* [PATCH] SUNRPC: Flush dcache only when receiving more seeking
@ 2020-09-18 12:50 zhe.he
2020-09-18 16:23 ` Chuck Lever
0 siblings, 1 reply; 3+ messages in thread
From: zhe.he @ 2020-09-18 12:50 UTC (permalink / raw)
To: bfields, chuck.lever, trond.myklebust, anna.schumaker, davem,
kuba, linux-nfs, netdev, linux-kernel, zhe.he
From: He Zhe <zhe.he@windriver.com>
commit ca07eda33e01 ("SUNRPC: Refactor svc_recvfrom()") introduces
svc_flush_bvec to after sock_recvmsg, but sometimes we receive less than we
seek, which triggers the following warning.
WARNING: CPU: 0 PID: 18266 at include/linux/bvec.h:101 bvec_iter_advance+0x44/0xa8
Attempted to advance past end of bvec iter
Modules linked in: sch_fq_codel openvswitch nsh nf_conncount nf_nat
nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
CPU: 1 PID: 18266 Comm: nfsd Not tainted 5.9.0-rc5 #1
Hardware name: Xilinx Zynq Platform
[<80112ec0>] (unwind_backtrace) from [<8010c3a8>] (show_stack+0x18/0x1c)
[<8010c3a8>] (show_stack) from [<80755214>] (dump_stack+0x9c/0xd0)
[<80755214>] (dump_stack) from [<80125e64>] (__warn+0xdc/0xf4)
[<80125e64>] (__warn) from [<80126244>] (warn_slowpath_fmt+0x84/0xac)
[<80126244>] (warn_slowpath_fmt) from [<80c88514>] (bvec_iter_advance+0x44/0xa8)
[<80c88514>] (bvec_iter_advance) from [<80c88940>] (svc_tcp_read_msg+0x10c/0x1bc)
[<80c88940>] (svc_tcp_read_msg) from [<80c895d4>] (svc_tcp_recvfrom+0x98/0x63c)
[<80c895d4>] (svc_tcp_recvfrom) from [<80c97bf4>] (svc_handle_xprt+0x48c/0x4f8)
[<80c97bf4>] (svc_handle_xprt) from [<80c98038>] (svc_recv+0x94/0x1e0)
[<80c98038>] (svc_recv) from [<804747cc>] (nfsd+0xf0/0x168)
[<804747cc>] (nfsd) from [<80148a0c>] (kthread+0x144/0x154)
[<80148a0c>] (kthread) from [<80100114>] (ret_from_fork+0x14/0x20)
Fixes: ca07eda33e01 ("SUNRPC: Refactor svc_recvfrom()")
Cc: <stable@vger.kernel.org> # 5.8+
Signed-off-by: He Zhe <zhe.he@windriver.com>
---
net/sunrpc/svcsock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index d5805fa1d066..ea3bc9635448 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -277,7 +277,7 @@ static ssize_t svc_tcp_read_msg(struct svc_rqst *rqstp, size_t buflen,
buflen -= seek;
}
len = sock_recvmsg(svsk->sk_sock, &msg, MSG_DONTWAIT);
- if (len > 0)
+ if (len > (seek & PAGE_MASK))
svc_flush_bvec(bvec, len, seek);
/* If we read a full record, then assume there may be more
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] SUNRPC: Flush dcache only when receiving more seeking
2020-09-18 12:50 [PATCH] SUNRPC: Flush dcache only when receiving more seeking zhe.he
@ 2020-09-18 16:23 ` Chuck Lever
2020-09-19 13:15 ` He Zhe
0 siblings, 1 reply; 3+ messages in thread
From: Chuck Lever @ 2020-09-18 16:23 UTC (permalink / raw)
To: zhe.he
Cc: Bruce Fields, Trond Myklebust, Anna Schumaker, David S . Miller,
Jakub Kicinski, Linux NFS Mailing List,
open list:NETWORKING DRIVERS, linux-kernel
> On Sep 18, 2020, at 8:50 AM, zhe.he@windriver.com wrote:
>
> From: He Zhe <zhe.he@windriver.com>
>
> commit ca07eda33e01 ("SUNRPC: Refactor svc_recvfrom()") introduces
> svc_flush_bvec to after sock_recvmsg, but sometimes we receive less than we
> seek, which triggers the following warning.
