From: Jan Kara <jack@suse.cz>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/2] mm: Use clear_bit_unlock_is_negative_byte for PageWriteback
Date: Thu, 26 Mar 2020 13:40:47 +0100 [thread overview]
Message-ID: <20200326124047.GA13756@quack2.suse.cz> (raw)
In-Reply-To: <20200326122429.20710-3-willy@infradead.org>
On Thu 26-03-20 05:24:29, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> By moving PG_writeback down into the low bits of the page flags, we can
> use clear_bit_unlock_is_negative_byte() for writeback as well as the
> lock bit. wake_up_page() then has no more callers. Given the other
> code being executed between the clear and the test, this is not going
> to be as dramatic a win as it was for PageLocked, but symmetry between
> the two is nice and lets us remove some code.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
The patch looks good to me. Just one nit:
> + VM_BUG_ON_PAGE(!PageWriteback(page), page);
> + if (__clear_page_writeback(page))
> + wake_up_page_bit(page, PG_writeback);
Since __clear_page_writeback() isn't really prepared for PageWriteback()
not being set, can we move the VM_BUG_ON_PAGE() there? Otherwise feel free
to add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2020-03-26 12:40 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-26 12:24 [PATCH 0/2] Make PageWriteback use the PageLocked optimisation Matthew Wilcox
2020-03-26 12:24 ` [PATCH 1/2] mm: Remove definition of clear_bit_unlock_is_negative_byte Matthew Wilcox
2020-04-16 12:45 ` Will Deacon
2020-04-16 14:31 ` Matthew Wilcox
2020-03-26 12:24 ` [PATCH 2/2] mm: Use clear_bit_unlock_is_negative_byte for PageWriteback Matthew Wilcox
2020-03-26 12:40 ` Jan Kara [this message]
2020-03-26 12:44 ` Matthew Wilcox
2020-03-27 10:46 ` William Kucharski
2020-03-26 17:11 ` Christoph Hellwig
2020-03-26 17:16 ` Matthew Wilcox
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