linux-kernel - Re: [PATCH v7 06/12] khugepaged: introduce khugepaged_scan

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: <9c54397f-3cbf-4fa2-bf69-ba89613d355f@linux.alibaba.com>
Date: Fri, 16 May 2025 11:20:42 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Nico Pache <npache@...hat.com>, linux-mm@...ck.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org
Cc: david@...hat.com, ziy@...dia.com, lorenzo.stoakes@...cle.com,
 Liam.Howlett@...cle.com, ryan.roberts@....com, dev.jain@....com,
 corbet@....net, rostedt@...dmis.org, mhiramat@...nel.org,
 mathieu.desnoyers@...icios.com, akpm@...ux-foundation.org,
 baohua@...nel.org, willy@...radead.org, peterx@...hat.com,
 wangkefeng.wang@...wei.com, usamaarif642@...il.com, sunnanyong@...wei.com,
 vishal.moola@...il.com, thomas.hellstrom@...ux.intel.com,
 yang@...amperecomputing.com, kirill.shutemov@...ux.intel.com,
 aarcange@...hat.com, raquini@...hat.com, anshuman.khandual@....com,
 catalin.marinas@....com, tiwai@...e.de, will@...nel.org,
 dave.hansen@...ux.intel.com, jack@...e.cz, cl@...two.org,
 jglisse@...gle.com, surenb@...gle.com, zokeefe@...gle.com,
 hannes@...xchg.org, rientjes@...gle.com, mhocko@...e.com,
 rdunlap@...radead.org
Subject: Re: [PATCH v7 06/12] khugepaged: introduce khugepaged_scan_bitmap for
 mTHP support



On 2025/5/15 11:22, Nico Pache wrote:
> khugepaged scans anons PMD ranges for potential collapse to a hugepage.
> To add mTHP support we use this scan to instead record chunks of utilized
> sections of the PMD.
> 
> khugepaged_scan_bitmap uses a stack struct to recursively scan a bitmap
> that represents chunks of utilized regions. We can then determine what
> mTHP size fits best and in the following patch, we set this bitmap while
> scanning the anon PMD. A minimum collapse order of 2 is used as this is
> the lowest order supported by anon memory.
> 
> max_ptes_none is used as a scale to determine how "full" an order must
> be before being considered for collapse.
> 
> When attempting to collapse an order that has its order set to "always"
> lets always collapse to that order in a greedy manner without
> considering the number of bits set.
> 
> Signed-off-by: Nico Pache <npache@...hat.com>

Sigh. You still haven't addressed or explained the issues I previously 
raised [1], so I don't know how to review this patch again...

[1] 
https://lore.kernel.org/all/83a66442-b7c7-42e7-af4e-fd211d8ed6f8@linux.alibaba.com/