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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD733C3DA4A for ; Mon, 19 Aug 2024 14:17:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 48F006B0085; Mon, 19 Aug 2024 10:17:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 417D36B0088; Mon, 19 Aug 2024 10:17:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 291F36B0089; Mon, 19 Aug 2024 10:17:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 021386B0085 for ; Mon, 19 Aug 2024 10:17:50 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 7327E812A7 for ; Mon, 19 Aug 2024 14:17:50 +0000 (UTC) X-FDA: 82469198700.27.A061791 Received: from mail-qk1-f174.google.com (mail-qk1-f174.google.com [209.85.222.174]) by imf15.hostedemail.com (Postfix) with ESMTP id 41172A000B for ; Mon, 19 Aug 2024 14:17:47 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=O5afodW6; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf15.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.222.174 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724077011; a=rsa-sha256; cv=none; b=U6q8pQsvwa4nHCMIW7SWtW5Beau/ATRmk72HkgMLcX9d1KzzLQYkalCNWLixB6T0KdOdGI t+3izCBVwspd4ia5mImoqactVbqXUuuPbKiDzSOWvN8804b+THIx/qNz74iwOdjlU/REGt rjasBDp0RiQySHMUKSUNapQBH0Bt7uk= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=O5afodW6; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf15.hostedemail.com: domain of usamaarif642@gmail.com designates 209.85.222.174 as permitted sender) smtp.mailfrom=usamaarif642@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1724077011; 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-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=kd+OCc/I7wl1HmFL+34jOl78XXC4PYQH1gu0dcrr8Jo=; b=MDYhV1CPptjdfrhaxdiNy6UBdTC6r/jbCYVt96sCCB6WdAYOKb4SGyZQhC1oAu+zEODe+i wonVUF/4r9xmDhSq7RzLELCTdeRn13AACDtszeAiwA7O420Jkd76zhP052nkuyq83dhRcF TzdA+s9KfVCFakVwiS22bPIjAKabiiY= Received: by mail-qk1-f174.google.com with SMTP id af79cd13be357-7a3375015f8so309003685a.1 for ; Mon, 19 Aug 2024 07:17:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1724077067; x=1724681867; darn=kvack.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=kd+OCc/I7wl1HmFL+34jOl78XXC4PYQH1gu0dcrr8Jo=; b=O5afodW6vCMTBVk9BIsbNILXRBel3tFLVPHoFYwJClSOlF/9mPT1JvxnwMoBMdXI/C bjrOA5c7hhykzyOuaYZoDztvDwziqBR2ZJp7sNHeXfZaoJ5pDFqjtc7XjaanWluj5oVb PzQcpP9/baseA2zQ79VYFbPDOQws8L5nQkwNdtZIeKOjw7c5G5Z43nL8N3s1ojqPWzjT hWh6XnpCoJG0WyQJKAu3Ebk5iykXHyJTlmgkHgCSIYxMZo/PRVK/bIsTaqMOR/CR7eSr WrJbyXbow7D/5XZNLrq+FWCI0LzXTDNPQIxZapyv7CFN5XobysMxczQd6X/UqT/2x25k B0qA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724077067; x=1724681867; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=kd+OCc/I7wl1HmFL+34jOl78XXC4PYQH1gu0dcrr8Jo=; b=hGRK7K4XFKJqJajcBusINbXPQks/B5QWnU+lX8P0EcA6Jzstk+UMZUjfkRpGp0if0z dKDu67PotCUu1nZORn4Pd1GeNyn4ASiCmJ0XdqhPo9Ji5Hzv5SJJM3x/yrdHTcEwDnIw KEC19ge4NIHmkAImOPtZb6LRl0+64u1sQ/iD10spMm8LolJiXX6pY6kkrfjAGJEe23xO 57pne1pUq3G6w6cN1bav9C5R+OjpaseagO+zHBySFbuIQflEq28diHRil6oOpyIpHE+g aVB1WeKKo6402bB6MtvZJ9j8fc3V927hqMKs17qQN/Lyd4gi00yANoqSSE6c74HwItmZ PYPw== X-Forwarded-Encrypted: i=1; AJvYcCWq4aDy+BGUfzlI8sVIGblgVxYqVKnLgZLlhyB2SgdGlZ5WD0SwsFPAlx2zsWD66U/5MeaGOCFN6RO4Vj3R9UZkWLM= X-Gm-Message-State: AOJu0Yw6DSLVoYMen7vjkDyhYU4GB+21m49Fh7bLBwU9N0mi052LNRek Vy3wZKzs6fTlRO4qqKlE+i5+5T7DXH0H7AU3dJVf90BSuoDCVJUt X-Google-Smtp-Source: AGHT+IEt8YkNAPQ4jNaHTdOZyPZuQ9+drB4gPJbvF8jxmqUo42Y3ubJ1Y5C+DVxNg72pJgC42RC/xw== X-Received: by 2002:a05:620a:468a:b0:7a1:d9a1:b9b with SMTP id af79cd13be357-7a5069d8efcmr1380389685a.60.1724077066917; Mon, 19 Aug 2024 07:17:46 -0700 (PDT) Received: from ?IPV6:2a03:83e0:1145:4:1409:786c:cb1d:c3fb? ([2620:10d:c091:500::7:e1ca]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7a4ff0e5afesm435612785a.87.2024.08.19.07.17.