linux-kernel - Re: Re: [PATCH] mm: hugetlbfs: add hwcrp_hugepages to record memory failure on hugetlbfs

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Message-ID: <20210608091352.GA943097@hori.linux.bs1.fc.nec.co.jp>
Date:   Tue, 8 Jun 2021 09:13:52 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     wangbin <wangbin224@...wei.com>
CC:     "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "nao.horiguchi@...il.com" <nao.horiguchi@...il.com>,
        "wuxu.wu@...wei.com" <wuxu.wu@...wei.com>
Subject: Re: Re: [PATCH] mm: hugetlbfs: add hwcrp_hugepages to record memory
 failure on hugetlbfs

On Tue, Jun 08, 2021 at 10:24:50AM +0800, wangbin wrote:
> > What specific problem are you trying to solve?  Are trying to see how
> > many huge pages were hit by memory errors?
> 
> Yes, I'd like to know how many huge pages are not available because of
> the memory errors. Just like HardwareCorrupted in the /proc/meminfo.
> But the HardwareCorrupted only adds one page size when a huge page is
> hit by memory errors, and mixes with normal pages. So I think we should
> add a new counts to track the memory errors on hugetlbfs. 

If you can use root privilege in your use-case, an easy way to get the
number of corrupted hugepages is to use page-types.c (which reads
/proc/kpageflags) like below:

    $ page-types -b huge,hwpoison=huge,hwpoison
                 flags      page-count       MB  symbolic-flags                     long-symbolic-flags
    0x00000000000a8000               1        0  _______________H_G_X_______________________        compound_head,huge,hwpoison
                 total               1        0


But I guess that many usecases do not permit access to this interface,
where some new accounting interface for corrupted hugepages could be
helpful as you suggest.

Thanks,
Naoya Horiguchi