On 02/14/2016 07:02 PM, Alex McWhirter wrote:
> I having a strange issue where using any 4.X kernel causes rsync to
> appear to die on a select syscall. Not sure why, maybe it's getting a
> wrong file descriptor or something. Unfortunately this starts pushing
> outside of my knowledge level of linux so bear with me. This is on a Sun
> V215 but i have also tested it on a Sun Blade 150 and a Sun Ultra 45
> with the same results. These are all sun4u boxes of course, i haven't
> tried any sun4v boxes. I''l try to spin up a T5120 this week and find
> out if it's also an issue on sun4v.
>
> Here's what I've tested.
>
> 3.14.58 "gentoo" - Works
> 3.18.26 "vanilla" - Works
> 4.1.15 "gentoo" - Dead
> 4.1.17 "vanilla" - Dead
> 4.4.1 "vanilla" - Dead
>
> I don't mind hacking away at kernel sources if anyone can point me in
> the right direction. It's also worth noting that this only happens when
> the folder i am attempting to rsync is significantly large in regards to
> the amount of sub-folders and files. The Gentoo portage tree in particular.
>
> Attached is the strace output of a failing rsync job.
>
>
I've traced this down a bit further.
Kernel 3.18.26 is working but 3.19.0 is not. Git bisect traced it down
to this commit.
e5a4b0bb803b39a36478451eae53a880d2663d5b is the first bad commit
commit e5a4b0bb803b39a36478451eae53a880d2663d5b
Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Mon Nov 24 18:17:55 2014 -0500
switch memcpy_to_msg() and skb_copy{,_and_csum}_datagram_msg() to
primitives
... making both non-draining. That means that tcp_recvmsg() becomes
non-draining. And _that_ would break iscsit_do_rx_data() unless we
a) make sure tcp_recvmsg() is uniformly non-draining (it is)
b) make sure it copes with arbitrary (including shifted)
iov_iter (it does, all it uses is iov_iter primitives)
c) make iscsit_do_rx_data() initialize ->msg_iter only once.
Fortunately, (c) is doable with minimal work and we are rid of one
the two places where kernel send/recvmsg users would be unhappy with
non-draining behaviour.
Actually, that makes all but one of ->recvmsg() instances
iov_iter-clean.
The exception is skcipher_recvmsg() and it also isn't hard to convert
to primitives (iov_iter_get_pages() is needed there). That'll wait
a bit - there's some interplay with ->sendmsg() path for that one.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
:040000 040000 b4d6852e73bd3d54a30b72441c8e35f79dc07266
f0b90ef68ee891b38decf571247002c1d7fad519 M drivers
:040000 040000 8ba2fadf14c05a86a7c21448dac52fed661a2e12
0051ec4b6f273dbaed2bed21e4fddd48664d5afa M include
:040000 040000 d28e72369891521f7d853b30612a32cf65a27f6b
b828e68082a6fed2cf240aad4b365c5808928122 M net
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