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Aug 2024 07:17:46 -0700 (PDT) Message-ID: Date: Mon, 19 Aug 2024 10:17:45 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 4/6] mm: Introduce a pageflag for partially mapped folios To: Barry Song Cc: akpm@linux-foundation.org, linux-mm@kvack.org, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, roman.gushchin@linux.dev, yuzhao@google.com, david@redhat.com, ryan.roberts@arm.com, rppt@kernel.org, willy@infradead.org, cerasuolodomenico@gmail.com, ryncsn@gmail.com, corbet@lwn.net, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@meta.com References: <20240819023145.2415299-1-usamaarif642@gmail.com> <20240819023145.2415299-5-usamaarif642@gmail.com> Content-Language: en-US From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 41172A000B X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: txm8bpkg5znr7fs97t539c86jkxfujyy X-HE-Tag: 1724077067-8331 X-HE-Meta: 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 4Qan3u+m cPX84qxl6iuoqOnDkjyzeCkxm5VMYtc6/9SuZRaog9HpeV0lyQBwu7Z3TjqufXnW55t/IvdnJE9pRZ2VlIvYo2gfGexpKMRlkoZPovShHI7pImOyef+Yr2+gV0OzkpxyQwIMODnSu6mV+jqtxsB+LZu7Pd6Hk6W78eahrQlsYjGT9yJEPB5OsMVf0nwd6KIufL7iHsu7TDnCOuoyIUY/5Y1w50AXoXBq/skmDFAPN35xcyVIYYY6rFp4JnkZJewEjHcX8hAfKqZZvDDJDQj5Tk0w+WUYS5n1ijGG24ytpABGXsMLBR9SjsBK/uKBXBcuV10aM+ivsTqeDOTvnw91eKbxFkRk6/ep//Kyhwdf5oPlwl08/kEOu7mFWQL0qqMN5IywentIWDEBNSD5VnqX7YdUF/BVR/gabKNic/QTZHYdX12gh4N3+189puA== 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: On 19/08/2024 09:29, Barry Song wrote: > Hi Usama, > > I feel it is much better now! thanks! > > On Mon, Aug 19, 2024 at 2:31 PM Usama Arif wrote: >> >> Currently folio->_deferred_list is used to keep track of >> partially_mapped folios that are going to be split under memory >> pressure. In the next patch, all THPs that are faulted in and collapsed >> by khugepaged are also going to be tracked using _deferred_list. >> >> This patch introduces a pageflag to be able to distinguish between >> partially mapped folios and others in the deferred_list at split time in >> deferred_split_scan. Its needed as __folio_remove_rmap decrements >> _mapcount, _large_mapcount and _entire_mapcount, hence it won't be >> possible to distinguish between partially mapped folios and others in >> deferred_split_scan. >> >> Eventhough it introduces an extra flag to track if the folio is >> partially mapped, there is no functional change intended with this >> patch and the flag is not useful in this patch itself, it will >> become useful in the next patch when _deferred_list has non partially >> mapped folios. >> >> Signed-off-by: Usama Arif >> --- >> include/linux/huge_mm.h | 4 ++-- >> include/linux/page-flags.h | 11 +++++++++++ >> mm/huge_memory.c | 23 ++++++++++++++++------- >> mm/internal.h | 4 +++- >> mm/memcontrol.c | 3 ++- >> mm/migrate.c | 3 ++- >> mm/page_alloc.c | 5 +++-- >> mm/rmap.c | 5 +++-- >> mm/vmscan.c | 3 ++- >> 9 files changed, 44 insertions(+), 17 deletions(-) >> >> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h >> index 4c32058cacfe..969f11f360d2 100644 >> --- a/include/linux/huge_mm.h >> +++ b/include/linux/huge_mm.h >> @@ -321,7 +321,7 @@ static inline int split_huge_page(struct page *page) >> { >> return split_huge_page_to_list_to_order(page, NULL, 0); >> } >> -void deferred_split_folio(struct folio *folio); >> +void deferred_split_folio(struct folio *folio, bool partially_mapped); >> >> void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, >> unsigned long address, bool freeze, struct folio *folio); >> @@ -495,7 +495,7 @@ static inline int split_huge_page(struct page *page) >> { >> return 0; >> } >> -static inline void deferred_split_folio(struct folio *folio) {} >> +static inline void deferred_split_folio(struct folio *folio, bool partially_mapped) {} >> #define split_huge_pmd(__vma, __pmd, __address) \ >> do { } while (0) >> >> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h >> index a0a29bd092f8..c3bb0e0da581 100644 >> --- a/include/linux/page-flags.h >> +++ b/include/linux/page-flags.h >> @@ -182,6 +182,7 @@ enum pageflags { >> /* At least one page in this folio has the hwpoison flag set */ >> PG_has_hwpoisoned = PG_active, >> PG_large_rmappable = PG_workingset, /* anon or file-backed */ >> + PG_partially_mapped = PG_reclaim, /* was identified to be partially mapped */ >> }; >> >> #define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1) >> @@ -861,8 +862,18 @@ static inline void ClearPageCompound(struct page *page) >> ClearPageHead(page); >> } >> FOLIO_FLAG(large_rmappable, FOLIO_SECOND_PAGE) >> +FOLIO_TEST_FLAG(partially_mapped, FOLIO_SECOND_PAGE) >> +/* >> + * PG_partially_mapped is protected by deferred_split split_queue_lock, >> + * so its safe to use non-atomic set/clear. >> + */ >> +__FOLIO_SET_FLAG(partially_mapped, FOLIO_SECOND_PAGE) >> +__FOLIO_CLEAR_FLAG(partially_mapped, FOLIO_SECOND_PAGE) >> #else >> FOLIO_FLAG_FALSE(large_rmappable) >> +FOLIO_TEST_FLAG_FALSE(partially_mapped) >> +__FOLIO_SET_FLAG_NOOP(partially_mapped) >> +__FOLIO_CLEAR_FLAG_NOOP(partially_mapped) >> #endif >> >> #define PG_head_mask ((1UL << PG_head)) >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index 2d77b5d2291e..70ee49dfeaad 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -3398,6 +3398,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, >> * page_deferred_list. >> */ >> list_del_init(&folio->_deferred_list); >> + __folio_clear_partially_mapped(folio); >> } >> spin_unlock(&ds_queue->split_queue_lock); >> if (mapping) { >> @@ -3454,11 +3455,13 @@ void __folio_undo_large_rmappable(struct folio *folio) >> if (!list_empty(&folio->_deferred_list)) { >> ds_queue->split_queue_len--; >> list_del_init(&folio->_deferred_list); >> + __folio_clear_partially_mapped(folio); > > is it possible to make things clearer by > > if (folio_clear_partially_mapped) > __folio_clear_partially_mapped(folio); > > While writing without conditions isn't necessarily wrong, adding a condition > will improve the readability of the code and enhance the clarity of my mTHP > counters series. also help decrease smp cache sync if we can avoid > unnecessary writing? > Do you mean if(folio_test_partially_mapped(folio))? I don't like this idea. I think it makes the readability worse? If I was looking at if (test) -> clear for the first time, I would become confused why its being tested if its going to be clear at the end anyways? >> } >> spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); >> } >> >> -void deferred_split_folio(struct folio *folio) >> +/* partially_mapped=false won't clear PG_partially_mapped folio flag */ >> +void deferred_split_folio(struct folio *folio, bool partially_mapped) >> { >> struct deferred_split *ds_queue = get_deferred_split_queue(folio); >> #ifdef CONFIG_MEMCG >> @@ -3486,14 +3489,19 @@ void deferred_split_folio(struct folio *folio) >> if (folio_test_swapcache(folio)) >> return; >> >> - if (!list_empty(&folio->_deferred_list)) >> - return; >> - >> spin_lock_irqsave(&ds_queue->split_queue_lock, flags); >> + if (partially_mapped) { >> + if (!folio_test_partially_mapped(folio)) { >> + __folio_set_partially_mapped(folio); >> + if (folio_test_pmd_mappable(folio)) >> + count_vm_event(THP_DEFERRED_SPLIT_PAGE); >> + count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); >> + } >> + } else { >> + /* partially mapped folios cannot become non-partially mapped */ >> + VM_WARN_ON_FOLIO(folio_test_partially_mapped(folio), folio); >> + } >> if (list_empty(&folio->_deferred_list)) { >> - if (folio_test_pmd_mappable(folio)) >> - count_vm_event(THP_DEFERRED_SPLIT_PAGE); >> - count_mthp_stat(folio_order(folio), MTHP_STAT_SPLIT_DEFERRED); >> list_add_tail(&folio->_deferred_list, &ds_queue->split_queue); >> ds_queue->split_queue_len++; >> #ifdef CONFIG_MEMCG >> @@ -3542,6 +3550,7 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, >> } else { >> /* We lost race with folio_put() */ >> list_del_init(&folio->_deferred_list); >> + __folio_clear_partially_mapped(folio); > > as above? Do we also need if(test) for split_huge_page_to_list_to_order()? > >> ds_queue->split_queue_len--; >> } >> if (!