linux-kernel - Re: [PATCH 0/5] mm/vma: make more mmap logic userland testable

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Message-ID: <20241206003054.cj767w67kydv3rms@master>
Date: Fri, 6 Dec 2024 00:30:54 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Wei Yang <richard.weiyang@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
	Eric Biederman <ebiederm@...ssion.com>, Kees Cook <kees@...nel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/5] mm/vma: make more mmap logic userland testable

On Thu, Dec 05, 2024 at 07:03:08AM +0000, Lorenzo Stoakes wrote:
>On Wed, Dec 04, 2024 at 11:56:32PM +0000, Wei Yang wrote:
>> On Tue, Dec 03, 2024 at 06:05:07PM +0000, Lorenzo Stoakes wrote:
>> >This series carries on the work the work started in previous series and
>>                         ^^^      ^^^
>>
>> Duplicated?
>
>Thanks yes, but trivial enough that I'm not sure it's worth a
>correction. Will fix if need to respin.
>
>>
>> >continued in commit 52956b0d7fb9 ("mm: isolate mmap internal logic to
>> >mm/vma.c"), moving the remainder of memory mapping implementation details
>> >logic into mm/vma.c allowing the bulk of the mapping logic to be unit
>> >tested.
>> >
>> >It is highly useful to do so, as this means we can both fundamentally test
>> >this core logic, and introduce regression tests to ensure any issues
>> >previously resolved do not recur.
>> >
>> >Vitally, this includes the do_brk_flags() function, meaning we have both
>> >core means of userland mapping memory now testable.
>> >
>> >Performance testing was performed after this change given the brk() system
>> >call's sensitivity to change, and no performance regression was observed.
>>
>> May I ask what performance test is done?
>
>mmtests brk1, brk2 (will-it-scale)

The one from here ?

https://github.com/gormanm/mmtests

>
>You'd not really expect an impact based on relocation of this code, but
>with brk it's always worth checking...
>

Yes, I am trying to know usually what perform test we would use.

>>
>>
>> --
>> Wei Yang
>> Help you, Help me

-- 
Wei Yang
Help you, Help me