From patchwork Wed Dec 6 20:44:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13482240 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="bgXELJ87" Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DCE5135 for ; Wed, 6 Dec 2023 12:44:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:In-Reply-To:References; bh=rhWeIRptRNUgjmaD/wW4RujIHeTM8TT1pwDCRhhFjIs=; b=bgXELJ87R3tP8ilGHXJDckrMyc um7q6N8PUmF7+nj38xs/U4N332ER8dXBJGjswS+mIChgL+rP4iCibhzI2q0FEbK0xu/jwMCDrtbra /LVKpOBFkKdya3/YhSODZ1JRdOv9ge3bi2FjsDUupFgnJlDRUSPisLCW7ZK7SQne3aPyNvXA8U+Nq cPLP62wTky1kQCUMXJfJR3PAdh71y4ajPM4HIe6SJEDg1W5xCIGtcUX8UrjpxWoayc6nR3xI6ANj+ vvusKz5/IZr4EdgA++fzjxVDID31xZJnl6zK24rDa5gqt+TbinRbOq/ea8i5VyOB2EEciPXLhbxkJ NZA+MTjg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rAylA-003EgZ-Ic; Wed, 06 Dec 2023 20:44:44 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Hugh Dickins , Viacheslav Dubeyko , "Kirill A. Shutemov" , Luis Chamberlain , Hannes Reinecke Subject: [PATCH] mm: Support order-1 folios in the page cache Date: Wed, 6 Dec 2023 20:44:42 +0000 Message-Id: <20231206204442.771430-1-willy@infradead.org> X-Mailer: git-send-email 2.37.1 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Folios of order 1 have no space to store the deferred list. This is not a problem for the page cache as file-backed folios are never placed on the deferred list. All we need to do is prevent the core MM from touching the deferred list for order 1 folios and remove the code which prevented us from allocating order 1 folios. Link: https://lore.kernel.org/linux-mm/90344ea7-4eec-47ee-5996-0c22f42d6a6a@google.com/ Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/huge_mm.h | 7 +++++-- mm/filemap.c | 2 -- mm/huge_memory.c | 23 ++++++++++++++++++----- mm/internal.h | 4 +--- mm/readahead.c | 8 ++------ 5 files changed, 26 insertions(+), 18 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index fa0350b0812a..7b59ff685da3 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -140,7 +140,7 @@ bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags, unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags); -void folio_prep_large_rmappable(struct folio *folio); +struct folio *folio_prep_large_rmappable(struct folio *folio); bool can_split_folio(struct folio *folio, int *pextra_pins); int split_huge_page_to_list(struct page *page, struct list_head *list); static inline int split_huge_page(struct page *page) @@ -280,7 +280,10 @@ static inline bool hugepage_vma_check(struct vm_area_struct *vma, return false; } -static inline void folio_prep_large_rmappable(struct folio *folio) {} +static inline struct folio *folio_prep_large_rmappable(struct folio *folio) +{ + return folio; +} #define transparent_hugepage_flags 0UL diff --git a/mm/filemap.c b/mm/filemap.c index 32eedf3afd45..61321e920e30 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1911,8 +1911,6 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, gfp_t alloc_gfp = gfp; err = -ENOMEM; - if (order == 1) - order = 0; if (order > 0) alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN; folio = filemap_alloc_folio(alloc_gfp, order); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4f542444a91f..0df68a318922 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -610,11 +610,15 @@ struct deferred_split *get_deferred_split_queue(struct folio *folio) } #endif -void folio_prep_large_rmappable(struct folio *folio) +struct folio *folio_prep_large_rmappable(struct folio *folio) { - VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio); - INIT_LIST_HEAD(&folio->_deferred_list); + if (!folio || !folio_test_large(folio)) + return folio; + if (folio_order(folio) > 1) + INIT_LIST_HEAD(&folio->_deferred_list); folio_set_large_rmappable(folio); + + return folio; } static inline bool is_transparent_hugepage(struct folio *folio) @@ -2760,7 +2764,8 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) /* Prevent deferred_split_scan() touching ->_refcount */ spin_lock(&ds_queue->split_queue_lock); if (folio_ref_freeze(folio, 1 + extra_pins)) { - if (!list_empty(&folio->_deferred_list)) { + if (folio_order(folio) > 1 && + !list_empty(&folio->_deferred_list)) { ds_queue->split_queue_len--; list_del(&folio->_deferred_list); } @@ -2811,6 +2816,9 @@ void folio_undo_large_rmappable(struct folio *folio) struct deferred_split *ds_queue; unsigned long flags; + if (folio_order(folio) <= 1) + return; + /* * At this point, there is no one trying to add the folio to * deferred_list. If folio is not in deferred_list, it's safe @@ -2836,7 +2844,12 @@ void deferred_split_folio(struct folio *folio) #endif unsigned long flags; - VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio); + /* + * Order 1 folios have no space for a deferred list, but we also + * won't waste much memory by not adding them to the deferred list. + */ + if (folio_order(folio) <= 1) + return; /* * The try_to_unmap() in page reclaim path might reach here too, diff --git a/mm/internal.h b/mm/internal.h index b61034bd50f5..11a9021614dd 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -419,9 +419,7 @@ static inline struct folio *page_rmappable_folio(struct page *page) { struct folio *folio = (struct folio *)page; - if (folio && folio_order(folio) > 1) - folio_prep_large_rmappable(folio); - return folio; + return folio_prep_large_rmappable(folio); } static inline void prep_compound_head(struct page *page, unsigned int order) diff --git a/mm/readahead.c b/mm/readahead.c index 6925e6959fd3..48cca8e8de17 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -513,14 +513,10 @@ void page_cache_ra_order(struct readahead_control *ractl, /* Align with smaller pages if needed */ if (index & ((1UL << order) - 1)) { order = __ffs(index); - if (order == 1) - order = 0; } /* Don't allocate pages past EOF */ - while (index + (1UL << order) - 1 > limit) { - if (--order == 1) - order = 0; - } + while (index + (1UL << order) - 1 > limit) + --order; err = ra_alloc_folio(ractl, index, mark, order, gfp); if (err) break;