From patchwork Thu Jun 27 10:55:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Usama Arif X-Patchwork-Id: 13714184 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2255C30653 for ; Thu, 27 Jun 2024 10:57:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 58D7A6B00A4; Thu, 27 Jun 2024 06:57:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5130C6B00A3; Thu, 27 Jun 2024 06:57:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 366276B00A6; Thu, 27 Jun 2024 06:57:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 112CE6B00A3 for ; Thu, 27 Jun 2024 06:57:38 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id B09C9C111B for ; Thu, 27 Jun 2024 10:57:37 +0000 (UTC) X-FDA: 82276367754.24.01AB2C1 Received: from mail-qt1-f170.google.com (mail-qt1-f170.google.com [209.85.160.170]) by imf04.hostedemail.com (Postfix) with ESMTP id D919740009 for ; Thu, 27 Jun 2024 10:57:34 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=eaDk2xbO; spf=pass (imf04.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.160.170 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1719485838; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=TkzTW/11bPuGoCkFDaajiq8WxKpIkXClRk/0ynrGzvk=; b=RoQk7giUMm12A/kIMFQ1KN3fr3k+vp0Jsu3O+2jyCS5jXQ2qGQscnZn5zDNVIsifZtC0V6 SNTR0uz6lVBlZiuZOh9nQ1ONxk9wAqgov+FkhEpICSYguoHvOIT/f4nQpQmP/COKWxfI/X faAgdgjQhcT0jqAAVTu6uSzAS7jzkIE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1719485838; a=rsa-sha256; cv=none; b=SiK5PuBeH4QZosL1yP1Bu+vUhzlOVhvV80EX//ozZG0Ibh/fD0QEtZtsKWCOPZz10f9iUq xdBR4+jqFf89NYJwEGofyyv1VPYidH08B7UZrQLG99hi2gCzpIclIMRoiVdlbOGLRTs3cq 8yse+0kWRkjfl1/xxzXFnnkFgITd3fQ= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=eaDk2xbO; spf=pass (imf04.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.160.170 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com; dmarc=pass (policy=none) header.from=gmail.com Received: by mail-qt1-f170.google.com with SMTP id d75a77b69052e-44054a2c153so34753371cf.2 for ; Thu, 27 Jun 2024 03:57:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1719485854; x=1720090654; darn=kvack.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=TkzTW/11bPuGoCkFDaajiq8WxKpIkXClRk/0ynrGzvk=; b=eaDk2xbOZvcwcD4uDJ1tuDqSxTxQGPMVcs2nhPD6+S65mrgmRItATF7na7fLhbPICz I6p4O+5ymupJK8LmjuIQyrXFrp60Ny6ZMu8bFLFURjtPfD416Y2HYm807rrUqIQAeC1B 2w2fddXyQRSx/e+QWvKH6i/E2zIaD81mphrWxMlPwz63eUf2Ch6YcM5c/s0y6yxnzeik 7sHfRpvYrvovcN69PcOWF3AgU7uAzJH5fzYok0/QBonTaU+vMzRsW2P+RaxMIe/w1cQD yapRiWoDx7EzrK3Z4i4wMBppRMv1xX1sFdkTudehx3mucnvzYbAMBT++SBR28q4cph9r jllQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719485854; x=1720090654; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=TkzTW/11bPuGoCkFDaajiq8WxKpIkXClRk/0ynrGzvk=; b=bhlgvJ0bDtRokAOTxR16ddMu0HslKqimyGWF05bqfko027Rqz/wJ3GssJWWilyhwDi h8jfwSkpci16AmPXK0XxFUd1WG2dYlwntyvQmPzdBnFO9URH47Kg7N2yIm06244z8O8f GYdbdExK/TESzzADQTSAu5SSFQJPxiwuHjBlE0FUpXfIx8ML1u3SkoGR7NSNIqVkeuQO apaDNdwG+z3z8/LPyw/RDO0eIdvlNcU2jIG+nK+6x6zLT3YMfz+rhv1y+rINwZNq6ywR 9N130pUi13gmw1ZuUGhiXrJ1ua+jdnZghngSo5/3A7O8DI15C+tvd/Xve2Ilx7UF0ayk o3Ww== X-Forwarded-Encrypted: i=1; AJvYcCWsjtgNobTNOmP/MLdwWV1dg7xwzqHmmEd2i+AxMyiT88UJeXJpjd34IEgne4j70CHTeC75VQAg7IXqwMloedpqGgI= X-Gm-Message-State: AOJu0Yxum3dvL1ypAc+OV3bQQ/I84znl65//EPfr4gHBImILIX/RSdMj a7XOcAH4i2WGcdfBc+B9I2F0zi16TN0/QM1UfP6fHJSuK+ku3Vbo X-Google-Smtp-Source: AGHT+IG1BjfEOxsFo5R+ptwaWh5pstieIxvFw0KT+PkhQXtF7aARv9WfbDIto8OWrrisoVsji9V5dA== X-Received: by 2002:a05:622a:15d3:b0:445:5ae:ba84 with SMTP id d75a77b69052e-44505aec008mr64953341cf.15.1719485853832; Thu, 27 Jun 2024 03:57:33 -0700 (PDT) Received: from localhost (fwdproxy-ash-004.fbsv.net. [2a03:2880:20ff:4::face:b00c]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-44641eb4699sm4796381cf.38.2024.06.27.03.57.