--sc->nr_to_scan) >> diff --git a/mm/internal.h b/mm/internal.h >> index 52f7fc4e8ac3..27cbb5365841 100644 >> --- a/mm/internal.h >> +++ b/mm/internal.h >> @@ -662,8 +662,10 @@ static inline void prep_compound_head(struct page *page, unsigned int order) >> atomic_set(&folio->_entire_mapcount, -1); >> atomic_set(&folio->_nr_pages_mapped, 0); >> atomic_set(&folio->_pincount, 0); >> - if (order > 1) >> + if (order > 1) { >> INIT_LIST_HEAD(&folio->_deferred_list); >> + __folio_clear_partially_mapped(folio); > > if partially_mapped is true for a new folio, does it mean we already have > a bug somewhere? > > How is it possible for a new folio to be partially mapped? > Its not, I did it because I wanted to make it explicit that the folio is being initialized, similar to how before this INIT_LIST_HEAD(&folio->_deferred_list) is done here. There is no functional issue in removing it here, because I believe the flag is initialized to false from start. >> + } >> } >> >> static inline void prep_compound_tail(struct page *head, int tail_idx) >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index e1ffd2950393..0fd95daecf9a 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -4669,7 +4669,8 @@ static void uncharge_folio(struct folio *folio, struct uncharge_gather *ug) >> VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); >> VM_BUG_ON_FOLIO(folio_order(folio) > 1 && >> !folio_test_hugetlb(folio) && >> - !list_empty(&folio->_deferred_list), folio); >> + !list_empty(&folio->_deferred_list) && >> + folio_test_partially_mapped(folio), folio); >> >> /* >> * Nobody should be changing or seriously looking at >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 2d2e65d69427..ef4a732f22b1 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1735,7 +1735,8 @@ static int migrate_pages_batch(struct list_head *from, >> * use _deferred_list. >> */ >> if (nr_pages > 2 && >> - !list_empty(&folio->_deferred_list)) { >> + !list_empty(&folio->_deferred_list) && >> + folio_test_partially_mapped(folio)) { >> if (!try_split_folio(folio, split_folios, mode)) { >> nr_failed++; >> stats->nr_thp_failed += is_thp; >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 408ef3d25cf5..a145c550dd2a 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -957,8 +957,9 @@ static int free_tail_page_prepare(struct page *head_page, struct page *page) >> break; >> case 2: >> /* the second tail page: deferred_list overlaps ->mapping */ >> - if (unlikely(!list_empty(&folio->_deferred_list))) { >> - bad_page(page, "on deferred list"); >> + if (unlikely(!list_empty(&folio->_deferred_list) && >> + folio_test_partially_mapped(folio))) { >> + bad_page(page, "partially mapped folio on deferred list"); >> goto out; >> } >> break; >> diff --git a/mm/rmap.c b/mm/rmap.c >> index a6b9cd0b2b18..4c330635aa4e 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1578,8 +1578,9 @@ static __always_inline void __folio_remove_rmap(struct folio *folio, >> * Check partially_mapped first to ensure it is a large folio. >> */ >> if (partially_mapped && folio_test_anon(folio) && >> - list_empty(&folio->_deferred_list)) >> - deferred_split_folio(folio); >> + !folio_test_partially_mapped(folio)) >> + deferred_split_folio(folio, true); >> + >> __folio_mod_stat(folio, -nr, -nr_pmdmapped); >> >> /* >> diff --git a/mm/vmscan.c b/mm/vmscan.c >> index 25e43bb3b574..25f4e8403f41 100644 >> --- a/mm/vmscan.c >> +++ b/mm/vmscan.c >> @@ -1233,7 +1233,8 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, >> * Split partially mapped folios right away. >> * We can free the unmapped pages without IO. >> */ >> - if (data_race(!list_empty(&folio->_deferred_list)) && >> + if (data_race(!list_empty(&folio->_deferred_list) && >> + folio_test_partially_mapped(folio)) && >> split_folio_to_list(folio, folio_list)) >> goto activate_locked; >> } >> -- >> 2.43.5 >> > > Thanks > Barry