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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>,
	Vlastimil Babka <vbabka@suse.cz>,
	linux-kernel@vger.kernel.org,  Linux-MM <linux-mm@kvack.org>,
	Helge Deller <deller@gmx.de>,
	linux-parisc@vger.kernel.org
Subject: Re: [PATCH 6.10 000/809] 6.10.3-rc3 review
Date: Thu, 8 Aug 2024 11:19:51 -0700	[thread overview]
Message-ID: <CAHk-=wiZUidi6Gm_6XFArT621H7vAzhDA63zn2pSGJHdnjRCMA@mail.gmail.com> (raw)
In-Reply-To: <8734nezz0g.ffs@tglx>

On Thu, 8 Aug 2024 at 10:48, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Here is the disassembly from my latest crashing debug kernel which
> shifts it up a couple of pages. Add 0x10 or sub 0x20 to make it work.

Looks like I was off by an instruction, it's the 28th divide-step (not
29) that does the page crosser:

>     4121dffc:   0b 21 04 41     ds r1,r25,r1
>     4121e000:   0b bd 07 1d     add,c ret1,ret1,ret1

but my parisc knowledge is not good enough to even guess at what could go wrong.

And I have no actual reason to believe this has *anything* to do with
an itlb miss, except for that whole "exact placement seems to matter,
and it crosses a page boundary" detail.

None of this makes sense. I think we'll have to wait for Helge. It's
not like parisc is a huge concern, and for all we know this is all a
qemu bug to begin with.

          Linus


  reply	other threads:[~2024-08-08 18:20 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20240731095022.970699670@linuxfoundation.org>
     [not found] ` <718b8afe-222f-4b3a-96d3-93af0e4ceff1@roeck-us.net>
2024-08-06  2:40   ` Linus Torvalds
2024-08-06 11:02     ` Vlastimil Babka
2024-08-06 17:33       ` Thomas Gleixner
     [not found]         ` <90e02d99-37a2-437e-ad42-44b80c4e94f6@suse.cz>
     [not found]           ` <87frrh44mf.ffs@tglx>
     [not found]             ` <76c643ee-17d6-463b-8ee1-4e30b0133671@roeck-us.net>
     [not found]               ` <87plqjz6aa.ffs@tglx>
2024-08-08 15:53                 ` Linus Torvalds
2024-08-08 16:12                   ` Thomas Gleixner
2024-08-08 16:33                     ` Linus Torvalds
2024-08-08 17:48                       ` Thomas Gleixner
2024-08-08 18:19                         ` Linus Torvalds [this message]
2024-08-08 20:52                           ` Guenter Roeck
2024-08-08 21:50                             ` John David Anglin
2024-08-08 22:29                               ` John David Anglin
2024-08-08 23:33                                 ` Linus Torvalds
2024-08-09  0:33                                   ` John David Anglin
2024-08-09  0:56                                 ` Guenter Roeck
2024-08-09  0:50                               ` Guenter Roeck
2024-08-08 22:15                             ` Richard Henderson
2024-09-03  7:54                           ` Helge Deller
2024-09-03 14:13                             ` Guenter Roeck
2024-09-03 18:43                             ` Linus Torvalds
     [not found]                 ` <cffe30ed-43a3-46ac-ad03-afb7633f17e5@roeck-us.net>
2024-08-08 15:58                   ` John David Anglin
     [not found]       ` <f63c6789-b01a-4d76-b7c9-74c04867bc13@roeck-us.net>
     [not found]         ` <CAHk-=wjmumbT73xLkSAnnxDwaFE__Ny=QCp6B_LE2aG1SUqiTg@mail.gmail.com>
2024-08-06 17:49           ` Linus Torvalds

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