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From: Vivek Goyal <vgoyal@redhat.com>
To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Baoquan He <bhe@redhat.com>,
	Kexec Mailing List <kexec@lists.infradead.org>,
	linux kernel mailing list <linux-kernel@vger.kernel.org>,
	Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Dave Young <dyoung@redhat.com>, WANG Chao <chaowang@redhat.com>
Subject: Re: /proc/vmcore mmap() failure issue
Date: Fri, 15 Nov 2013 09:26:17 -0500	[thread overview]
Message-ID: <20131115142617.GC6637@redhat.com> (raw)
In-Reply-To: <5285EC60.1060906@jp.fujitsu.com>

On Fri, Nov 15, 2013 at 06:41:52PM +0900, HATAYAMA Daisuke wrote:

[..]
> >Given the fact that hpa does not like fixing it in kernel. We are left
> >with option of fixing it in following places.
> >
> >- Drop partial pages in kexec-tools
> >- Drop partial pages in makeudmpfile.
> >- Read partial pages using read() interface in makedumpfile
> >- Modify /proc/vmcore to copy partial pages in second kernel's memory.
> >
> >It is not clear to me that partial pages are really useful.  So I want
> >to avoid modifying /proc/vmcore to deal with partial pages and increase
> >complexity.
> >
> >So fixing makedumpfile (either option2 or option 3) seems least risky
> >to me. In fact I would say let us keep it simple and truncate partial
> >pages in makedumpfile to keep it simple. And look at option 3 once we
> >have a strong use case for partial pages.
> >
> >What do you think?
> >
> 
> As you say, it's not clear that partial pages are really useful, but on
> the other hand, it seems to me not clear that they are really useless.
> I think we should get them as long as we have access to them.
> 
> It seems best to me the option 3). Switching between read and mmap would
> be not so complex and also it's by far flexible in makedumpfile than in
> kernel.

Ok, I am fine with option 3. It is more complicated option but safe
option.

Is there any chance that you could look into fixing this. I have no
experience writing code for makedumpfile.

Thanks
Vivek

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WARNING: multiple messages have this Message-ID (diff)
From: Vivek Goyal <vgoyal@redhat.com>
To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Baoquan He <bhe@redhat.com>,
	Kexec Mailing List <kexec@lists.infradead.org>,
	linux kernel mailing list <linux-kernel@vger.kernel.org>,
	Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Dave Young <dyoung@redhat.com>, WANG Chao <chaowang@redhat.com>
Subject: Re: /proc/vmcore mmap() failure issue
Date: Fri, 15 Nov 2013 09:26:17 -0500	[thread overview]
Message-ID: <20131115142617.GC6637@redhat.com> (raw)
In-Reply-To: <5285EC60.1060906@jp.fujitsu.com>

On Fri, Nov 15, 2013 at 06:41:52PM +0900, HATAYAMA Daisuke wrote:

[..]
> >Given the fact that hpa does not like fixing it in kernel. We are left
> >with option of fixing it in following places.
> >
> >- Drop partial pages in kexec-tools
> >- Drop partial pages in makeudmpfile.
> >- Read partial pages using read() interface in makedumpfile
> >- Modify /proc/vmcore to copy partial pages in second kernel's memory.
> >
> >It is not clear to me that partial pages are really useful.  So I want
> >to avoid modifying /proc/vmcore to deal with partial pages and increase
> >complexity.
> >
> >So fixing makedumpfile (either option2 or option 3) seems least risky
> >to me. In fact I would say let us keep it simple and truncate partial
> >pages in makedumpfile to keep it simple. And look at option 3 once we
> >have a strong use case for partial pages.
> >
> >What do you think?
> >
> 
> As you say, it's not clear that partial pages are really useful, but on
> the other hand, it seems to me not clear that they are really useless.
> I think we should get them as long as we have access to them.
> 
> It seems best to me the option 3). Switching between read and mmap would
> be not so complex and also it's by far flexible in makedumpfile than in
> kernel.

