linux-kernel - Re: [PATCH v8 2/4] uprobe: use original page when all uprobes are removed

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: <4398BBD5-31AB-4342-9572-32763B016175@fb.com>
Date:   Fri, 26 Jul 2019 21:19:54 +0000
From:   Song Liu <songliubraving@...com>
To:     Oleg Nesterov <oleg@...hat.com>
CC:     lkml <linux-kernel@...r.kernel.org>, Linux-MM <linux-mm@...ck.org>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        "matthew.wilcox@...cle.com" <matthew.wilcox@...cle.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "Kernel Team" <Kernel-team@...com>,
        "william.kucharski@...cle.com" <william.kucharski@...cle.com>
Subject: Re: [PATCH v8 2/4] uprobe: use original page when all uprobes are
 removed



> On Jul 26, 2019, at 1:44 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> 
> On 07/25, Song Liu wrote:
>> 
>> I guess I know the case now. We can probably avoid this with an simp.le 
>> check for old_page == new_page?
> 
> better yet, I think we can check PageAnon(old_page) and avoid the unnecessary
> __replace_page() in this case. See the patch below.

I added PageAnon(old_page) check in v9 of the patch. 

> 
> Anyway, why __replace_page() needs to lock both pages? This doesn't look nice
> even if it were correct. I think it can do lock_page(old_page) later.
> 

Agreed. I have changed the v9 to only unmap old_page. So it should be cleaner. 

Thanks again for these good suggestions,
Song