linux-kernel - Re: [PATCH] mm: huge_memory: don't force huge page alignment on 32 bit

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Date: Fri, 26 Jan 2024 10:41:49 +0100
From: Jiri Slaby <jirislaby@...nel.org>
To: akpm@...ux-foundation.org
Cc: surenb@...gle.com, riel@...riel.com, willy@...radead.org, cl@...ux.com,
 yang@...amperecomputing.com, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, "Bernhard M. Wiedemann" <bwiedemann@...e.de>,
 Michal Hocko <mhocko@...e.com>, Yang Shi <shy828301@...il.com>
Subject: Re: [PATCH] mm: huge_memory: don't force huge page alignment on 32
 bit

On 26. 01. 24, 10:36, Jiri Slaby wrote:
>>> --- a/mm/huge_memory.c
>>> +++ b/mm/huge_memory.c
>>> @@ -37,6 +37,7 @@
>>>   #include <linux/page_owner.h>
>>>   #include <linux/sched/sysctl.h>
>>>   #include <linux/memory-tiers.h>
>>> +#include <linux/compat.h>
>>>   #include <asm/tlb.h>
>>>   #include <asm/pgalloc.h>
>>> @@ -811,6 +812,14 @@ static unsigned long 
>>> __thp_get_unmapped_area(struct file *filp,
>>>       loff_t off_align = round_up(off, size);
>>>       unsigned long len_pad, ret;
>>> +    /*
>>> +     * It doesn't make too much sense to froce huge page alignment on
>>> +     * 32 bit system or compat userspace due to the contrained virtual
>>> +     * address space and address entropy.
>>> +     */
> 
> FWIW,
> Bernhard noticed that "froce" and "contrained", could you fix that 
> before applying the patch?

No, you can't:

1) it was merged to mm-stable already, and
2) the comment is not in that version at all [1]

[1] https://lore.kernel.org/all/20240126075612.87780C433F1@smtp.kernel.org/

> thanks,

-- 
js
suse labs