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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E05D2C2B9F4 for ; Mon, 28 Jun 2021 14:38:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C844E61C75 for ; Mon, 28 Jun 2021 14:38:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234321AbhF1Ok3 (ORCPT ); Mon, 28 Jun 2021 10:40:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:43974 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235027AbhF1OjG (ORCPT ); Mon, 28 Jun 2021 10:39:06 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BA2BB61C7F; Mon, 28 Jun 2021 14:31:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624890683; bh=288Uuo94dswDT69PaMhlPM7axKfmtn2qpanan0dG4O4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H9JiVxsumk6JFaXs9bRH8ple3GT0izI7mg44Ap0Zak+cVE2bPofegTNEifIbLG79D 3qRFu6tAwerdyhl52+gW8z31ycjs3pCWS1VvO1z5Jxtt5OfLR4tZ8hCYLejbJvlfvU X6UzTahvrqGaJ/5Ug4ITQPXvoAvIvPDP1fYlsqMq7yAVWsOdjJJjq0wFzhs36jNoaj DEJLWxkC6cuTknaL0eDHiZk9MA5ErfBKzgKHKFxxobgTXzPHHm2Wnc5gyppyPsX2kw /5/IC/C6J7Eax7aw4wpHJfItGX7Y8ZFm18ShpSn8gmDwnDWie2VX1TuQH2kbHG/aVj GtdLYLzJuaTig== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Hugh Dickins , Neel Natu , Matthew Wilcox , Thomas Gleixner , "Kirill A. Shutemov" , Zhang Yi , Mel Gorman , Mike Kravetz , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , Andrew Morton , Linus Torvalds , Greg Kroah-Hartman Subject: [PATCH 5.4 66/71] mm, futex: fix shared futex pgoff on shmem huge page Date: Mon, 28 Jun 2021 10:29:59 -0400 Message-Id: <20210628143004.32596-67-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210628143004.32596-1-sashal@kernel.org> References: <20210628143004.32596-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.4.129-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.4.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.4.129-rc1 X-KernelTest-Deadline: 2021-06-30T14:29+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hugh Dickins [ Upstream commit fe19bd3dae3d15d2fbfdb3de8839a6ea0fe94264 ] If more than one futex is placed on a shmem huge page, it can happen that waking the second wakes the first instead, and leaves the second waiting: the key's shared.pgoff is wrong. When 3.11 commit 13d60f4b6ab5 ("futex: Take hugepages into account when generating futex_key"), the only shared huge pages came from hugetlbfs, and the code added to deal with its exceptional page->index was put into hugetlb source. Then that was missed when 4.8 added shmem huge pages. page_to_pgoff() is what others use for this nowadays: except that, as currently written, it gives the right answer on hugetlbfs head, but nonsense on hugetlbfs tails. Fix that by calling hugetlbfs-specific hugetlb_basepage_index() on PageHuge tails as well as on head. Yes, it's unconventional to declare hugetlb_basepage_index() there in pagemap.h, rather than in hugetlb.h; but I do not expect anything but page_to_pgoff() ever to need it. [akpm@linux-foundation.org: give hugetlb_basepage_index() prototype the correct scope] Link: https://lkml.kernel.org/r/b17d946b-d09-326e-b42a-52884c36df32@google.com Fixes: 800d8c63b2e9 ("shmem: add huge pages support") Reported-by: Neel Natu Signed-off-by: Hugh Dickins Reviewed-by: Matthew Wilcox (Oracle) Acked-by: Thomas Gleixner Cc: "Kirill A. Shutemov" Cc: Zhang Yi Cc: Mel Gorman Cc: Mike Kravetz Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Darren Hart Cc: Davidlohr Bueso Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Note on stable backport: leave redundant #include in kernel/futex.c, to avoid conflict over the header files included. Signed-off-by: Hugh Dickins Signed-off-by: Greg Kroah-Hartman --- include/linux/hugetlb.h | 16 ---------------- include/linux/pagemap.h | 13 +++++++------ kernel/futex.c | 2 +- mm/hugetlb.c | 5 +---- 4 files changed, 9 insertions(+), 27 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index fc717aeb2b3d..a0513c444446 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -469,17 +469,6 @@ static inline int hstate_index(struct hstate *h) return h - hstates; } -pgoff_t __basepage_index(struct page *page); - -/* Return page->index in PAGE_SIZE units */ -static inline pgoff_t basepage_index(struct page *page) -{ - if (!PageCompound(page)) - return page->index; - - return __basepage_index(page); -} - extern int dissolve_free_huge_page(struct page *page); extern int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn); @@ -695,11 +684,6 @@ static inline int hstate_index(struct hstate *h) return 0; } -static inline pgoff_t basepage_index(struct page *page) -{ - return page->index; -} - static inline int dissolve_free_huge_page(struct page *page) { return 0; diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 37a4d9e32cd3..8543b1aaa529 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -397,7 +397,7 @@ static inline struct page *read_mapping_page(struct address_space *mapping, } /* - * Get index of the page with in radix-tree + * Get index of the page within radix-tree (but not for hugetlb pages). * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE) */ static inline pgoff_t page_to_index(struct page *page) @@ -416,15 +416,16 @@ static inline pgoff_t page_to_index(struct page *page) return pgoff; } +extern pgoff_t hugetlb_basepage_index(struct page *page); + /* - * Get the offset in PAGE_SIZE. - * (TODO: hugepage should have ->index in PAGE_SIZE) + * Get the offset in PAGE_SIZE (even for hugetlb pages). + * (TODO: hugetlb pages should have ->index in PAGE_SIZE) */ static inline pgoff_t page_to_pgoff(struct page *page) { - if (unlikely(PageHeadHuge(page))) - return page->index << compound_order(page); - + if (unlikely(PageHuge(page))) + return hugetlb_basepage_index(page); return page_to_index(page); } diff --git a/kernel/futex.c b/kernel/futex.c index 375e7e98e301..f82879ae6577 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -737,7 +737,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, enum futex_a key->both.offset |= FUT_OFF_INODE; /* inode-based key */ key->shared.i_seq = get_inode_sequence_number(inode); - key->shared.pgoff = basepage_index(tail); + key->shared.pgoff = page_to_pgoff(tail); rcu_read_unlock(); } diff --git a/mm/hugetlb.c b/mm/hugetlb.c index fe15e7d8220a..95a32749af4d 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1461,15 +1461,12 @@ int PageHeadHuge(struct page *page_head) return get_compound_page_dtor(page_head) == free_huge_page; } -pgoff_t __basepage_index(struct page *page) +pgoff_t hugetlb_basepage_index(struct page *page) { struct page *page_head = compound_head(page); pgoff_t index = page_index(page_head); unsigned long compound_idx; - if (!PageHuge(page_head)) - return page_index(page); - if (compound_order(page_head) >= MAX_ORDER) compound_idx = page_to_pfn(page) - page_to_pfn(page_head); else -- 2.30.2