linux-kernel - Re: 32-bit PTI with THP = userspace corruption

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Message-ID: <alpine.LRH.2.21.1808311005080.31140@math.ut.ee>
Date:   Fri, 31 Aug 2018 10:10:52 +0300 (EEST)
From:   Meelis Roos <mroos@...ux.ee>
To:     Joerg Roedel <jroedel@...e.de>
cc:     Linux Kernel list <linux-kernel@...r.kernel.org>,
        linux-mm@...ck.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: 32-bit PTI with THP = userspace corruption

> > I am seeing userland corruption and application crashes on multiple 
> > 32-bit machines with 4.19-rc1+git. The machines vary: PII, PIII, P4. 
> > They are all Intel. AMD Duron/Athlon/AthlonMP have been fine in my tests 
> > so far (may be configuration dependent).
> 
> 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?

PAE was not visible itself, but when I changed HIGHMEM_4G to 
HIGHMEM_64G, X86_PAE was also selected and the resutling kernel works.

Also, I verified that the olid proliants with 6G RAM already have 
HIGHMEM_64G set and they do not exhibit the problem either.

-- 
Meelis Roos (mroos@...ux.ee)