linux-kernel - Re: [PATCH] coredump: fix pipe coredump when core limit is 0

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Message-ID: <CACV3sbLJFwajVQuYfAYW9mt6tm8zeMa-ctKGyGq+qnXtWxFeCA@mail.gmail.com>
Date:	Wed, 24 Aug 2011 18:17:10 +0800
From:	Jovi Zhang <bookjovi@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Pádraig Brady <P@...igbrady.com>,
	Neil Horman <nhorman@...driver.com>, dhowells@...hat.com,
	roland@...hat.com, viro@...iv.linux.org.uk,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] coredump: fix pipe coredump when core limit is 0

On Wed, Aug 24, 2011 at 6:14 PM, Jovi Zhang <bookjovi@...il.com> wrote:
> 2011/8/23 Oleg Nesterov <oleg@...hat.com>:
>> On 08/22, Pádraig Brady wrote:
>>>
>>> On 08/21/2011 11:36 PM, Neil Horman wrote:
>>> > Concur.  The comment should be changed
>>> > Neil
>>> >
>>> > Oleg Nesterov <oleg@...hat.com> wrote:
>>> >
>>> >> On 08/21, Oleg Nesterov wrote:
>>> >>>
>>> >>> On 08/21, bookjovi@...il.com wrote:
>>> >>>>
>>> >>>> For non-pipe case, limit 0 also means drop the coredump, so just put
>>> >>>> the zero limit check at do_coredump function begining.
>>> >>>
>>> >>> Neil, what do you think? Should we change the code or the comment?
>>> >>
>>> >> Personally I think we should fix the comment. I think RLIMIT_CORE
>>> >> doesn't apply in this case, limit == 1 check is very special. And
>>> >> this is what linux always did, except between 725eae32 and 898b374a.
>>>
>>> Sorry for jumping in late here.
>>> I would really like `ulimit -c 0` to completely disable core dumps,
>>> including not running core_pattern, as I also mentioned here:
>>> https://bugs.launchpad.net/ubuntu/+source/apport/+bug/62511
>>> I noticed this in a script where ctrl-\ was taking a long
>>> time to be registered as the core_pattern was run unconditionally.
>>
>> May be. As I said, I do not really know and personally I agree with
>> everything. My only point was, this is not the bug, this is what we
>> always did.
>>
>> This is up to Neil, I think.
>>
>> Oleg.
>>
>>
> Well, so here have two questions.
> 1) That comments "but a limit of 0 skips the dump" definitely is wrong
> right now, it don't match with reality.
> 2) In ispipe case, core limit 0 should skip the dump or not? this need
> more discussion.
>    from pipe coredump point of view, core limit is irrelevant, it
> doesn't write to file system.
>    from user point of view, there will be a lot of core files if we
> let core limit 0 create core file, user might be boring.
>
> I fix the comments part by below patch(thanks Oleg's comments), please
> use attachment patch when merge.
>

Patch attached.

Download attachment "0001-coredump-fix-wrong-comments-on-core-limits-of-pipe-c.patch" of type "application/octet-stream" (1761 bytes)