continue; + cup->cu_inflight = false; + cup->cu_pipe_msg.errno = -EPIPE; + complete(&cup->cu_done); + } + spin_unlock(&cn->cn_lock); +} + static const struct rpc_pipe_ops cld_upcall_ops = { .upcall = rpc_pipe_generic_upcall, .downcall = cld_pipe_downcall, .destroy_msg = cld_pipe_destroy_msg, + .release_pipe = cld_release_pipe, }; static struct dentry * -- 2.53.0