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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A5013C352A1 for ; Tue, 6 Dec 2022 17:16:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235692AbiLFRQk (ORCPT ); Tue, 6 Dec 2022 12:16:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235639AbiLFRQj (ORCPT ); Tue, 6 Dec 2022 12:16:39 -0500 Received: from mail-wm1-x329.google.com (mail-wm1-x329.google.com [IPv6:2a00:1450:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E91B2F24 for ; Tue, 6 Dec 2022 09:16:37 -0800 (PST) Received: by mail-wm1-x329.google.com with SMTP id m19so11685079wms.5 for ; Tue, 06 Dec 2022 09:16:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:from:to:cc:subject:date:message-id :reply-to; bh=ubdJCuH5kFmnXLiRXBD1CLTzDkiF2pzms1SkFrWFmC4=; b=Sw0E4Qa1A2uyX+0QpmaCzix1jLcv9Oe2mZtlI7MvV0OhEdKhzd4Y9RzIGlfuuuNsda J6hiOKSClX30z61ntL1vGmri/tYRojvTVthg6nsgUPn1nnoUjpLYqeERJf4vzlQC4KV8 GzsjOoYYozGpJVZ+Sh2KkEgG+8xprR4/CwT/y7cwUhA7DIjaVCGJwseKO8UuPX0cgTiW AQRmplV1B868iViA8XU+nBKIRfcNDE58lyQuXVYTbyBejeHC0eaZqBFZrsKk97xd0n0d oUQMC6dNb+BfW0AZitfGzcuf3HVMpvJUBll36mA+AGblmxI2vkCXNjkqPacOBWIRysS3 kBpg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ubdJCuH5kFmnXLiRXBD1CLTzDkiF2pzms1SkFrWFmC4=; b=eEQZUsPZAed/oQnJdfskgDMJyYpaMImVSIuvZEpAvDZztIrLxdlhVlfSOTeKS3ju7F dq4TSlWM0Ak20+/608Jsue0r0PFP9QvhMFXxZKpCDRaDHIW25vKI7H+7HjEaTJAK/IxB 2LYqFKKvj8NckA1l2fqybKXwJBNNynwCMTHvsBUilmRs104uvZK/T3n5EdU71ObT03xI XodylGFBXtr6uN9V/bobMdSI1x407bNb8fY0ZVY1xHHNkdXHQYfbCi6llMbaRP7GIrUk Jg58EpEbrypEjZWukqQC4uWJmiRMQMTjjP8WYYSlz1lFw2DcJ3V7GJQ3IdQM7gBBwQXq H9Uw== X-Gm-Message-State: ANoB5pmfzxwKqOEEmM3SR47uGydwY2R4BufnmtxtscKk9JHsDZeP0/ZQ 0Yca5n23zCOAKTqTjLoiRTpWB/v2L+X2PR7K X-Google-Smtp-Source: AA0mqf6+LabElStuak0FhJ7uuwNuqHHptd9ZKT7FXNctSWt01qOBNU+M1lxqyZephUcypGn5BTQ0Dw== X-Received: by 2002:a1c:740d:0:b0:3d1:ed5f:b8f2 with SMTP id p13-20020a1c740d000000b003d1ed5fb8f2mr2519261wmc.24.1670346996465; Tue, 06 Dec 2022 09:16:36 -0800 (PST) Received: from localhost ([2a00:79e0:9d:4:d775:c942:f0bf:947f]) by smtp.gmail.com with ESMTPSA id n9-20020a05600c3b8900b003d1e1f421bfsm6597902wms.10.2022.12.06.09.16.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Dec 2022 09:16:35 -0800 (PST) From: Jann Horn To: stable@vger.kernel.org Subject: [PATCH stable 4.19 1/2] mm/khugepaged: fix GUP-fast interaction by sending IPI Date: Tue, 6 Dec 2022 18:16:07 +0100 Message-Id: <20221206171614.1183048-6-jannh@google.com> X-Mailer: git-send-email 2.39.0.rc0.267.gcb52ba06e7-goog In-Reply-To: <20221206171614.1183048-1-jannh@google.com> References: <20221206171614.1183048-1-jannh@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 2ba99c5e08812494bc57f319fb562f527d9bacd8 upstream. Since commit 70cbc3cc78a99 ("mm: gup: fix the fast GUP race against THP collapse"), the lockless_pages_from_mm() fastpath rechecks the pmd_t to ensure that the page table was not removed by khugepaged in between. However, lockless_pages_from_mm() still requires that the page table is not concurrently freed. Fix it by sending IPIs (if the architecture uses semi-RCU-style page table freeing) before freeing/reusing page tables. Link: https://lkml.kernel.org/r/20221129154730.2274278-2-jannh@google.com Link: https://lkml.kernel.org/r/20221128180252.1684965-2-jannh@google.com Link: https://lkml.kernel.org/r/20221125213714.4115729-2-jannh@google.com Fixes: ba76149f47d8 ("thp: khugepaged") Signed-off-by: Jann Horn Reviewed-by: Yang Shi Acked-by: David Hildenbrand Cc: John Hubbard Cc: Peter Xu Cc: Signed-off-by: Andrew Morton [manual backport: two of the three places in khugepaged that can free ptes were refactored into a common helper between 5.15 and 6.0; TLB flushing was refactored between 5.4 and 5.10; TLB flushing was refactored between 4.19 and 5.4; pmd collapse for PTE-mapped THP was only added in 5.4] Signed-off-by: Jann Horn --- include/asm-generic/tlb.h | 6 ++++++ mm/khugepaged.c | 2 ++ mm/memory.c | 5 +++++ 3 files changed, 13 insertions(+) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index db72ad39853b..737f5cb0dc84 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -61,6 +61,12 @@ struct mmu_table_batch { extern void tlb_table_flush(struct mmu_gather *tlb); extern void tlb_remove_table(struct mmu_gather *tlb, void *table); +void tlb_remove_table_sync_one(void); + +#else + +static inline void tlb_remove_table_sync_one(void) { } + #endif /* diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 5dd14ef2e1de..561660966435 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1045,6 +1045,7 @@ static void collapse_huge_page(struct mm_struct *mm, _pmd = pmdp_collapse_flush(vma, address, pmd); spin_unlock(pmd_ptl); mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); + tlb_remove_table_sync_one(); spin_lock(pte_ptl); isolated = __collapse_huge_page_isolate(vma, address, pte); @@ -1294,6 +1295,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) _pmd = pmdp_collapse_flush(vma, addr, pmd); spin_unlock(ptl); mm_dec_nr_ptes(mm); + tlb_remove_table_sync_one(); pte_free(mm, pmd_pgtable(_pmd)); } up_write(&mm->mmap_sem); diff --git a/mm/memory.c b/mm/memory.c index 800834cff4e6..b80ce6b3c8f4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -362,6 +362,11 @@ static void tlb_remove_table_smp_sync(void *arg) /* Simply deliver the interrupt */ } +void tlb_remove_table_sync_one(void) +{ + smp_call_function(tlb_remove_table_smp_sync, NULL, 1); +} + static void tlb_remove_table_one(void *table) { /* base-commit: c1ccef20f08e192228a2056808113b453d18c094 -- 2.39.0.rc0.267.gcb52ba06e7-goog