From: Bakul Shah <bakul@iitbombay.org>
To: 9fans <9fans@9fans.net>
Subject: Re: [9fans] v9fs vs mmap (not quite SOLVED)
Date: Wed, 27 Oct 2021 08:02:41 -0700 [thread overview]
Message-ID: <8590FACA-50B2-4FF8-8B5F-AF0B5ABE1EA6@iitbombay.org> (raw)
In-Reply-To: <811fe89f74db52b9e1eaee440967c8dd@hamnavoe.com>
On Oct 27, 2021, at 3:55 AM, Richard Miller <9fans@hamnavoe.com> wrote:
>> Skip, did you specify -o cache=mmap when mounting diod service
>> for the go build experiment?
>
> I tried it myself using local diod and cache=mmap. I get a similar
> SIGBUS on instruction fetch again. Conclusion: as Bakul says, now
> I'm debugging linux. Not going there, thanks.
Looks like you are going there? :-)
> Going further off-topic for 9fans, sorry:
>
> I thought it would be clever to update the linux client to a newer
> kernel (4.19 was the latest I could find for debian 9). That
> didn't go well: booting the new kernel fails with the message
> Failed to find cpu0 device node
>
> Does anyone know if it's feasible to do an out-of-tree build
> of v9fs kernel modules (9p, 9pnet?) from current source [where
> is it?] and use them with my old 4.9 kernel?
May be this will help?
https://itnext.io/a-standalone-linux-kernel-module-df54283d4803
Though may you first want to start looking at the output of
git log github.com/torvalds/linux/fs/9p/vfs_file.c
grep for mmap related changes and check the code around changes
to see if you can spot the bug. The last mmap mention in the log
makes me wonder whether you see a difference in a 32 bit wordsize
machine vs 64 bit. May also be worth just talking to the folks
who worked on this feature.
A long time ago I wrote an mmap example C program that works on
anonymous maps (just steps through memory given some stride and
allocates memory in the signal handler on page faults). Something
similar can be written to access an mmapped file and tweaked
until your bug appears. Currently my program compiles on freebsd
but not linux (ubuntu). I will see if I can make it work.
------------------------------------------
9fans: 9fans
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next prev parent reply other threads:[~2021-10-27 15:02 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-24 11:03 [9fans] v9fs vs mmap Richard Miller
2021-10-24 19:50 ` [9fans] v9fs vs mmap (SOLVED) Richard Miller
2021-10-24 22:31 ` Conor Williams
2021-10-25 11:04 ` [9fans] v9fs vs mmap (not quite SOLVED) Richard Miller
2021-10-25 23:53 ` Conor Williams
2021-10-26 9:22 ` Richard Miller
2021-10-26 10:51 ` Richard Miller
2021-10-26 15:53 ` Dan Cross
2021-10-26 16:06 ` Conor Williams
2021-10-26 16:51 ` Richard Miller
2021-10-26 18:17 ` Skip Tavakkolian
2021-10-26 18:54 ` Conor Williams
2021-10-26 19:09 ` Richard Miller
2021-10-26 19:33 ` Skip Tavakkolian
2021-10-26 19:36 ` Skip Tavakkolian
2021-10-26 23:45 ` Skip Tavakkolian
2021-10-26 23:57 ` Charles Forsyth
2021-10-27 8:27 ` Richard Miller
2021-10-27 10:55 ` Richard Miller
2021-10-27 12:31 ` Dan Cross
2021-10-27 13:15 ` Richard Miller
2021-10-27 13:20 ` Dan Cross
2021-10-27 14:10 ` Richard Miller
2021-10-27 14:14 ` arnold
2021-10-27 14:39 ` Richard Miller
2021-10-27 14:45 ` arnold
2021-10-27 14:31 ` Dan Cross
2021-10-27 15:02 ` Bakul Shah [this message]
2021-10-27 15:37 ` Charles Forsyth
2021-10-27 16:34 ` Skip Tavakkolian
2021-10-27 18:37 ` Richard Miller
2021-10-27 19:12 ` Skip Tavakkolian
2021-10-27 19:30 ` [9fans] v9fs vs mmap (now SOLVED, we hope) Richard Miller
2021-10-27 20:18 ` Skip Tavakkolian
2021-11-03 14:44 ` Conor Williams
2021-11-03 16:39 ` Conor Williams
2021-11-01 2:58 ` [9fans] v9fs vs mmap (not quite SOLVED) Conor Williams
2021-11-04 0:32 ` Conor Williams
2021-11-04 3:15 ` Conor Williams
2021-11-04 11:49 ` Conor Williams
2021-11-05 3:16 ` Conor Williams
2021-11-05 10:21 ` Kenji Okamoto
2021-11-05 13:44 ` Conor Williams
2021-11-05 13:56 ` Conor Williams
2021-11-21 4:21 ` Conor Williams
2021-10-27 0:34 ` Conor Williams
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