linux-kernel - Re: [PATCH v2] mm: allow deferred page init for vmemmap only

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 for Android: free password hash cracker in your pocket

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

Date:   Thu, 10 May 2018 14:30:39 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>
Cc:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, linux-mm@...ck.org,
        mgorman@...hsingularity.net, mingo@...nel.org,
        peterz@...radead.org, rostedt@...dmis.org, fengguang.wu@...el.com,
        dennisszhou@...il.com
Subject: Re: [PATCH v2] mm: allow deferred page init for vmemmap only

On Thu 10-05-18 07:53:56, Pavel Tatashin wrote:
[...]
> Here is a sample path, where translation is required, that occurs before
> mm_init():
> 
> start_kernel()
>  trap_init()
>   setup_cpu_entry_areas()
>    setup_cpu_entry_area(cpu)
>     get_cpu_gdt_paddr(cpu)
>      per_cpu_ptr_to_phys(addr)
>       pcpu_addr_to_page(addr)
>        virt_to_page(addr)
>         pfn_to_page(__pa(addr) >> PAGE_SHIFT)

Thanks that helped me to see the problem. On the other hand isn't this a
bit of an overkill? AFAICS this affects only NEED_PER_CPU_KM which is !SMP
and DEFERRED_STRUCT_PAGE_INIT makes only very limited sense on UP,
right?

Or do we have more such places?
-- 
Michal Hocko
SUSE Labs