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 C6E7750276 for ; Wed, 21 May 2025 19:35:44 +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=1747856144; cv=none; b=PT605v6ZcFC+UH55ULC/FSSHxlPKxeqLuCFpQCog3JKRwEjbVM1EcEeBKTq6CsLyN3cVBj8JzEPwfZc2uRcESBl3DdWr3u6GT66QFZQ5mIjpdyVC7rDpps0b/hm42Qv2hYfcbqbM0oHArCjAkUHYg2Yt3Xfuf4gqrIyV/Fhy4mY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747856144; c=relaxed/simple; bh=EaLquBH5djocTnegnlDklz7NyY61VLf4L4go2R+Srho=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=X+14D4PtbibY4UmgkB2Kmvr6O9F4xGIXJ5fiH4MWU2YBMB+5PbYHCg2FLr4u0/nbB1EsjAE5I2+6Ffyu1LqOqa+OWvfe/5wxN1Zp3UFC65wN1Dne9fTtTPNQIIB3kfwLAc9NGIsD+uxFhIbOSZLbNvZfufUKr1tr/BOg7UIXTTg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EjomRSJC; 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="EjomRSJC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0236CC4CEE4; Wed, 21 May 2025 19:35:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747856144; bh=EaLquBH5djocTnegnlDklz7NyY61VLf4L4go2R+Srho=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=EjomRSJCfc/Uk1GDY7RpKLPHnCOuHp3/5xytGc7ZSGdPnDxnHsDMNowsoh8Gdk+Lc 3GdHgG02uZOD0Dm0hy3+AbaCnn8c+1B8lCies+2FmRRYy3s8OtN0oiJzSSz3JpmlIQ sRKcZ7MUJxBMm7vJQ7x0H7QrsTNXcg8w43rQfKoAW97M+3IVpjGMNHnGeq0UmTm3kO sajE6FJa8L6IKmEWdO4cbZiPt7ZdXGBRckMgRx8lb8MKIMzm3+7UTu4Jo/VyH23de/ vGYQjTKx+2Qt5v4FCW0/UBGghaNTn6knCq1u2pViwXPfPd854oMBGjxIuYkUCdTAu2 SSeiTiGhWilxQ== Message-ID: Subject: Re: [PATCH] NFS: Fixes for nfs4_proc_mkdir() error handling From: Jeff Layton To: Anna Schumaker , linux-nfs@vger.kernel.org, trond.myklebust@hammerspace.com Cc: NeilBrown Date: Wed, 21 May 2025 15:35:42 -0400 In-Reply-To: <20250516150010.61641-1-anna@kernel.org> References: <20250516150010.61641-1-anna@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV 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is a valid Linux error code. It does not take into account NFS > error codes, which are well out of the range of MAX_ERRNO. So if > _nfs4_proc_mkdir() returns -NFS4ERR_DELAY (which xfstests generic/477 was > able to consistently hit while running against a Hammerspace server), > PTR_ERR_OR_ZERO() will happily say "no, that's not an error", so we > propagate it up to the VFS who then tries to dput() it. >=20 > Naturally, the kernel doesn't like this: >=20 > [ 247.669307] BUG: unable to handle page fault for address: ffffffffffff= d968 > [ 247.690824] RIP: 0010:lockref_put_return+0x67/0x130 > [ 247.719037] Call Trace: > [ 247.719446] > [ 247.719806] ? __pfx_lockref_put_return+0x10/0x10 > [ 247.720538] ? _raw_spin_unlock+0x15/0x30 > [ 247.721173] ? dput+0x179/0x490 > [ 247.721682] ? vfs_mkdir+0x475/0x780 > [ 247.722259] dput+0x30/0x490 > [ 247.722730] do_mkdirat+0x158/0x310 > [ 247.723292] ? __pfx_do_mkdirat+0x10/0x10 > [ 247.723928] __x64_sys_mkdir+0xd3/0x160 > [ 247.724531] do_syscall_64+0x4b/0x120 > [ 247.725131] entry_SYSCALL_64_after_hwframe+0x76/0x7e > [ 247.725914] RIP: 0033:0x7fe0e22f3ddb >=20 > While I was in the area, I noticed that we're discarding any errors left > unhandled by nfs4_handle_exception(). This patch fixes both of these > issues. >=20 > Fixes: 8376583b84a1 ("nfs: change mkdir inode_operation to return alterna= te dentry if needed.") > Signed-off-by: Anna Schumaker > --- > fs/nfs/nfs4proc.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) >=20 > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > index c7e068b563ff..306dade146e6 100644 > --- a/fs/nfs/nfs4proc.c > +++ b/fs/nfs/nfs4proc.c > @@ -5274,13 +5274,17 @@ static struct dentry *nfs4_proc_mkdir(struct inod= e *dir, struct dentry *dentry, > sattr->ia_mode &=3D ~current_umask(); > do { > alias =3D _nfs4_proc_mkdir(dir, dentry, sattr, label); > - err =3D PTR_ERR_OR_ZERO(alias); > + err =3D PTR_ERR(alias); > + if (err > 0) > + err =3D 0; > trace_nfs4_mkdir(dir, &dentry->d_name, err); > err =3D nfs4_handle_exception(NFS_SERVER(dir), err, > &exception); > } while (exception.retry); > nfs4_label_release_security(label); > =20 > + if (err !=3D 0) > + return ERR_PTR(err); > return alias; > } > =20 (cc'ing Neil) This bug is rather nasty. It would be _really_ nice to have it fixed before v6.15 ships. Could we get confirmation of that? Thanks, --=20 Jeff Layton