From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 06182266560; Mon, 1 Sep 2025 11:40:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756726840; cv=none; b=kCqQOSp/bn+5inpKMYrpIX9WgVOYA46LHB4TgBOC01uEIQUMetPQ39Kue5Ia6tdjTVZ+EDwJGcRzvxS3Lhte6MppYoR1DfeHM1b0+5uZKkIoq3QyCyyfafcF4RN6eDCtpdARoPGZQr4H0bGI38M3sR4dRSEa9ThIhBSp1p+705o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756726840; c=relaxed/simple; bh=npXEGBJxOhe9dMOf61TdmnMyKpImRV8CKnQho0op6UI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=LSdg7Zv0DuUFj8z9jsP90i+8DKcZinF8sJSBBFQsRHnh52UoWKzmshtwN8iLpgU5HbBLx9gZuBKefqV5ZnFPH4ZnqCqm1Utjs48rmAGfufQTAeSLzG3kMdujZ5N3kUzLtI7tZUKSn626bL+V/M0pNbVVsLOGK6C3C/aZI+iBR58= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hf913tWs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hf913tWs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6E538C4CEF0; Mon, 1 Sep 2025 11:40:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756726839; bh=npXEGBJxOhe9dMOf61TdmnMyKpImRV8CKnQho0op6UI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=hf913tWs/nE9twl+/PuHiYYLD632B5D3fYbOcnamDPr/ri1OioeiLSWLp1+5rCD4H 6nNALQXfYG2jI4Bxd8enmtCs6l3JziM2HRDvrsE0ueeRh4H/z7HNMKUa44I53Ru0sN jLGkBiVEHxFMBpyYQRuKZMPuXZg2vawGm+ixpCC5EwxlU4unSha4sETT1spu3uXYtY nOyNR4tro1pGQatTGOKKWym1+AUBMWfhIuQNIBgWdBWwdWiF1EXdrVH6qSJ0EAiI2j 7iJHUSWtQDbfDltX3r88RaT98MHjxBdGh6LLncOZpmLHxlYupi4jEHZ7Ah21km6oKW AN/CMlh8u/ZUA== Message-ID: <5664a9dfe03b5ed7ef496a8c03384643023bb63b.camel@kernel.org> Subject: Re: [Question]nfs: never returned delegation From: Jeff Layton To: Li Lingfeng , Trond Myklebust , "zhangjian (CG)" , anna@kernel.org Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Chuck Lever , NeilBrown , yangerkun , "zhangyi (F)" , Hou Tao , "chengzhihao1@huawei.com" , Li Lingfeng Date: Mon, 01 Sep 2025 07:40:37 -0400 In-Reply-To: References: Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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2025/8/11 21:03, Trond Myklebust =E5=86=99=E9=81=93: > > On Mon, 2025-08-11 at 20:48 +0800, zhangjian (CG) wrote: > > > Recently, we meet a NFS problem in 5.10. There are so many > > > test_state_id request after a non-privilaged request in tcpdump > > > result. There are 40w+ delegations in client (I read the delegation > > > list from /proc/kcore). > > > Firstly, I think state manager cost a lot in > > > nfs_server_reap_expired_delegations. But I see they are all in > > > NFS_DELEGATION_REVOKED state except 6 in NFS_DELEGATION_REFERENCED (I > > > read this from /proc/kcore too). > > > I analyze NFS code and find if NFSPROC4_CLNT_DELEGRETURN procedure > > > meet ETIMEOUT, delegation will be marked as NFS4ERR_DELEG_REVOKED and > > > never return it again. NFS server will keep the revoked delegation in > > > clp->cl_revoked forever. This will result in following sequence > > > response with RECALLABLE_STATE_REVOKED flag. Client will send > > > test_state_id request for all non-revoked delegation. > > > This can only be solved by restarting NFS server. > > > I think ETIMEOUT in NFSPROC4_CLNT_DELEGRETURN procedure may be not > > > the only case that cause lots of non-terminable test_state_id > > > requests after any non-privilaged request. > > > Wish NFS experts give some advices on this problem. > > >=20 > > You have the following options: > >=20 > > 1. Don't ever use "soft" or "softerr" on the NFS client. > > 2. Reboot your server every now and again. > > 3. Change the server code to not bother caching revoked state. Doin= g > > so is rather pointless, since there is nothing a client can do > > differently when presented with NFS4ERR_DELEG_REVOKED vs. > > NFS4ERR_BAD_STATEID. > > 4. Change the server code to garbage collect revoked stateids after > > a while. > >=20 > I found that a server-side bug could also cause such behavior, and I've > reproduced the issue based on the master (commit b320789d6883). > nfs4_laundromat=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0nfsd4_delegreturn I think you may be right about the race. The details are a little off though. The important bit here is that the laundromat also calls this unhash_delegation_locked before doing the list_add/del. > =C2=A0list_add // add dp to reaplist > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 // by dl_recall_lru > =C2=A0list_del_init // delete dp from > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0// reaplist > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0destro= y_delegation > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 unhas= h_delegation_locked ...which _should_ make the above unhash_delegation_locked return false, so that list_del_init never happens. > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0list_del_init > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0// dp was not added to any list > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0// via dl_recall_lru > =C2=A0revoke_delegation > =C2=A0list_add // add dp to cl_revoked > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 // by dl_recall_lru >=20 > The delegation will be left in cl_revoked. >=20 > I agree with Trond's suggestion to change the server code to fix it. >=20 >=20 ...but there is at least one variation on what you wrote above where it could get stuck back on the cl_revoked list after the delegreturn. The delegreturn does set the SC_STATUS_CLOSED bit on the stateid, so something like this (untested) patch, perhaps? ------------8<---------- diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index d2d5e8e397a4..e594ded49e60 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1506,7 +1506,7 @@ static void revoke_delegation(struct nfs4_delegation = *dp) trace_nfsd_stid_revoke(&dp->dl_stid); =20 spin_lock(&clp->cl_lock); - if (dp->dl_stid.sc_status & SC_STATUS_FREED) { + if (dp->dl_stid.sc_status & (SC_STATUS_FREED | SC_STATUS_CLOSED)) { list_del_init(&dp->dl_recall_lru); goto out; } --=20 Jeff Layton