linux-kernel - RE: [PATCH v3 1/2] mm: migration: fix the FOLL

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: <BYAPR11MB34951FC5879F86F0183C8608F7689@BYAPR11MB3495.namprd11.prod.outlook.com>
Date:   Mon, 15 Aug 2022 02:10:59 +0000
From:   "Wang, Haiyue" <haiyue.wang@...el.com>
To:     "Huang, Ying" <ying.huang@...el.com>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "david@...hat.com" <david@...hat.com>,
        "linmiaohe@...wei.com" <linmiaohe@...wei.com>,
        "songmuchun@...edance.com" <songmuchun@...edance.com>,
        "naoya.horiguchi@...ux.dev" <naoya.horiguchi@...ux.dev>,
        "alex.sierra@....com" <alex.sierra@....com>
Subject: RE: [PATCH v3 1/2] mm: migration: fix the FOLL_GET failure on
 following huge page

> -----Original Message-----
> From: Huang, Ying <ying.huang@...el.com>
> Sent: Monday, August 15, 2022 09:59
> To: Wang, Haiyue <haiyue.wang@...el.com>
> Cc: linux-mm@...ck.org; linux-kernel@...r.kernel.org; akpm@...ux-foundation.org; david@...hat.com;
> linmiaohe@...wei.com; songmuchun@...edance.com; naoya.horiguchi@...ux.dev; alex.sierra@....com
> Subject: Re: [PATCH v3 1/2] mm: migration: fix the FOLL_GET failure on following huge page
> 
> Haiyue Wang <haiyue.wang@...el.com> writes:
> 
> > Not all huge page APIs support FOLL_GET option, so the __NR_move_pages
> 
> move_pages() is a syscall, so you can just call it move_pages(), or
> move_pages() syscall.

The application meets the issue, use the bellow function:
syscall (__NR_move_pages, 0, n_pages, ptr, 0, status, 0)

So I used it directly in the commit. "move_pages() syscall" is better.
Will update latter.

> 
> > will fail to get the page node information for huge page.
>                                                  ~~~~~~~~~
> some huge pages?

OK.

> 
> > This is an temporary solution to mitigate the racing fix.
> 
> Why is it "racing fix"?  This isn't a race condition fix.

The 'Fixes' commit is about race condition fix.

How about " his is an temporary solution to mitigate the side effect
Of the race condition fix"

> 
> Best Regards,
> Huang, Ying
> 
> > After supporting follow huge page by FOLL_GET is done, this fix can be
> > reverted safely.
> >
> > Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array racing with memory offline")
> > Signed-off-by: Haiyue Wang <haiyue.wang@...el.com>
> 
> [snip]