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From: David Hildenbrand <david@redhat.com>
To: Anatoly Pugachev <matorola@gmail.com>, hev <r@hev.cc>
Cc: Peter Xu <peterx@redhat.com>,
	Thorsten Leemhuis <regressions@leemhuis.info>,
	Sparc kernel list <sparclinux@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: Test case for "mm/thp: carry over dirty bit when thp splits on pmd"
Date: Wed, 16 Nov 2022 12:28:41 +0100	[thread overview]
Message-ID: <d814343b-2fc9-bb03-8378-b7ce6bc7373e@redhat.com> (raw)
In-Reply-To: <CADxRZqxqb7f_WhMh=jweZP+ynf_JwGd-0VwbYgp4P+T0-AXosw@mail.gmail.com>

On 16.11.22 11:45, Anatoly Pugachev wrote:
> On Wed, Nov 16, 2022 at 11:49 AM hev <r@hev.cc> wrote:
>>
>> Hello Peter,
>>
>> I see a random crash issue  on the LoongArch system, that is caused by
>> commit 0ccf7f1 ("mm/thp: carry over dirty bit when thp splits on
>> pmd").
>>
>> Now, the thing is already resolved. The root cause is arch's mkdirty
>> is set hardware writable bit in unconditional. That breaks
>> write-protect and then breaks COW.

Ehm, does this imply that

pte = maybe_mkwrite(pte_mkdirty(pte), vma);

will result in a writable PTE, even though the VMA does not include 
VM_WRITE?

That would be really broken.

-- 
Thanks,

David / dhildenb



  reply	other threads:[~2022-11-16 11:28 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAHirt9gr7oL87co3y1hCs3Ux4utzFP5oj6GFOFMZuJR2Vv8+rA@mail.gmail.com>
2022-11-16 10:45 ` Anatoly Pugachev
2022-11-16 11:28   ` David Hildenbrand [this message]
2022-11-16 16:25   ` Peter Xu
2022-11-17  2:29     ` hev
2022-11-17 18:28       ` Peter Xu
2022-11-19 14:06         ` hev
2022-11-21 19:57           ` David Hildenbrand
2022-11-25 11:15             ` hev
2022-11-25 11:17               ` David Hildenbrand
2022-11-25 11:35                 ` hev
2022-11-21 18:55   ` Peter Xu
2022-11-25 11:38     ` hev
2022-11-25 18:42       ` Peter Xu

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