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 CBD4AC00145 for ; Mon, 12 Dec 2022 17:32:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229536AbiLLRcv (ORCPT ); Mon, 12 Dec 2022 12:32:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231779AbiLLRcr (ORCPT ); Mon, 12 Dec 2022 12:32:47 -0500 Received: from mail-wm1-x333.google.com (mail-wm1-x333.google.com [IPv6:2a00:1450:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4556CDD0 for ; Mon, 12 Dec 2022 09:32:45 -0800 (PST) Received: by mail-wm1-x333.google.com with SMTP id ay40so6127153wmb.2 for ; Mon, 12 Dec 2022 09:32:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:from:to:cc:subject:date:message-id:reply-to; bh=S1PJ8+JDItZHFZ8yeGT+it4tq83ZN0ZD5+cvsta28E0=; b=jce7G+wxqgQjEiTpl15tJS2qRRWBzGS7ionwq+pPkHXeRjIalFrc10aL/rkC3eHDrx AvsVPgyO91UVrGF0++dVsYVHbvwod72hUH9AGa7lA/tLCdugTm1HhCGH66WqqIjB/V8S DHhABg539Di4OSn85zcoawYT61ywBRQD1y+GrEpZdxHgPnh0GMdETe9+WBh8d3yye85W vtpzULNs1B6VL73M8e5DDXItFxq+Rysz0O1duuF9QsoDVX7JLoKVKF+IoqQOeC/F/4YO RF2Jm4V48oEEzdlZ1IxQsWCw19kK6riC+qrwQUEi+kv0FFIgJkP+fQrY/Jzgg1bUl92W a8MA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=S1PJ8+JDItZHFZ8yeGT+it4tq83ZN0ZD5+cvsta28E0=; b=YCimkNJO4OlNfXOBa8uDhGiuu+KnwBbqtYE5d3kGBWM4OW62UkSy+Q/B7hJKHRt7B6 yqq6JiUKCdjVtTPme0Ksjuto0jdqYLfFRcEaYr2cFW716ckJRWACahKTJHTlHph34NzS k/9XCIMM0YvbubEY0ehV5tAppXCen4kDQsUKTMTuHo4CuoJHOkBlZMSMQUxc3EW2HNmF 5h6jxWj7UO9NMNSRQPFlX1o9FbLjNCkF8Ykd+xtCcOvts6IET5lWbM6U0AzLIwhcL8bQ 0MmBxm1ZXGIzkAsQ2Xok3ifjDMi+jqIP4gCEavhbucufGMvwlMuWg7luC43CC1b9C7H6 IiQw== X-Gm-Message-State: ANoB5pk+W3daPh7F2QYhhfMs6oI18ZDzmyg6Oz+u5bQUG0LD1lfKCiQ7 px0RGxk46u+hnz7mnGu0CmklzSJNMczQIGc1 X-Google-Smtp-Source: AA0mqf5gjgbRx+uozh610+2CNJ2DKI/uTLf0IJl8XIWi8+Lu/6uxkPN2NXFAc1QT/DEndFVzrcpMJg== X-Received: by 2002:a7b:cc8e:0:b0:3d1:f779:a187 with SMTP id p14-20020a7bcc8e000000b003d1f779a187mr688408wma.1.1670866363787; Mon, 12 Dec 2022 09:32:43 -0800 (PST) Received: from localhost ([2a00:79e0:9d:4:d108:797c:2f44:5af6]) by smtp.gmail.com with ESMTPSA id h5-20020a05600c2ca500b003c6bbe910fdsm12412476wmc.9.2022.12.12.09.32.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Dec 2022 09:32:43 -0800 (PST) From: Jann Horn To: stable@vger.kernel.org Subject: [PATCH v2 stable 4.19 1/2] mm/khugepaged: fix GUP-fast interaction by sending IPI Date: Mon, 12 Dec 2022 18:32:35 +0100 Message-Id: <20221212173238.963128-1-jannh@google.com> X-Mailer: git-send-email 2.39.0.rc1.256.g54fd8350bd-goog 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 needed in <=4.19 for s390] 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 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..0f217bb9b534 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, @@ -1045,6 +1058,7 @@ 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 +1308,7 @@ 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.rc1.256.g54fd8350bd-goog