linux-kernel - Re: [PATCH] mm: remove offset check on page->compound

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Message-Id: <20220107160825.13c71fdd871d7d5611d116b9@linux-foundation.org>
Date:   Fri, 7 Jan 2022 16:08:25 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Wei Yang <richard.weiyang@...il.com>, peterz@...radead.org,
        vbabka@...e.cz, will@...nel.org, linyunsheng@...wei.com,
        aarcange@...hat.com, feng.tang@...el.com, ebiederm@...ssion.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: remove offset check on page->compound_head and
 folio->lru

On Fri, 7 Jan 2022 22:11:20 +0000 Matthew Wilcox <willy@...radead.org> wrote:

> On Fri, Jan 07, 2022 at 01:40:59PM +0000, Wei Yang wrote:
> > On Fri, Jan 07, 2022 at 03:59:01AM +0000, Matthew Wilcox wrote:
> > >On Thu, Jan 06, 2022 at 11:52:54PM +0000, Wei Yang wrote:
> > >> FOLIO_MATCH() is used to make sure struct page and folio has identical
> > >> layout for the first several words.
> > >> 
> > >> The comparison of offset between page->compound_head and folio->lru is
> > >> more like an internal check in struct page.
> > >> 
> > >> This patch just removes it.
> > >> 
> > >> Signed-off-by: Wei Yang <richard.weiyang@...il.com>
> > >
> > >No.
> > 
> > Hi, Matthew
> > 
> > Would you mind sharing some insight on this check?
> 
> It's right there in the comments.

Well I can't figure out which comment you're referring to?

> If you can't be bothered to read, why should I write?

I don't think the punishment comes close to fitting the crime here :(