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 B90C92773E3; Wed, 8 Oct 2025 20:05:12 +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=1759953912; cv=none; b=YXMPn66d5u10EMVQps9VO4w8R4fnjRlH955SzsBUwTZiEssyrPwk11Zt+z0pDdEB0HoLXq0dStwxIrpj54+3ZT7UHGIZxte4q0+tg/lAhbpuI7NUkblFe5gLgS0GgW8LNrzKB+C4v6uksgfYWLq5oU30NsOO2eEaVIM7vCYHa24= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759953912; c=relaxed/simple; bh=dC9R5uPZRb8FYi2xCT/Fs6uMB1LxYeB1rdgOthG8uEg=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Q6N21CpUHb50LArr0ppY/Au6al1QrmwSvFpMXnZ7yoKC71YSWYX8kVyKUL1m7x7G1OWxPr27XQc+ZzgMWECLqyRMM3PSRTJgnCn3UgnlEEFjO10Vwr6Nh4KJF6SMabIqWIc2otBS5dN2E5kDW+ReqKXnRnR4g5Su9lm7rwo91p4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=i/L3Mp6H; 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="i/L3Mp6H" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 025C8C4CEE7; Wed, 8 Oct 2025 20:05:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759953912; bh=dC9R5uPZRb8FYi2xCT/Fs6uMB1LxYeB1rdgOthG8uEg=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=i/L3Mp6H8f1HBHZiBEr6GNBhEnLPpLOX7Gh3CBNFFpMi5gvWaUCeGgsP74NjG+0Gf 685Qgu4zvcrO97qB/19kz8DVVfrMp+0ArrfrHLh2UMiEYbkyiEI+tgsuy3crKUwUhE vfzl2k+81aFc3bghC2oJx2SHS7PxuQOkpP+jf2eKNdNfsawoOLlrpN5BRHSHyKhd2T asxIoBH+zev4c1LM7USRzXHgKMXnyBor5qjMBBeCnkKrTQuXeO5CQMR5ZqP1u3WSgv Iil2Te/+MciJImBg+bNG03OEfd2Je+kHgYcVK5ITezgLm6PahBGVFb1V1Xm8uLg7+m yrgUu2IL24iEg== Message-ID: Subject: Re: [PATCH 2/2] sunrpc: add a slot to rqstp->rq_bvec for TCP record marker From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Trond Myklebust , Anna Schumaker , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , David Howells Cc: linux-nfs@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Mike Snitzer , brandona@meta.com Date: Wed, 08 Oct 2025 16:05:08 -0400 In-Reply-To: <20251008-rq_bvec-v1-2-7f23d32d75e5@kernel.org> References: <20251008-rq_bvec-v1-0-7f23d32d75e5@kernel.org> <20251008-rq_bvec-v1-2-7f23d32d75e5@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 YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn 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DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-10-08 at 14:58 -0400, Jeff Layton wrote: > svc_tcp_sendmsg steals a slot in the rq_bvec array for the TCP record > marker. If the send is an unaligned READ call though, then there may not > be enough slots in the rq_bvec array. >=20 > Add a slot to the rq_bvec array, and fix up the array length > calculations. >=20 > Fixes: e18e157bb5c8 ("SUNRPC: Send RPC message on TCP with a single sock_= sendmsg() call") > Signed-off-by: Jeff Layton > --- > fs/nfsd/vfs.c | 6 +++--- > net/sunrpc/svc.c | 3 ++- > net/sunrpc/svcsock.c | 4 ++-- > 3 files changed, 7 insertions(+), 6 deletions(-) >=20 > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c > index 77f6879c2e063fa79865100bbc2d1e64eb332f42..c4e9300d657cf7fdba23f2f4e= 4bdaad9cd99d1a3 100644 > --- a/fs/nfsd/vfs.c > +++ b/fs/nfsd/vfs.c > @@ -1111,7 +1111,7 @@ nfsd_direct_read(struct svc_rqst *rqstp, struct svc= _fh *fhp, > =20 > v =3D 0; > total =3D dio_end - dio_start; > - while (total && v < rqstp->rq_maxpages && > + while (total && v < rqstp->rq_maxpages + 1 && > rqstp->rq_next_page < rqstp->rq_page_end) { > len =3D min_t(size_t, total, PAGE_SIZE); > bvec_set_page(&rqstp->rq_bvec[v], *rqstp->rq_next_page, > @@ -1200,7 +1200,7 @@ __be32 nfsd_iter_read(struct svc_rqst *rqstp, struc= t