linux-kernel - Re: [RFC PATCH v0 2/2] mm: sched: Batch-migrate misplaced pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <23858e11-4f8f-4ff0-a27d-9b720351af70@linux.ibm.com>
Date: Fri, 23 May 2025 14:35:32 +0530
From: Donet Tom <donettom@...ux.ibm.com>
To: Bharata B Rao <bharata@....com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Cc: Jonathan.Cameron@...wei.com, dave.hansen@...el.com, gourry@...rry.net,
        hannes@...xchg.org, mgorman@...hsingularity.net, mingo@...hat.com,
        peterz@...radead.org, raghavendra.kt@....com, riel@...riel.com,
        rientjes@...gle.com, sj@...nel.org, weixugc@...gle.com,
        willy@...radead.org, ying.huang@...ux.alibaba.com, ziy@...dia.com,
        dave@...olabs.net, nifan.cxl@...il.com, joshua.hahnjy@...il.com,
        xuezhengchu@...wei.com, yiannis@...corp.com, akpm@...ux-foundation.org,
        david@...hat.com
Subject: Re: [RFC PATCH v0 2/2] mm: sched: Batch-migrate misplaced pages


On 5/22/25 10:09 AM, Bharata B Rao wrote:
> Hi Donet,
>
> On 21-May-25 11:55 PM, Donet Tom wrote:
>>
>>> +static void migrate_queued_pages(struct list_head *migrate_list)
>>> +{
>>> +    int cur_nid, nid;
>>> +    struct folio *folio, *tmp;
>>> +    LIST_HEAD(nid_list);
>>> +
>>> +    folio = list_entry(migrate_list, struct folio, lru);
>>> +    cur_nid = folio_last_cpupid(folio);
>>
>> Hi Bharatha,
>>
>> This is target node ID right?
>
> Correct.
>
>>
>>
>>> +
>>> +    list_for_each_entry_safe(folio, tmp, migrate_list, lru) {
>>> +        nid = folio_xchg_last_cpupid(folio, -1);
>>
>> Just one doubt: to get the last CPU ID (target node ID) here, 
>> folio_xchg_last_cpupid()
>>
>> is used, whereas earlier folio_last_cpupid() was used. Is there a 
>> specific reason for
>>
>> using different functions?
>
> This function iterates over the isolated folios looking for the same 
> target_nid so that all of them can be migrated at once to the given 
> target_nid. Hence the first call just reads the target_nid from 
> last_cpupid field to note which nid is of interest in the current 
> iteration and the next call actually reads target_nid and resets the 
> last_cpupid field.


Thank you, Bharata, for the clarification.

>
> Regards,
> Bharata.