From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Zack Weinberg <zackw@panix.com>
Cc: Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>,
Siddhesh Poyarekar <siddhesh@gotplt.org>,
GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH v3 2/2] posix: Implement preadv2 and pwritev2
Date: Fri, 02 Jun 2017 18:20:00 -0000 [thread overview]
Message-ID: <f9508771-891d-090e-49e8-b4e85a0f6f77@linaro.org> (raw)
In-Reply-To: <CAKCAbMgAuA0-Zc1n_BwjGW767semHr-ApjUWecCo4h9gJk=unQ@mail.gmail.com>
On 02/06/2017 11:22, Zack Weinberg wrote:
> On Fri, Jun 2, 2017 at 10:07 AM, Adhemerval Zanella
> <adhemerval.zanella@linaro.org> wrote:
>>
>>
>> On 02/06/2017 10:34, Florian Weimer wrote:
>>> On 06/02/2017 03:04 PM, Zack Weinberg wrote:
>>>> I see this as well, for both tst-preadvwritev2 and
>>>> tst-preadvwritev64v2 on my x86-64 machine (kernel 4.9). Like HJ, if I
>>>> run the test manually, it succeeds.
>>>
>>> I see this on x86-64.
>>>
>>> pwritev2(3,
>>> [{iov_base="\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360",
>>> iov_len=32},
>>> {iov_base="\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17"...,
>>> iov_len=64}], 2, 0, 0x30 /* RWF_??? */) = -1 EOPNOTSUPP (Operation not
>>> supported)
>>>
>>> On a kernel which supports pwritev2 in general. I do not know yet where
>>> the 0x30 comes from.
>>>
>>> Florian
>>>
>>
>> This one still puzzles me, on 4.10.0 with gcc 6.3.0 I am seeing:
>>
>> [...]
>> [pid 28447] setpgid(0, 0) = 0
>> [pid 28447] pwritev2(3, [{"\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360", 32}, {"\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17"..., 64}], 2, 0, 0) = 96
>> [pid 28447] pwritev2(3, [{"\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360", 32}, {"\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17"..., 64}], 2, 96, 0) = 96
>> [pid 28447] preadv2(3, [{"\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360", 32}, {"\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17"..., 64}], 2, 0, 0) = 96
>> [pid 28447] preadv2(3, [{"\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360\360", 32}, {"\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17\17"..., 64}], 2, 96, 0) = 96
>> [pid 28447] getpid() = 28447
>> [...]
>>
>> This only issue I can think of is something very fuzzy in test build or a miscompilation.
>
> There's gotta be something wonky with the argument passing. Maybe try
> running the test case under valgrind? Also this trick often helps
> when a failure goes away when you run it manually:
>
> export CHANGE_SIZE_OF_ENV=""
> while
> the-command-that-should-fail
> do
> CHANGE_SIZE_OF_ENV="${CHANGE_SIZE_OF_ENV}x"
> echo -n .
> done; echo
>
> zw
>
I am even more confident this is indeed a miscompilation from GCC7 branch.
Using a previous built x86_64-linux-gnu with GCC6 branch I saw no issue, however
using GCC7 there is indeed the test failure. And it seems to show only for kernels
with support for p{read,write}v2 syscall, which means it stress the default
SYSCALL_CANCEL path.
However, running a GCC6 built testcase with a GCC7 build glibc (with testrun.sh)
I saw no issue. The GCC7 built test also fails with a GCC6 built glibc. I will
check with GCC master to see if this is something only on GCC7 branch or if it
is still on master.
Also, I seems that for GCC7 only x86_64-linux-gnu is affect on x86.
next prev parent reply other threads:[~2017-06-02 18:20 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-04 12:43 [PATCH v2 1/2] manual: Add preadv and pwritev documentation Adhemerval Zanella
2017-05-04 12:43 ` [PATCH v3 2/2] posix: Implement preadv2 and pwritev2 Adhemerval Zanella
2017-05-11 19:02 ` Adhemerval Zanella
2017-05-30 14:19 ` Adhemerval Zanella
2017-05-31 18:51 ` Adhemerval Zanella
2017-06-01 16:40 ` Siddhesh Poyarekar
2017-06-01 18:14 ` Adhemerval Zanella
2017-06-02 13:00 ` H.J. Lu
2017-06-02 13:04 ` Zack Weinberg
2017-06-02 13:34 ` Florian Weimer
2017-06-02 14:07 ` Adhemerval Zanella
2017-06-02 14:22 ` Zack Weinberg
2017-06-02 18:20 ` Adhemerval Zanella [this message]
2017-06-02 19:02 ` Florian Weimer
2017-06-02 19:46 ` Adhemerval Zanella
2017-06-03 1:47 ` H.J. Lu
2017-06-03 8:22 ` Andreas Schwab
2017-06-03 11:04 ` H.J. Lu
2017-06-03 11:23 ` Florian Weimer
2017-06-03 11:27 ` H.J. Lu
2017-06-03 11:29 ` H.J. Lu
2017-06-03 12:52 ` Andreas Schwab
2017-06-03 12:57 ` H.J. Lu
2017-06-03 13:48 ` Zack Weinberg
2017-06-03 13:52 ` H.J. Lu
2017-06-03 13:58 ` Zack Weinberg
2017-06-03 14:16 ` H.J. Lu
2017-06-03 15:28 ` Andreas Schwab
2017-06-04 13:42 ` H.J. Lu
2017-06-04 15:03 ` Zack Weinberg
2017-06-05 13:37 ` Adhemerval Zanella
2017-06-02 13:04 ` Tulio Magno Quites Machado Filho
2017-06-02 14:04 ` Adhemerval Zanella
2017-05-04 12:51 ` [PATCH v2 1/2] manual: Add preadv and pwritev documentation Florian Weimer
2017-05-04 13:47 ` Adhemerval Zanella
2017-05-04 18:46 ` Adhemerval Zanella
2017-05-04 18:46 ` Florian Weimer
2017-05-04 18:53 ` Adhemerval Zanella
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