Ok, I am fine with option 3. It is more complicated option but safe
option.

Is there any chance that you could look into fixing this. I have no
experience writing code for makedumpfile.

Thanks
Vivek

  reply	other threads:[~2013-11-15 14:26 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-13 20:41 /proc/vmcore mmap() failure issue Vivek Goyal
2013-11-13 20:41 ` Vivek Goyal
2013-11-13 21:04 ` Vivek Goyal
2013-11-13 21:04   ` Vivek Goyal
2013-11-13 21:14   ` H. Peter Anvin
2013-11-13 21:14     ` H. Peter Anvin
2013-11-13 22:41     ` Vivek Goyal
2013-11-13 22:41       ` Vivek Goyal
2013-11-13 22:44       ` H. Peter Anvin
2013-11-13 22:44         ` H. Peter Anvin
2013-11-13 23:00         ` Vivek Goyal
2013-11-13 23:00           ` Vivek Goyal
2013-11-13 23:08           ` H. Peter Anvin
2013-11-13 23:08             ` H. Peter Anvin
2013-11-14 10:31 ` HATAYAMA Daisuke
2013-11-14 10:31   ` HATAYAMA Daisuke
2013-11-14 15:13   ` Vivek Goyal
2013-11-14 15:13     ` Vivek Goyal
2013-11-15  9:41     ` HATAYAMA Daisuke
2013-11-15  9:41       ` HATAYAMA Daisuke
2013-11-15 14:26       ` Vivek Goyal [this message]
2013-11-15 14:26         ` Vivek Goyal
2013-11-18  0:51         ` Atsushi Kumagai
2013-11-18  0:51           ` Atsushi Kumagai
2013-11-18 13:55           ` Vivek Goyal
2013-11-18 13:55             ` Vivek Goyal
2013-11-20  5:29             ` Atsushi Kumagai
2013-11-20  5:29               ` Atsushi Kumagai
2013-11-20 14:59               ` Vivek Goyal
2013-11-20 14:59                 ` Vivek Goyal
2013-11-21  5:00                 ` Atsushi Kumagai
2013-11-21  5:00                   ` Atsushi Kumagai
2013-11-21  8:31                   ` HATAYAMA Daisuke
2013-11-21  8:31                     ` HATAYAMA Daisuke
2013-11-21 16:52                     ` Vivek Goyal
2013-11-21 16:52                       ` Vivek Goyal
2013-11-25  8:10                       ` Atsushi Kumagai
2013-11-25  8:10                         ` Atsushi Kumagai
2013-11-25  9:01                         ` HATAYAMA Daisuke
2013-11-25  9:01                           ` HATAYAMA Daisuke
2013-11-25 14:41                           ` Vivek Goyal
2013-11-25 14:41                             ` Vivek Goyal
2013-11-26  1:51                             ` Atsushi Kumagai
2013-11-26  1:51                               ` Atsushi Kumagai
2013-11-26  5:16                             ` HATAYAMA Daisuke
2013-11-26  5:16                               ` HATAYAMA Daisuke
2013-11-19  9:55           ` HATAYAMA Daisuke
2013-11-19  9:55             ` HATAYAMA Daisuke
2013-11-20  5:27             ` Atsushi Kumagai
2013-11-20  5:27               ` Atsushi Kumagai
2013-11-20  6:43               ` HATAYAMA Daisuke
2013-11-20  6:43                 ` HATAYAMA Daisuke
2013-11-26  1:52                 ` Atsushi Kumagai
2013-11-26  1:52                   ` Atsushi Kumagai
2013-11-21  7:14               ` chaowang
2013-11-21  7:14                 ` chaowang
2013-11-25  8:09                 ` Atsushi Kumagai
2013-11-25  8:09                   ` Atsushi Kumagai
2013-11-26  3:29                   ` chaowang
2013-11-26  3:29                     ` chaowang

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