From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 968093CF022; Sun, 11 Oct 2026 12:07:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791720464; cv=none; b=Vjs+aTWr/TzvFSCQc+yaku9feYiV+qOlc0Swf6C9Unq9Bi9w1lmzlyVI+/tyD4xfhM84scveSeCXDapedrIMS7qlaseoOxaTrKcGPlyTy6SLku2ZQhyWfUzl6RNDIBZlVle/Gyu7L6bYcNIlchFhd+cZ4siDuaJ9xQfbssl5NDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791720464; c=relaxed/simple; bh=7N2q9l5nBXyZzPAwAnlgHaJXYTaIxTpsZkpSTN5koro=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=FkwGhx3rBVc2aq1M3j9pHK8Ngilh9ib8rYNMmsyVwpkh/5RCrl0KnN6XsQWtO1Bm+IaHMynKc4MljfunxnVklXdqjuV0eI/Wm8lCA/Cr3ceaRjvViyb30gBluX4BdCKinmNen09+pQ9srNLiPfqk7Ry4wdmTW4JQ9CBnyNVJRfU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Wy3JL97O; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Wy3JL97O" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B60C1F0089B; Sun, 11 Oct 2026 12:07:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791720459; bh=1/BM11TaH1DkAq8nCc5GVlPtgZDkWqiFYSD/goVwjiI=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=Wy3JL97OVL1UrMF5h243ciRiSvtZzn3Kfy7DPC0jPU3sgCSjJDA1zio3xOlx2gmDb WMQvLH9jhis3283wxN5wkxbbK/EcOArvIsu+GfHJ9v5P9uSeAlzaBTWXrQW+Ktdpyo kdUpNZjQ8TRhISq33VOUk2PPv1EqfDQOPNVdZoy8CQT2QNn7nombG2VtmTW+Clif5M s2CKowx8xn0vZ04u2p43d/noAn3vIMfRh/e77dhK7KsZsI3kfxYZK3R7g5t3MLVW2R oaBnXRH4AOjDvAZHdIWW4zv+qLEcJU98++gAElxvv5kE6k+8QGpsaSyvytYTPnQaB0 as1sg0/3JdzPQ== Message-ID: <1eca2a80d8e90375682adeadcaf8b007ae2cc720.camel@kernel.org> Subject: Re: [REGRESSION] 7.2.4: nfsd sends CB_OFFLOAD with all-zero stateid, async NFSv4.2 COPY never completes From: Jeff Layton To: Greg KH , Lubos Rendek Cc: stable@vger.kernel.org, regressions@lists.linux.dev, Chuck Lever , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Sun, 11 Oct 2026 08:07:36 -0400 In-Reply-To: <2026101121-staining-scheme-358a@gregkh> References: <7cc824c4-632d-49df-ae5e-cfcbb5bf76ad@proxmox.com> <2026101121-staining-scheme-358a@gregkh> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Sun, 2026-10-11 at 09:19 +0200, Greg KH wrote: > On Sun, Oct 11, 2026 at 06:30:40AM +1100, Lubos Rendek wrote: > > Since 7.2.4, an NFSv4.2 server-side COPY between two exports of a Linux > > NFS server never completes, because nfsd sends CB_OFFLOAD with an > > all-zero stateid. >=20 > Can you just use git bisect to determine the offending commit? >=20 > And is this also the same for 7.3-rc? >=20 >=20 I took a look: I believe this is a bug in 14b978e8d05c ("nfsd: fix stale s2s_cp_stateids IDR entry for async COPY"), which is d0beaee498e1 in mainline. In v7.3, this bug gets fixed by f307b4f7ed17 ("nfsd: split nfsd4_copy into transient and durable async copy objects"), which was part of the refactor of the async COPY code. We should probably just take Lubos' two-line fix as a separate one-off patch for stable. Backporting the COPY code refactor is too risky IMO. Clanker analysis follows if you're interested. I think it's largely correct: -----------------8<----------------------- =E2=97=86 Diagnosis confirmed: the report is correct, and this is a stable-= only regression from an incomplete backport. Root cause is the order of dup_copy_fields() vs nfs4_init_copy_state() in= nfsd4_copy(): =E2=80=A2 result points at the transient &u->copy.cp_res. =E2=80=A2 dup_copy_fields() copies cp_res (including cb_stateid) from tra= nsient to async_copy. =E2=80=A2 nfsd4_send_cb_offload() builds CB_OFFLOAD from async_copy->cp_r= es. Pre-d0beaee498e1, mainline did init =E2=86=92 write result->cb_stateid = =E2=86=92 dup_copy_fields(), so both the COPY reply and async_copy->cp_res.cb_stateid got the stateid. But the s2s= _cp_stateids IDR stored a pointer to &u->copy.cp_stateid, which is transient COMPOUND buffer memory= . d0beaee498e1 ("nfsd: fix stale s2s_cp_stateids IDR entry for async COPY",= stable 14b978e8d05c) fixed the IDR lifetime by doing dup_copy_fields() first, then nfs4_init_copy_state(nn, async_copy), then writing only result->cb_statei= d. That leaves async_copy->cp_res.cb_stateid zero, because the dup already happened. Res= ult: COPY reply has a valid stateid, CB_OFFLOAD has all-zero, client can't match it in nfs42_pr= oc_copy and hangs. This matches your packet table exactly. Mainline is fixed by f307b4f7ed17 ("nfsd: split nfsd4_copy into transient= and durable async copy objects"), which moves the durable stateid out of the duplicated struct s= o it can safely do init =E2=86=92 write cb_stateid =E2=86=92 dup again. Current code in fs/nfsd/nfs4proc.c:= 2242 has the explicit comment "dup after writing cb_stateid; duplicating first would leave the callback= stateid zeroed." I verified the callback path in fs/nfsd/nfs4proc.c:2104 copies from cp_copy= .cp_res, and dup_copy_fields in fs/nfsd/nfs4proc.c:2051 copies cp_res. Your minimal stable fix is the right shape for stable. A plain reorder wo= n't work on the old layout because dup_copy_fields() also copies cp_stateid, so init-then-dup= would clobber async_copy->cp_stateid with the transient's zero value. Copying the new s= tateid into both result->cb_stateid and async_copy->cp_res.cb_stateid after init preserves= the IDR fix and fixes the callback. The alternative is backporting the full restructuring serie= s (f307b4f7ed17, 80c376183411, etc.), which is heavier for stable. #regzbot introduced: v7.2.3..v7.2.4 looks correct. The 6.12 sync-copy obs= ervation is expected: that branch largely forces COPY synchronous, so it doesn't reach the asyn= c/CB_OFFLOAD path. I did not run the reproducer or inspect a 7.2.y tree locally; verificatio= n was by reading mainline and the d0beaee498e1 before/after versions in this checkout. --=20 Jeff Layton