svc_fh *fhp, > =20 > v =3D 0; > total =3D *count; > - while (total && v < rqstp->rq_maxpages && > + while (total && v < rqstp->rq_maxpages + 1 && > rqstp->rq_next_page < rqstp->rq_page_end) { > len =3D min_t(size_t, total, PAGE_SIZE - base); > bvec_set_page(&rqstp->rq_bvec[v], *rqstp->rq_next_page, > @@ -1318,7 +1318,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_f= h *fhp, > if (stable && !fhp->fh_use_wgather) > kiocb.ki_flags |=3D IOCB_DSYNC; > =20 > - nvecs =3D xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, payload); > + nvecs =3D xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages + 1, paylo= ad); > iov_iter_bvec(&iter, ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt); > since =3D READ_ONCE(file->f_wb_err); > if (verf) > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > index 4704dce7284eccc9e2bc64cf22947666facfa86a..919263a0c04e3f1afa607414b= c1893ba02206e38 100644 > --- a/net/sunrpc/svc.c > +++ b/net/sunrpc/svc.c > @@ -706,7 +706,8 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_= pool *pool, int node) > if (!svc_init_buffer(rqstp, serv, node)) > goto out_enomem; > =20 > - rqstp->rq_bvec =3D kcalloc_node(rqstp->rq_maxpages, > + /* +1 for the TCP record marker */ > + rqstp->rq_bvec =3D kcalloc_node(rqstp->rq_maxpages + 1, > sizeof(struct bio_vec), > GFP_KERNEL, node); > if (!rqstp->rq_bvec) > diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c > index 377fcaaaa061463fc5c85fc09c7a8eab5e06af77..5f8bb11b686bcd7302b944764= 90ba9b1b9ddc06a 100644 > --- a/net/sunrpc/svcsock.c > +++ b/net/sunrpc/svcsock.c > @@ -740,7 +740,7 @@ static int svc_udp_sendto(struct svc_rqst *rqstp) > if (svc_xprt_is_dead(xprt)) > goto out_notconn; > =20 > - count =3D xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, xdr); > + count =3D xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages + 1, xdr); > =20 > iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec, > count, rqstp->rq_res.len); > @@ -1244,7 +1244,7 @@ static int svc_tcp_sendmsg(struct svc_sock *svsk, s= truct svc_rqst *rqstp, > memcpy(buf, &marker, sizeof(marker)); > bvec_set_virt(rqstp->rq_bvec, buf, sizeof(marker)); > =20 > - count =3D xdr_buf_to_bvec(rqstp->rq_bvec + 1, rqstp->rq_maxpages - 1, > + count =3D xdr_buf_to_bvec(rqstp->rq_bvec + 1, rqstp->rq_maxpages, > &rqstp->rq_res); > =20 > iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec, Mike suggested that we add more info to the changelog that will actually get committed to the kernel. How about this? -----------------------------8<--------------------------- sunrpc: add a slot to rqstp->rq_bvec for TCP record marker =20 We've seen some occurrences of messages like this in dmesg on some knfs= d servers: =20 xdr_buf_to_bvec: bio_vec array overflow =20 Usually followed by messages like this that indicate a short send: =20 rpc-srv/tcp: nfsd: sent 1048155 when sending 1048152 bytes - shutti= ng down socket =20 svc_tcp_sendmsg() steals a slot in the rq_bvec array for the TCP record marker. If the send is an unaligned READ call though, then there may no= t be enough slots in the rq_bvec array in some cases. =20 Add a slot to the rq_bvec array, and fix up the array lengths in the callers that care. =20 Fixes: e18e157bb5c8 ("SUNRPC: Send RPC message on TCP with a single soc= k_sendmsg() call") Tested-by: Brandon Adams Signed-off-by: Jeff Layton -----------------------------8<--------------------------- --=20 Jeff Layton