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 70246C4167B for ; Mon, 12 Dec 2022 17:32:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231779AbiLLRcx (ORCPT ); Mon, 12 Dec 2022 12:32:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232056AbiLLRct (ORCPT ); Mon, 12 Dec 2022 12:32:49 -0500 Received: from mail-wr1-x429.google.com (mail-wr1-x429.google.com [IPv6:2a00:1450:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D746C2AF1 for ; Mon, 12 Dec 2022 09:32:47 -0800 (PST) Received: by mail-wr1-x429.google.com with SMTP id m14so12868697wrh.7 for ; Mon, 12 Dec 2022 09:32:47 -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=Zzd+cgReRd/cuQfkZZ0Iv9J00C4W11v+MMtiDRkq67A=; b=Jsmqpq5C3Cd73HscgOpj8RSN93M4QWCeiA2xm31Gx31GaRH1ZvO2vepUrt3wQgaKql sYoFCrWW+613Ew9CwIro3GE8UuX0yRVCsE/QTWCQMFSmzrcXn8M3A/QYoNbev4XKcpxA fvXtMRUNQB7+/SK+/DpDn4i2IrdF4e+4TEfziBJSxJLpCZMSzzpAi74Eq4oyEIihlbu3 1H+ZdCCxOAo0zHGTmSbrrcfHZfj2Rihmd+NYICNl/MbTZjMfBmNqVgBnUBKXyAfbDj49 CK+XF0dHMdhNbVPPrmkAij7hhLrMBQaCZepj+5IpZgDTtTqKS6swGZ1yg9U89hKt9w/+ xnFw== 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=Zzd+cgReRd/cuQfkZZ0Iv9J00C4W11v+MMtiDRkq67A=; b=3lEBDe0zzqJQEQEV9EqNYEvXSrgiHTDhckCYE/LZRXI/UlM5AgrER7iTXv3V8nECPN mdtIZ/c2DPIufyQeqrMY100ABP2AGUnGD2iYvSLOHcR9SqCdPOH5h6tNpRlj6WgODcqy MvDgLN94EBk8GeNkIHOtioirN+HAaoiknxV8Fmj+3qqP1pkv11t2ESVemhruk8Sl5se7 dhJnHns/YBPw0F5waw5vz6dFfp3n3o9AKwcOB6mIb52JpExke7r2RXIIkWO0VxWGIFzP fKBodRH56hjHRKLRXCT90YIkUpsWBWI3UHhEQKd0etNixXKdNKR5SNYRjlazpO7JPWxl 0WQA== X-Gm-Message-State: ANoB5pnoPqgwRy39R1EOR0tAJI7yLd0Tpn55R6Gyn58osceSQU6MoP2D sj18kTf8vkQIE6VAtwInAP8kUM3pu4Q1JsFe X-Google-Smtp-Source: AA0mqf7HJpYBR7mzXwQ5UoOn2OJTvTexBaqnuPF7FpKxXOf7zGH9rcffNVUpvaVrkT5s/SiO4qc3Yw== X-Received: by 2002:a5d:5f04:0:b0:24b:b245:9f06 with SMTP id cl4-20020a5d5f04000000b0024bb2459f06mr738242wrb.1.1670866366392; Mon, 12 Dec 2022 09:32:46 -0800 (PST) Received: from localhost ([2a00:79e0:9d:4:d108:797c:2f44:5af6]) by smtp.gmail.com with ESMTPSA id o15-20020a05600c378f00b003c6d21a19a0sm9870274wmr.29.2022.12.12.09.32.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Dec 2022 09:32:45 -0800 (PST) From: Jann Horn To: stable@vger.kernel.org Subject: [PATCH v2 stable 4.9,4.14 1/2] mm/khugepaged: fix GUP-fast interaction by sending IPI Date: Mon, 12 Dec 2022 18:32:37 +0100 Message-Id: <20221212173238.963128-3-jannh@google.com> X-Mailer: git-send-email 2.39.0.rc1.256.g54fd8350bd-goog In-Reply-To: <20221212173238.963128-1-jannh@google.com> References: <20221212173238.963128-1-jannh@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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; ugly hack for s390 in <=4.19] Signed-off-by: Jann Horn --- added an incredibly ugly hack to work around the s390 issue reported in https://lore.kernel.org/all/Y5aaQqNH71IMVks0@sashalap/ include/asm-generic/tlb.h | 6 ++++++ mm/khugepaged.c | 15 +++++++++++++++ mm/memory.c | 5 +++++ 3 files changed, 26 insertions(+) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 5e7e4aaf36c5..43409a047480 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -60,6 +60,12 @@ 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 f426d42d629d..7825f3af5c6d 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -23,6 +23,19 @@ #include #include "internal.h" +/* gross hack for <=4.19 stable */ +#ifdef CONFIG_S390 +static void tlb_remove_table_smp_sync(void *arg) +{ + /* Simply deliver the interrupt */ +} + +static void tlb_remove_table_sync_one(void) +{ + smp_call_function(tlb_remove_table_smp_sync, NULL, 1); +} +#endif + enum scan_result { SCAN_FAIL, SCAN_SUCCEED, @@ -1046,6 +1059,7 @@ 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); @@ -1295,6 +1309,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) _pmd = pmdp_collapse_flush(vma, addr, pmd); spin_unlock(ptl); atomic_long_dec(&mm->nr_ptes); + 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 615cb3fe763d..0136af15ba18 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -373,6 +373,11 @@ 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: 179ef7fe86775fe32bd1bfe791887d1994ddcfb0 -- 2.39.0.rc1.256.g54fd8350bd-goog