linux-kernel - Re: [PATCH -v2 0/9] migrate

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Message-ID: <Y79tTXgEeuzzqFho@monkey>
Date:   Wed, 11 Jan 2023 18:15:41 -0800
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     "Huang, Ying" <ying.huang@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Zi Yan <ziy@...dia.com>,
        Yang Shi <shy828301@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Oscar Salvador <osalvador@...e.de>,
        Matthew Wilcox <willy@...radead.org>,
        Bharata B Rao <bharata@....com>,
        Alistair Popple <apopple@...dia.com>,
        haoxin <xhao@...ux.alibaba.com>
Subject: Re: [PATCH -v2 0/9] migrate_pages(): batch TLB flushing

On 01/12/23 08:09, Huang, Ying wrote:
> Hi, Mike,
> 
> Mike Kravetz <mike.kravetz@...cle.com> writes:
> 
> > On 01/10/23 17:53, Mike Kravetz wrote:
> >> Just saw the following easily reproducible issue on next-20230110.  Have not
> >> verified it is related to/caused by this series, but it looks suspicious.
> >
> > Verified this is caused by the series,
> >
> > 734cbddcfe72 migrate_pages: organize stats with struct migrate_pages_stats
> > to
> > 323b933ba062 migrate_pages: batch flushing TLB
> >
> > in linux-next.
> 
> Thanks for reporting.
> 
> I tried this yesterday (next-20230111), but failed to reproduce it.  Can
> you share your kernel config?  Is there any other setup needed?

Config file is attached.

Are you writing a REALLY big value to nr_hugepages?  By REALLY big I
mean a value that is impossible to fulfill.  This will result in
successful hugetlb allocations until __alloc_pages starts to fail.  At
this point we will be stressing compaction/migration trying to find more
contiguous pages.

Not sure if it matters, but I am running on a 2 node VM.  The 2 nodes
may be important as the hugetlb allocation code will try a little harder
alternating between nodes that may perhaps stress compaction/migration
more.

> BTW: can you bisect to one specific commit which causes the bug in the
> series?

I should have some time to isolate in the next day or so.
-- 
Mike Kravetz

View attachment ".config" of type "text/plain" (156584 bytes)