From: Vlastimil Babka <vbabka@suse.cz>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
akpm@linux-foundation.org
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Jeff Layton <jlayton@kernel.org>
Subject: Re: [PATCH v10 18/33] mm/filemap: Add folio_unlock
Date: Tue, 18 May 2021 12:06:42 +0200 [thread overview]
Message-ID: <e3869efd-b4a3-93a2-b510-21142db91603@suse.cz> (raw)
In-Reply-To: <20210511214735.1836149-19-willy@infradead.org>
On 5/11/21 11:47 PM, Matthew Wilcox (Oracle) wrote:
> Convert unlock_page() to call folio_unlock(). By using a folio we
> avoid a call to compound_head(). This shortens the function from 39
> bytes to 25 and removes 4 instructions on x86-64. Because we still
> have unlock_page(), it's a net increase of 24 bytes of text for the
> kernel as a whole, but any path that uses folio_unlock() will execute
> 4 fewer instructions.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Acked-by: Jeff Layton <jlayton@kernel.org>
> ---
> include/linux/pagemap.h | 3 ++-
> mm/filemap.c | 27 ++++++++++-----------------
> mm/folio-compat.c | 6 ++++++
> 3 files changed, 18 insertions(+), 18 deletions(-)
>
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 1f37d7656955..8dbba0074536 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -643,7 +643,8 @@ extern int __lock_page_killable(struct page *page);
> extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
> extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
> unsigned int flags);
> -extern void unlock_page(struct page *page);
> +void unlock_page(struct page *page);
> +void folio_unlock(struct folio *folio);
>
> /*
> * Return true if the page was successfully locked
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 817a47059bd0..e7a6a58d6cd9 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1435,29 +1435,22 @@ static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem
> #endif
>
> /**
> - * unlock_page - unlock a locked page
> - * @page: the page
> + * folio_unlock - Unlock a locked folio.
> + * @folio: The folio.
> *
> - * Unlocks the page and wakes up sleepers in wait_on_page_locked().
> - * Also wakes sleepers in wait_on_page_writeback() because the wakeup
> - * mechanism between PageLocked pages and PageWriteback pages is shared.
> - * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
> + * Unlocks the folio and wakes up any thread sleeping on the page lock.
> *
> - * Note that this depends on PG_waiters being the sign bit in the byte
> - * that contains PG_locked - thus the BUILD_BUG_ON(). That allows us to
> - * clear the PG_locked bit and test PG_waiters at the same time fairly
> - * portably (architectures that do LL/SC can test any bit, while x86 can
> - * test the sign bit).
Was it necessary to remove the comments about wait_on_page_writeback() and
PG_waiters etc?
> + * Context: May be called from interrupt or process context. May not be
> + * called from NMI context.
Where did the NMI part come from?
> */
> -void unlock_page(struct page *page)
> +void folio_unlock(struct folio *folio)
> {
> BUILD_BUG_ON(PG_waiters != 7);
> - page = compound_head(page);
> - VM_BUG_ON_PAGE(!PageLocked(page), page);
> - if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags))
> - wake_up_page_bit(page, PG_locked);
> + VM_BUG_ON_FOLIO(!folio_locked(folio), folio);
> + if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0)))
> + wake_up_page_bit(&folio->page, PG_locked);
> }
> -EXPORT_SYMBOL(unlock_page);
> +EXPORT_SYMBOL(folio_unlock);
>
> /**
> * end_page_private_2 - Clear PG_private_2 and release any waiters
> diff --git a/mm/folio-compat.c b/mm/folio-compat.c
> index 5e107aa30a62..91b3d00a92f7 100644
> --- a/mm/folio-compat.c
> +++ b/mm/folio-compat.c
> @@ -11,3 +11,9 @@ struct address_space *page_mapping(struct page *page)
> return folio_mapping(page_folio(page));
> }
> EXPORT_SYMBOL(page_mapping);
> +
> +void unlock_page(struct page *page)
> +{
> + return folio_unlock(page_folio(page));
> +}
> +EXPORT_SYMBOL(unlock_page);
>
next prev parent reply other threads:[~2021-05-18 10:06 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 21:47 [PATCH v10 00/33] Memory folios Matthew Wilcox (Oracle)
2021-05-11 21:47 ` [PATCH v10 01/33] mm: Introduce struct folio Matthew Wilcox (Oracle)
2021-05-14 10:34 ` Vlastimil Babka
2021-05-14 10:40 ` Vlastimil Babka
2021-05-14 11:47 ` Matthew Wilcox
2021-05-15 10:55 ` William Kucharski
2021-05-15 20:14 ` Matthew Wilcox
2021-05-16 19:26 ` William Kucharski
2021-05-27 8:09 ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 02/33] mm: Add folio_pgdat and folio_zone Matthew Wilcox (Oracle)
2021-05-14 10:35 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 03/33] mm/vmstat: Add functions to account folio statistics Matthew Wilcox (Oracle)
2021-05-14 10:36 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 04/33] mm/debug: Add VM_BUG_ON_FOLIO and VM_WARN_ON_ONCE_FOLIO Matthew Wilcox (Oracle)