>
> WARNING: CPU: 0 PID: 18266 at include/linux/bvec.h:101 bvec_iter_advance+0x44/0xa8
> Attempted to advance past end of bvec iter
> Modules linked in: sch_fq_codel openvswitch nsh nf_conncount nf_nat
> nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
> CPU: 1 PID: 18266 Comm: nfsd Not tainted 5.9.0-rc5 #1
> Hardware name: Xilinx Zynq Platform
> [<80112ec0>] (unwind_backtrace) from [<8010c3a8>] (show_stack+0x18/0x1c)
> [<8010c3a8>] (show_stack) from [<80755214>] (dump_stack+0x9c/0xd0)
> [<80755214>] (dump_stack) from [<80125e64>] (__warn+0xdc/0xf4)
> [<80125e64>] (__warn) from [<80126244>] (warn_slowpath_fmt+0x84/0xac)
> [<80126244>] (warn_slowpath_fmt) from [<80c88514>] (bvec_iter_advance+0x44/0xa8)
> [<80c88514>] (bvec_iter_advance) from [<80c88940>] (svc_tcp_read_msg+0x10c/0x1bc)
> [<80c88940>] (svc_tcp_read_msg) from [<80c895d4>] (svc_tcp_recvfrom+0x98/0x63c)
> [<80c895d4>] (svc_tcp_recvfrom) from [<80c97bf4>] (svc_handle_xprt+0x48c/0x4f8)
> [<80c97bf4>] (svc_handle_xprt) from [<80c98038>] (svc_recv+0x94/0x1e0)
> [<80c98038>] (svc_recv) from [<804747cc>] (nfsd+0xf0/0x168)
> [<804747cc>] (nfsd) from [<80148a0c>] (kthread+0x144/0x154)
> [<80148a0c>] (kthread) from [<80100114>] (ret_from_fork+0x14/0x20)
>
> Fixes: ca07eda33e01 ("SUNRPC: Refactor svc_recvfrom()")
> Cc: <stable@vger.kernel.org> # 5.8+
> Signed-off-by: He Zhe <zhe.he@windriver.com>
> ---
> net/sunrpc/svcsock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
> index d5805fa1d066..ea3bc9635448 100644
> --- a/net/sunrpc/svcsock.c
> +++ b/net/sunrpc/svcsock.c
> @@ -277,7 +277,7 @@ static ssize_t svc_tcp_read_msg(struct svc_rqst *rqstp, size_t buflen,
> buflen -= seek;
> }
> len = sock_recvmsg(svsk->sk_sock, &msg, MSG_DONTWAIT);
> - if (len > 0)
> + if (len > (seek & PAGE_MASK))
I don't understand how this addresses the WARNING. Can you provide
an example set of inputs that trigger the issue?
Also this change introduces a mixed-sign comparison, so NACK on
this particular patch unless it can be demonstrated that the
implicit type conversion here is benign (I don't think it is,
but I haven't thought through it).
> svc_flush_bvec(bvec, len, seek);
>
> /* If we read a full record, then assume there may be more
> --
> 2.17.1
>
--
Chuck Lever
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] SUNRPC: Flush dcache only when receiving more seeking
2020-09-18 16:23 ` Chuck Lever
@ 2020-09-19 13:15 ` He Zhe
0 siblings, 0 replies; 3+ messages in thread
From: He Zhe @ 2020-09-19 13:15 UTC (permalink / raw)
To: Chuck Lever
Cc: Bruce Fields, Trond Myklebust, Anna Schumaker, David S . Miller,
Jakub Kicinski, Linux NFS Mailing List,
open list:NETWORKING DRIVERS, linux-kernel
On 9/19/20 12:23 AM, Chuck Lever wrote:
>
>> On Sep 18, 2020, at 8:50 AM, zhe.he@windriver.com wrote:
>>
>> From: He Zhe <zhe.he@windriver.com>
>>
>> commit ca07eda33e01 ("SUNRPC: Refactor svc_recvfrom()") introduces
>> svc_flush_bvec to after sock_recvmsg, but sometimes we receive less than we
>> seek, which triggers the following warning.