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Jun 2024 03:57:33 -0700 (PDT) From: Usama Arif To: akpm@linux-foundation.org Cc: hannes@cmpxchg.org, shakeel.butt@linux.dev, david@redhat.com, ying.huang@intel.com, hughd@google.com, willy@infradead.org, yosryahmed@google.com, nphamcs@gmail.com, chengming.zhou@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, Usama Arif , Andi Kleen Subject: [PATCH v7 1/2] mm: store zero pages to be swapped out in a bitmap Date: Thu, 27 Jun 2024 11:55:29 +0100 Message-ID: <20240627105730.3110705-2-usamaarif642@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240627105730.3110705-1-usamaarif642@gmail.com> References: <20240627105730.3110705-1-usamaarif642@gmail.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D919740009 X-Stat-Signature: 3ybtz5oqgireiaxe4t3by7bn4umo3ene X-HE-Tag: 1719485854-3112 X-HE-Meta: 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 2w2r5pr0 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Approximately 10-20% of pages to be swapped out are zero pages [1]. Rather than reading/writing these pages to flash resulting in increased I/O and flash wear, a bitmap can be used to mark these pages as zero at write time, and the pages can be filled at read time if the bit corresponding to the page is set. With this patch, NVMe writes in Meta server fleet decreased by almost 10% with conventional swap setup (zswap disabled). [1] https://lore.kernel.org/all/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1/ Signed-off-by: Usama Arif Reviewed-by: Chengming Zhou Reviewed-by: Yosry Ahmed Reviewed-by: Nhat Pham Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Shakeel Butt Cc: Usama Arif Cc: Andi Kleen Signed-off-by: Andrew Morton Acked-by: Johannes Weiner Signed-off-by: Usama Arif Reviewed-by: Chengming Zhou Reviewed-by: Yosry Ahmed Reviewed-by: Nhat Pham Signed-off-by: Andrew Morton Acked-by: Johannes Weiner Signed-off-by: Usama Arif Reviewed-by: Chengming Zhou Reviewed-by: Yosry Ahmed Reviewed-by: Nhat Pham Signed-off-by: Andrew Morton Acked-by: Johannes Weiner Signed-off-by: Usama Arif Reviewed-by: Chengming Zhou Reviewed-by: Yosry Ahmed Reviewed-by: Nhat Pham Signed-off-by: Andrew Morton Acked-by: Johannes Weiner --- include/linux/swap.h | 1 + mm/page_io.c | 113 ++++++++++++++++++++++++++++++++++++++++++- mm/swapfile.c | 20 ++++++++ 3 files changed, 133 insertions(+), 1 deletion(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 3df75d62a835..ed03d421febd 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -299,6 +299,7 @@ struct swap_info_struct { signed char type; /* strange name for an index */ unsigned int max; /* extent of the swap_map */ unsigned char *swap_map; /* vmalloc'ed array of usage counts */ + unsigned long *zeromap; /* vmalloc'ed bitmap to track zero pages */ struct swap_cluster_info *cluster_info; /* cluster info. Only for SSD */ struct swap_cluster_list free_clusters; /* free clusters list */ unsigned int lowest_bit; /* index of first free in swap_map */ diff --git a/mm/page_io.c b/mm/page_io.c index 6c1c1828bb88..480b8f221d90 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -172,6 +172,88 @@ int generic_swapfile_activate(struct swap_info_struct *sis, goto out; } +static bool is_folio_page_zero_filled(struct folio *folio, int i) +{ + unsigned long *data; + unsigned int pos, last_pos = PAGE_SIZE / sizeof(*data) - 1; + bool ret = false; + + data = kmap_local_folio(folio, i * PAGE_SIZE); + if (data[last_pos]) + goto out; + for (pos = 0; pos < PAGE_SIZE / sizeof(*data); pos++) { + if (data[pos]) + goto out; + } + ret = true; +out: + kunmap_local(data); + return ret; +} + +static bool is_folio_zero_filled(struct folio *folio) +{ + unsigned int i; + + for (i = 0; i < folio_nr_pages(folio); i++) { + if (!is_folio_page_zero_filled(folio, i)) + return false; + } + return true; +} + +static void folio_zero_fill(struct folio *folio) +{ + unsigned int i; + + for (i = 0; i < folio_nr_pages(folio); i++) + clear_highpage(folio_page(folio, i)); +} + +static void swap_zeromap_folio_set(struct folio *folio) +{ + struct swap_info_struct *sis = swp_swap_info(folio->swap); + swp_entry_t entry; + unsigned int i; + + for (i = 0; i < folio_nr_pages(folio); i++) { + entry = page_swap_entry(folio_page(folio, i)); + set_bit(swp_offset(entry), sis->zeromap); + } +} + +static void swap_zeromap_folio_clear(struct folio *folio) +{ + struct swap_info_struct *sis = swp_swap_info(folio->swap); + swp_entry_t entry; + unsigned int i; + + for (i = 0; i < folio_nr_pages(folio); i++) { + entry = page_swap_entry(folio_page(folio, i)); + clear_bit(swp_offset(entry), sis->zeromap); + } +} + +/* + * Return the index of the first subpage which is not zero-filled + * according to swap_info_struct->zeromap. + * If all pages are zero-filled according to zeromap, it will return + * folio_nr_pages(folio). + */ +static unsigned int swap_zeromap_folio_test(struct folio *folio) +{ + struct swap_info_struct *sis = swp_swap_info(folio->swap); + swp_entry_t entry; + unsigned int i; + + for (i = 0; i < folio_nr_pages(folio); i++) { + entry = page_swap_entry(folio_page(folio, i)); + if (!test_bit(swp_offset(entry), sis->zeromap)) + return i; + } + return i; +} + /* * We may have stale swap cache pages in memory: notice * them here and get rid of the unnecessary final write. @@ -195,6 +277,13 @@ int swap_writepage(struct page *page, struct writeback_control *wbc) folio_unlock(folio); return ret; } + + if (is_folio_zero_filled(folio)) { + swap_zeromap_folio_set(folio); + folio_unlock(folio); + return 0; + } + swap_zeromap_folio_clear(folio); if (zswap_store(folio)) { folio_unlock(folio); return 0; @@ -424,6 +513,26 @@ static void sio_read_complete(struct kiocb *iocb, long ret) mempool_free(sio, sio_pool); } +static bool swap_read_folio_zeromap(struct folio *folio) +{ + unsigned int idx = swap_zeromap_folio_test(folio); + + if (idx == 0) + return false; + + /* + * Swapping in a large folio that is partially in the zeromap is not + * currently handled. Return true without marking the folio uptodate so + * that an IO error is emitted (e.g. do_swap_page() will sigbus). + */ + if (WARN_ON_ONCE(idx < folio_nr_pages(folio))) + return true; + + folio_zero_fill(folio); + folio_mark_uptodate(folio); + return true; +} + static void swap_read_folio_fs(struct folio *folio, struct swap_iocb **plug) { struct swap_info_struct *sis = swp_swap_info(folio->swap); @@ -514,7 +623,9 @@ void swap_read_folio(struct folio *folio, struct swap_iocb **plug) } delayacct_swapin_start(); - if (zswap_load(folio)) { + if (swap_read_folio_zeromap(folio)) { + folio_unlock(folio); + } else if (zswap_load(folio)) { folio_unlock(folio); } else if (data_race(sis->flags & SWP_FS_OPS)) { swap_read_folio_fs(folio, plug); diff --git a/mm/swapfile.c b/mm/swapfile.c index 9c6d8e557c0f..028d33f3a76d 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -747,6 +747,14 @@ static void swap_range_free(struct swap_info_struct *si, unsigned long offset, unsigned long begin = offset; unsigned long end = offset + nr_entries - 1; void (*swap_slot_free_notify)(struct block_device *, unsigned long); + unsigned int i; + + /* + * Use atomic clear_bit operations only on zeromap instead of non-atomic + * bitmap_clear to prevent adjacent bits corruption due to simultaneous writes. + */ + for (i = 0; i < nr_entries; i++) + clear_bit(offset + i, si->zeromap); if (offset < si->lowest_bit) si->lowest_bit = offset; @@ -2635,6 +2643,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) free_percpu(p->cluster_next_cpu); p->cluster_next_cpu = NULL; vfree(swap_map); + kvfree(p->zeromap); kvfree(cluster_info); /* Destroy swap account information */ swap_cgroup_swapoff(p->type); @@ -3161,6 +3170,17 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) goto bad_swap_unlock_inode; } + /* + * Use kvmalloc_array instead of bitmap_zalloc as the allocation order might + * be above MAX_PAGE_ORDER incase of a large swap file. + */ + p->zeromap = kvmalloc_array(BITS_TO_LONGS(maxpages), sizeof(unsigned long), + GFP_KERNEL | __GFP_ZERO); + if (!p->zeromap) { + error = -ENOMEM; + goto bad_swap_unlock_inode; + } + if (p->bdev && bdev_stable_writes(p->bdev)) p->flags |= SWP_STABLE_WRITES;