linux-kernel - Re: [PATCH v7 09/28] mm: Create FolioFlags

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Message-ID: <YH2E2jNvhEOwCinT@hirez.programming.kicks-ass.net>
Date:   Mon, 19 Apr 2021 15:25:46 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-cachefs@...hat.com,
        linux-afs@...ts.infradead.org, Christoph Hellwig <hch@....de>,
        Jeff Layton <jlayton@...nel.org>
Subject: Re: [PATCH v7 09/28] mm: Create FolioFlags

On Fri, Apr 09, 2021 at 07:50:46PM +0100, Matthew Wilcox (Oracle) wrote:
> These new functions are the folio analogues of the PageFlags functions.
> If CONFIG_DEBUG_VM_PGFLAGS is enabled, we check the folio is not a tail
> page at every invocation.  Note that this will also catch the PagePoisoned
> case as a poisoned page has every bit set, which would include PageTail.
> 
> This saves 1727 bytes of text with the distro-derived config that
> I'm testing due to removing a double call to compound_head() in
> PageSwapCache().

I vote for dropping the Camels if we're going to rework all this.