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Date:   Tue, 26 Apr 2022 17:08:01 -0400
From:   Qian Cai <quic_qiancai@quicinc.com>
To:     Zi Yan <ziy@nvidia.com>
CC:     David Hildenbrand <david@redhat.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>,
        <virtualization@lists.linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Mel Gorman <mgorman@techsingularity.net>,
        Eric Ren <renzhengeek@gmail.com>,
        Mike Rapoport <rppt@kernel.org>,
        "Oscar Salvador" <osalvador@suse.de>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v11 0/6] Use pageblock_order for cma and
 alloc_contig_range alignment.
Message-ID: <20220426210801.GA1038@qian>
References: <20220425143118.2850746-1-zi.yan@sent.com>
 <20220426201855.GA1014@qian>
 <B621B4DD-5D11-4F0E-AFF5-F8684AE37E57@nvidia.com>
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On Tue, Apr 26, 2022 at 04:26:08PM -0400, Zi Yan wrote:
> Thanks for reporting the issue. Do you have a reproducer I can use to debug the code?

Nothing fancy. It just try to remove and add back each memory section.

#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0

import os
import re
import subprocess


def mem_iter():
    base_dir = '/sys/devices/system/memory/'
    for curr_dir in os.listdir(base_dir):
        if re.match(r'memory\d+', curr_dir):
            yield base_dir + curr_dir


if __name__ == '__main__':
    print('- Try to remove each memory section and then add it back.')
    for mem_dir in mem_iter():
        status = f'{mem_dir}/online'
        if open(status).read().rstrip() == '1':
            # This could expectedly fail due to many reasons.
            section = os.path.basename(mem_dir)
            print(f'- Try to remove {section}.')
            proc = subprocess.run([f'echo 0 | sudo tee {status}'], shell=True)
            if proc.returncode == 0:
                print(f'- Try to add {section}.')
                subprocess.check_call([f'echo 1 | sudo tee {status}'], shell=True)