2021-05-14 10:44 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 05/33] mm: Add folio reference count functions Matthew Wilcox (Oracle)
2021-05-14 11:04 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 06/33] mm: Add folio_put Matthew Wilcox (Oracle)
2021-05-14 11:52 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 07/33] mm: Add folio_get Matthew Wilcox (Oracle)
2021-05-14 11:56 ` Vlastimil Babka
2021-05-14 14:24 ` Matthew Wilcox
2021-05-14 15:39 ` Vlastimil Babka
2021-05-27 8:10 ` Christoph Hellwig
2021-05-27 22:53 ` Andrew Morton
2021-05-11 21:47 ` [PATCH v10 08/33] mm: Add folio_try_get_rcu Matthew Wilcox (Oracle)
2021-05-14 12:11 ` Vlastimil Babka
2021-05-27 8:16 ` Christoph Hellwig
2021-06-05 4:26 ` Matthew Wilcox
2021-06-06 14:13 ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 09/33] mm: Add folio flag manipulation functions Matthew Wilcox (Oracle)
2021-05-14 15:29 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 10/33] mm: Add folio_young and folio_idle Matthew Wilcox (Oracle)
2021-05-14 15:33 ` Vlastimil Babka
2021-05-27 8:17 ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 11/33] mm: Handle per-folio private data Matthew Wilcox (Oracle)
2021-05-14 15:41 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 12/33] mm/filemap: Add folio_index, folio_file_page and folio_contains Matthew Wilcox (Oracle)
2021-05-14 15:55 ` Vlastimil Babka
2021-05-15 15:51 ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 13/33] mm/filemap: Add folio_next_index Matthew Wilcox (Oracle)
2021-05-14 17:07 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 14/33] mm/filemap: Add folio_offset and folio_file_offset Matthew Wilcox (Oracle)
2021-05-14 17:08 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 15/33] mm/util: Add folio_mapping and folio_file_mapping Matthew Wilcox (Oracle)
2021-05-14 17:29 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 16/33] mm: Add folio_mapcount Matthew Wilcox (Oracle)
2021-05-14 17:39 ` Vlastimil Babka
2021-05-18 18:45 ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 17/33] mm/memcg: Add folio wrappers for various functions Matthew Wilcox (Oracle)
2021-05-18 9:57 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 18/33] mm/filemap: Add folio_unlock Matthew Wilcox (Oracle)
2021-05-18 10:06 ` Vlastimil Babka [this message]
2021-05-18 11:30 ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 19/33] mm/filemap: Add folio_lock Matthew Wilcox (Oracle)
2021-05-18 10:26 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 20/33] mm/filemap: Add folio_lock_killable Matthew Wilcox (Oracle)
2021-05-18 10:31 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 21/33] mm/filemap: Add __folio_lock_async Matthew Wilcox (Oracle)
2021-05-18 10:34 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 22/33] mm/filemap: Add __folio_lock_or_retry Matthew Wilcox (Oracle)
2021-05-18 10:38 ` Vlastimil Babka
2021-05-18 10:45 ` Vlastimil Babka
2021-05-18 13:35 ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 23/33] mm/filemap: Add folio_wait_locked Matthew Wilcox (Oracle)
2021-05-18 10:41 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 24/33] mm/swap: Add folio_rotate_reclaimable Matthew Wilcox (Oracle)
2021-05-18 10:48 ` Vlastimil Babka
2021-05-27 8:19 ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 25/33] mm/filemap: Add folio_end_writeback Matthew Wilcox (Oracle)
2021-05-18 11:08 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 26/33] mm/writeback: Add folio_wait_writeback Matthew Wilcox (Oracle)
2021-05-18 11:12 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 27/33] mm/writeback: Add folio_wait_stable Matthew Wilcox (Oracle)
2021-05-18 11:42 ` Vlastimil Babka
2021-05-18 13:55 ` Matthew Wilcox
2021-05-11 21:47 ` [PATCH v10 28/33] mm/filemap: Add folio_wait_bit Matthew Wilcox (Oracle)
2021-05-18 11:51 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 29/33] mm/filemap: Add folio_wake_bit Matthew Wilcox (Oracle)
2021-05-18 11:53 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 30/33] mm/filemap: Convert page wait queues to be folios Matthew Wilcox (Oracle)
2021-05-18 12:23 ` Vlastimil Babka
2021-05-11 21:47 ` [PATCH v10 31/33] mm/filemap: Add folio private_2 functions Matthew Wilcox (Oracle)
2021-05-18 12:26 ` Vlastimil Babka
2021-05-27 8:21 ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 32/33] fs/netfs: Add folio fscache functions Matthew Wilcox (Oracle)
2021-05-18 13:48 ` Vlastimil Babka
2021-05-27 8:23 ` Christoph Hellwig
2021-05-11 21:47 ` [PATCH v10 33/33] mm: Add folio_mapped Matthew Wilcox (Oracle)
2021-05-18 14:17 ` Vlastimil Babka
2021-05-27 8:31 ` Christoph Hellwig
2021-05-13 14:50 ` [PATCH v10 00/33] Memory folios Matthew Wilcox
2021-05-15 10:26 ` William Kucharski
2021-06-04 1:07 ` Matteo Croce
2021-06-04 2:13 ` Matthew Wilcox
2021-06-08 14:56 ` Matteo Croce
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