Re: [PATCH 2/3] mm: page table check

[Pasha Tatashin]

On Sun, Nov 28, 2021 at 9:57 PM Fusion Future <qydwhotmail@xxxxxxxxx> wrote:
>
> On 2021/11/29 00:57, Pasha Tatashin wrote:
> > This commit by itself would not cause the freeze or BUG_ON(), but the
> > next commit which enables it on x86 arch might.
>
> Yes, you are right. At the commit
> "[1e67abff1820489435aad3fcf258708c21c283ef] x86: mm: add x86_64 support
> for page table check" my system starts to experience the freeze.
>
> I can now reproduce the freeze by following the steps below:
>
> 1. Open 20 YouTube video pages, and a YouTube Music page.
> 2. Play music in the background. (The step can be omitted)
> 3. Run `git clone
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git ln`

Thanks, I found a reliable way to reproduce this problem on my workstation:
reduce the amount of physical memory to 4G via memmap kernel
parameter,  and use a script that starts chrome browser with 20 tabs
each pointing to a youtube.com page.

I will send an update after root cause.

> git will never successfully clone the repo because the system will
> freeze during the operation.
>
> I also tried adding `page_table_check=off` to the boot option but still

I will add support for page_table_check=off even when
CONFIG_PAGE_TABLE_CHECK_ENFORCED is set

Thanks,
Pasha