linux-kernel - Re: linux-next: manual merge of the slab tree with the mm-unstable tree

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] [day] [month] [year] [list]

Message-ID: <4fe82763-09ec-4b3c-bfda-5997c55996a9@suse.cz>
Date: Tue, 22 Jul 2025 10:30:45 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Luiz Capitulino <luizcap@...hat.com>, Matthew Wilcox
 <willy@...radead.org>, Stephen Rothwell <sfr@...b.auug.org.au>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 Linux Next Mailing List <linux-next@...r.kernel.org>,
 David Hildenbrand <david@...hat.com>
Subject: Re: linux-next: manual merge of the slab tree with the mm-unstable
 tree

On 7/21/25 23:35, Luiz Capitulino wrote:
> On 2025-07-21 15:38, Matthew Wilcox wrote:
>> On Mon, Jul 21, 2025 at 02:20:01PM +1000, Stephen Rothwell wrote:
>>> Hi all,
>>>
>>> Today's linux-next merge of the slab tree got a conflict in:
>>>
>>>    fs/proc/page.c
>>>
>>> between commit:
>>>
>>>    a602ee331e31 ("fs: stable_page_flags(): use snapshot_page()")
>>>
>>> from the mm-unstable tree and commit:
>>>
>>>    d8178294c53e ("proc: Remove mention of PG_slab")
>>>
>>> from the slab tree.
>>>
>>> I fixed it up (I just used the former version) and can carry the fix as
>>> necessary. This is now fixed as far as linux-next is concerned, but any
>> 
>> I think the snapshot_page commit was incorrect in removing this comment.
>> It is still valuable information.  I think the comment from d8178294c53e
>> should remain in the tree after the resolution.
> 
> The comment wasn't just dropped, David suggested a new version for the comment
> (which is similar to yours). The new comment is now part of set_ps_flags()
> which is where we set this flag in the snapshot_page() implementation:
> 
> static void set_ps_flags(struct page_snapshot *ps, const struct folio *folio,
>                           const struct page *page)
> {
>          /*
>           * Only the first page of a high-order buddy page has PageBuddy() set.
>           * So we have to check manually whether this page is part of a high-
>           * order buddy page.
>           */
>          if (PageBuddy(page))
>                  ps->flags |= PAGE_SNAPSHOT_PG_BUDDY;

That seems to work. I can therefore simply drop d8178294c53e from the slab tree.

>          else if (page_count(page) == 0 && is_free_buddy_page(page))
>                  ps->flags |= PAGE_SNAPSHOT_PG_BUDDY;
> 
>          if (folio_test_idle(folio))
>                  ps->flags |= PAGE_SNAPSHOT_PG_IDLE;
> }
>