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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 22/33] mm/filemap: Add __folio_lock_or_retry
Date: Tue, 18 May 2021 12:38:46 +0200	[thread overview]
Message-ID: <76184de4-4ab9-0f04-ab37-8637f4b22566@suse.cz> (raw)
In-Reply-To: <20210511214735.1836149-23-willy@infradead.org>

On 5/11/21 11:47 PM, Matthew Wilcox (Oracle) wrote:
> Convert __lock_page_or_retry() to __folio_lock_or_retry().  This actually
> saves 4 bytes in the only caller of lock_page_or_retry() (due to better
> register allocation) and saves the 20 byte cost of calling page_folio()
> in __folio_lock_or_retry() for a total saving of 24 bytes.
> 
> 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 |  9 ++++++---
>  mm/filemap.c            | 10 ++++------
>  mm/memory.c             |  8 ++++----
>  3 files changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 41224e4ca8cc..21e394964288 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -640,7 +640,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,
>  
>  void __folio_lock(struct folio *folio);
>  int __folio_lock_killable(struct folio *folio);
> -extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
> +int __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
>  				unsigned int flags);
>  void unlock_page(struct page *page);
>  void folio_unlock(struct folio *folio);
> @@ -701,13 +701,16 @@ static inline int lock_page_killable(struct page *page)
>   * caller indicated that it can handle a retry.
>   *
>   * Return value and mmap_lock implications depend on flags; see
> - * __lock_page_or_retry().
> + * __folio_lock_or_retry().
>   */
>  static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
>  				     unsigned int flags)
>  {
> +	struct folio *folio;
>  	might_sleep();
> -	return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
> +
> +	folio = page_folio(page);
> +	return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
>  }
>  
>  /*
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 67334eb3fd94..28bf50041671 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1623,20 +1623,18 @@ static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait)
>  
>  /*
>   * Return values:
> - * 1 - page is locked; mmap_lock is still held.
> - * 0 - page is not locked.
> + * 1 - folio is locked; mmap_lock is still held.
> + * 0 - folio is not locked.
>   *     mmap_lock has been released (mmap_read_unlock(), unless flags had both
>   *     FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
>   *     which case mmap_lock is still held.
>   *
>   * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
> - * with the page locked and the mmap_lock unperturbed.
> + * with the folio locked and the mmap_lock unperturbed.
>   */
> -int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
> +int __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
>  			 unsigned int flags)
>  {
> -	struct folio *folio = page_folio(page);
> -
>  	if (fault_flag_allow_retry_first(flags)) {
>  		/*
>  		 * CAUTION! In this case, mmap_lock is not released

A bit later in this branch, 'page' is accessed, but it no longer exists. And
thus as expected, it doesn't compile. Assuming it's fixed later, but
bisectability etc...

> diff --git a/mm/memory.c b/mm/memory.c
> index 86ba6c1f6821..fc3f50d0702c 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -4065,7 +4065,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
>   * We enter with non-exclusive mmap_lock (to exclude vma changes,
>   * but allow concurrent faults).
>   * The mmap_lock may have been released depending on flags and our
> - * return value.  See filemap_fault() and __lock_page_or_retry().
> + * return value.  See filemap_fault() and __folio_lock_or_retry().
>   * If mmap_lock is released, vma may become invalid (for example
>   * by other thread calling munmap()).
>   */
> @@ -4307,7 +4307,7 @@ static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
>   * concurrent faults).
>   *
>   * The mmap_lock may have been released depending on flags and our return value.
> - * See filemap_fault() and __lock_page_or_retry().
> + * See filemap_fault() and __folio_lock_or_retry().
>   */
>  static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
>  {
> @@ -4411,7 +4411,7 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
>   * By the time we get here, we already hold the mm semaphore
>   *
>   * The mmap_lock may have been released depending on flags and our
> - * return value.  See filemap_fault() and __lock_page_or_retry().
> + * return value.  See filemap_fault() and __folio_lock_or_retry().
>   */
>  static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
>  		unsigned long address, unsigned int flags)
> @@ -4567,7 +4567,7 @@ static inline void mm_account_fault(struct pt_regs *regs,
>   * By the time we get here, we already hold the mm semaphore
>   *
>   * The mmap_lock may have been released depending on flags and our
> - * return value.  See filemap_fault() and __lock_page_or_retry().
> + * return value.  See filemap_fault() and __folio_lock_or_retry().
>   */
>  vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
>  			   unsigned int flags, struct pt_regs *regs)
> 


  reply	other threads:[~2021-05-18 10:38 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
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 [this message]
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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