>>
>> WARNING: CPU: 0 PID: 18266 at include/linux/bvec.h:101 bvec_iter_advance+0x44/0xa8
>> Attempted to advance past end of bvec iter
>> Modules linked in: sch_fq_codel openvswitch nsh nf_conncount nf_nat
>> nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
>> CPU: 1 PID: 18266 Comm: nfsd Not tainted 5.9.0-rc5 #1
>> Hardware name: Xilinx Zynq Platform
>> [<80112ec0>] (unwind_backtrace) from [<8010c3a8>] (show_stack+0x18/0x1c)
>> [<8010c3a8>] (show_stack) from [<80755214>] (dump_stack+0x9c/0xd0)
>> [<80755214>] (dump_stack) from [<80125e64>] (__warn+0xdc/0xf4)
>> [<80125e64>] (__warn) from [<80126244>] (warn_slowpath_fmt+0x84/0xac)
>> [<80126244>] (warn_slowpath_fmt) from [<80c88514>] (bvec_iter_advance+0x44/0xa8)
>> [<80c88514>] (bvec_iter_advance) from [<80c88940>] (svc_tcp_read_msg+0x10c/0x1bc)
>> [<80c88940>] (svc_tcp_read_msg) from [<80c895d4>] (svc_tcp_recvfrom+0x98/0x63c)
>> [<80c895d4>] (svc_tcp_recvfrom) from [<80c97bf4>] (svc_handle_xprt+0x48c/0x4f8)
>> [<80c97bf4>] (svc_handle_xprt) from [<80c98038>] (svc_recv+0x94/0x1e0)
>> [<80c98038>] (svc_recv) from [<804747cc>] (nfsd+0xf0/0x168)
>> [<804747cc>] (nfsd) from [<80148a0c>] (kthread+0x144/0x154)
>> [<80148a0c>] (kthread) from [<80100114>] (ret_from_fork+0x14/0x20)
>>
>> Fixes: ca07eda33e01 ("SUNRPC: Refactor svc_recvfrom()")
>> Cc: <stable@vger.kernel.org> # 5.8+
>> Signed-off-by: He Zhe <zhe.he@windriver.com>
>> ---
>> net/sunrpc/svcsock.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
>> index d5805fa1d066..ea3bc9635448 100644
>> --- a/net/sunrpc/svcsock.c
>> +++ b/net/sunrpc/svcsock.c
>> @@ -277,7 +277,7 @@ static ssize_t svc_tcp_read_msg(struct svc_rqst *rqstp, size_t buflen,
>> buflen -= seek;
>> }
>> len = sock_recvmsg(svsk->sk_sock, &msg, MSG_DONTWAIT);
>> - if (len > 0)
>> + if (len > (seek & PAGE_MASK))
> I don't understand how this addresses the WARNING. Can you provide
> an example set of inputs that trigger the issue?
I was trying to meet the not warning condition in bvec_iter_advance to make
the flushing meaningful.
svc_flush_bvec
bvec_iter_advance
WARN_ONCE(bytes > iter->bi_size,...
Here are my steps:
mkdir /root/mount_point/
mount /dev/sda1 /root/mount_point/
systemctl restart nfs-server
exportfs
mount -vvv -t nfs 127.0.0.1:/root/mount_point/ /mnt
cp /bin/bash ./bash.tmp
>
> Also this change introduces a mixed-sign comparison, so NACK on
> this particular patch unless it can be demonstrated that the
> implicit type conversion here is benign (I don't think it is,
> but I haven't thought through it).
Thanks, I didn't notice the different types. What about this?
if (len > 0 && (size_t)len > (seek & PAGE_MASK))
Zhe
>
>
>> svc_flush_bvec(bvec, len, seek);
>>
>> /* If we read a full record, then assume there may be more
>> --
>> 2.17.1
>>
> --
> Chuck Lever
>
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-09-19 13:15 UTC | newest]
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2020-09-18 12:50 [PATCH] SUNRPC: Flush dcache only when receiving more seeking zhe.he
2020-09-18 16:23 ` Chuck Lever
2020-09-19 13:15 ` He Zhe
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