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From: Joerg Roedel <jroedel@suse.de>
To: Meelis Roos <mroos@linux.ee>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>,
	linux-mm@kvack.org, Thomas Gleixner <tglx@linutronix.de>
Subject: Re: 32-bit PTI with THP = userspace corruption
Date: Fri, 31 Aug 2018 09:07:22 +0200	[thread overview]
Message-ID: <20180831070722.wnulbbmillxkw7ke@suse.de> (raw)
In-Reply-To: <alpine.LRH.2.21.1808310711380.17865@math.ut.ee>

On Fri, Aug 31, 2018 at 07:12:44AM +0300, Meelis Roos wrote:
> > Thanks for the report! I'll try to reproduce the problem tomorrow and
> > investigate it. Can you please check if any of the kernel configurations
> > that show the bug has CONFIG_X86_PAE set? If not, can you please test
> > if enabling this option still triggers the problem?
> 
> Will check, but out of my memery there were 2 G3 HP Proliants that did 
> not fit into the pattern (problem did not appear). I have more than 4G 
> RAM in those and HIGHMEM_4G there, maybe that's it?

Yeah, I thought a bit about it, and for legacy paging the PMD paging
level is the root-level where we do the mirroring between kernel and
user page-table for PTI. This means we also need to collect A/D bits
from both entries, which we don't do yet.

But that all means it shouldn't happen with CONFIG_X86_PAE=y.

I'll try to reproduce and work on a fix.

Thanks,

	Joerg

  reply	other threads:[~2018-08-31  7:07 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-30 18:09 32-bit PTI with THP = userspace corruption Meelis Roos
2018-08-30 20:55 ` Joerg Roedel
2018-08-31  4:12   ` Meelis Roos
2018-08-31  7:07     ` Joerg Roedel [this message]
2018-09-08 10:24       ` Thomas Gleixner
2018-09-11 11:49         ` Joerg Roedel
2018-09-11 11:58           ` Meelis Roos
2018-09-11 12:12             ` Joerg Roedel
2018-09-18 13:00               ` Alan Cox
2018-10-21 12:37                 ` Pavel Machek
2018-10-22  7:56                   ` Joerg Roedel
2018-10-22 18:48                     ` Alan Cox
2018-10-23  9:11                       ` Not-so-old machines without PAE was " Pavel Machek
2018-10-22 20:56                     ` Pavel Machek
2018-09-11 18:20           ` Linus Torvalds
2018-08-31  7:10   ` Meelis Roos

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