From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD438C43461 for ; Tue, 18 May 2021 10:26:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A80F661002 for ; Tue, 18 May 2021 10:26:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348467AbhERK1Z (ORCPT ); Tue, 18 May 2021 06:27:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:35064 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239674AbhERK1X (ORCPT ); Tue, 18 May 2021 06:27:23 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 33B04AF19; Tue, 18 May 2021 10:26:04 +0000 (UTC) Subject: Re: [PATCH v10 19/33] mm/filemap: Add folio_lock To: "Matthew Wilcox (Oracle)" , akpm@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Hellwig , Jeff Layton References: <20210511214735.1836149-1-willy@infradead.org> <20210511214735.1836149-20-willy@infradead.org> From: Vlastimil Babka Message-ID: Date: Tue, 18 May 2021 12:26:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210511214735.1836149-20-willy@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/11/21 11:47 PM, Matthew Wilcox (Oracle) wrote: > This is like lock_page() but for use by callers who know they have a folio. > Convert __lock_page() to be __folio_lock(). This saves one call to > compound_head() per contended call to lock_page(). > > Saves 362 bytes of text; mostly from improved register allocation and > inlining decisions. __folio_lock is 59 bytes while __lock_page was 79. > > Signed-off-by: Matthew Wilcox (Oracle) > Reviewed-by: Christoph Hellwig > Acked-by: Jeff Layton Acked-by: Vlastimil Babka > --- > include/linux/pagemap.h | 24 +++++++++++++++++++----- > mm/filemap.c | 29 +++++++++++++++-------------- > 2 files changed, 34 insertions(+), 19 deletions(-) > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index 8dbba0074536..9a78397609b8 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -638,7 +638,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page, > return true; > } > > -extern void __lock_page(struct page *page); > +void __folio_lock(struct folio *folio); > 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, > @@ -646,13 +646,24 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, > void unlock_page(struct page *page); > void folio_unlock(struct folio *folio); > > +static inline bool folio_trylock(struct folio *folio) > +{ > + return likely(!test_and_set_bit_lock(PG_locked, folio_flags(folio, 0))); > +} > + > /* > * Return true if the page was successfully locked > */ > static inline int trylock_page(struct page *page) > { > - page = compound_head(page); > - return (likely(!test_and_set_bit_lock(PG_locked, &page->flags))); > + return folio_trylock(page_folio(page)); > +} > + > +static inline void folio_lock(struct folio *folio) > +{ > + might_sleep(); > + if (!folio_trylock(folio)) > + __folio_lock(folio); > } > > /* > @@ -660,9 +671,12 @@ static inline int trylock_page(struct page *page) > */ > static inline void lock_page(struct page *page) > { > + struct folio *folio; > might_sleep(); > - if (!trylock_page(page)) > - __lock_page(page); > + > + folio = page_folio(page); > + if (!folio_trylock(folio)) > + __folio_lock(folio); > } > > /* > diff --git a/mm/filemap.c b/mm/filemap.c > index e7a6a58d6cd9..c6e5ba176764 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -1187,7 +1187,7 @@ static void wake_up_page(struct page *page, int bit) > */ > enum behavior { > EXCLUSIVE, /* Hold ref to page and take the bit when woken, like > - * __lock_page() waiting on then setting PG_locked. > + * __folio_lock() waiting on then setting PG_locked. > */ > SHARED, /* Hold ref to page and check the bit when woken, like > * wait_on_page_writeback() waiting on PG_writeback. > @@ -1576,17 +1576,16 @@ void page_endio(struct page *page, bool is_write, int err) > EXPORT_SYMBOL_GPL(page_endio); > > /** > - * __lock_page - get a lock on the page, assuming we need to sleep to get it > - * @__page: the page to lock > + * __folio_lock - Get a lock on the folio, assuming we need to sleep to get it. > + * @folio: The folio to lock > */ > -void __lock_page(struct page *__page) > +void __folio_lock(struct folio *folio) > { > - struct page *page = compound_head(__page); > - wait_queue_head_t *q = page_waitqueue(page); > - wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE, > + wait_queue_head_t *q = page_waitqueue(&folio->page); > + wait_on_page_bit_common(q, &folio->page, PG_locked, TASK_UNINTERRUPTIBLE, > EXCLUSIVE); > } > -EXPORT_SYMBOL(__lock_page); > +EXPORT_SYMBOL(__folio_lock); > > int __lock_page_killable(struct page *__page) > { > @@ -1661,10 +1660,10 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm, > return 0; > } > } else { > - __lock_page(page); > + __folio_lock(page_folio(page)); > } > - return 1; > > + return 1; > } > > /** > @@ -2835,7 +2834,9 @@ loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start, > static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page, > struct file **fpin) > { > - if (trylock_page(page)) > + struct folio *folio = page_folio(page); > + > + if (folio_trylock(folio)) > return 1; > > /* > @@ -2848,7 +2849,7 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page, > > *fpin = maybe_unlock_mmap_for_io(vmf, *fpin); > if (vmf->flags & FAULT_FLAG_KILLABLE) { > - if (__lock_page_killable(page)) { > + if (__lock_page_killable(&folio->page)) { > /* > * We didn't have the right flags to drop the mmap_lock, > * but all fault_handlers only check for fatal signals > @@ -2860,11 +2861,11 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page, > return 0; > } > } else > - __lock_page(page); > + __folio_lock(folio); > + > return 1; > } > > - > /* > * Synchronous readahead happens when we don't even find a page in the page > * cache at all. We don't want to perform IO under the mmap sem, so if we have >