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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1657596558; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uxYP30zRX3+087a7ADNvtSYGr7OYdBOK6+qjv5apzug=; b=hJwVuNqkkZOCT+ZdmZYQen7zQ1mmtijAbglBtESiLm4BhdDuouiZyCPG2zfqJh+s9RoDC3 28Rj1W6j3bhEg6HSADHxX7h+AYV5T8sYmDT1Bpq4BESEKXsYO5hX/subvNXbTnwVZ1lPMo IW2TlH0I9a8yDuOLCGr/xPVYcwy5/fA= From: Naoya Horiguchi To: linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Mike Kravetz , Miaohe Lin , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , linux-kernel@vger.kernel.org Subject: [mm-unstable PATCH v6 2/8] mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry Date: Tue, 12 Jul 2022 12:28:52 +0900 Message-Id: <20220712032858.170414-3-naoya.horiguchi@linux.dev> In-Reply-To: <20220712032858.170414-1-naoya.horiguchi@linux.dev> References: <20220712032858.170414-1-naoya.horiguchi@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=hJwVuNqk; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf05.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 91.121.223.63 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657596560; 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-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=uxYP30zRX3+087a7ADNvtSYGr7OYdBOK6+qjv5apzug=; b=RA5o3lPM6n5uJl2NRgf3EcE5/nP5f0y4kCcHDzGcb+wMRXXAhSdBS6nMNJ7Qkdcr/BJ3dk f/SUH62YSk17MDtwzfOYAiZD6XE1eX9byjxFvQCIlOpOJFAc6l4ti5gEdHn2TUepynJ6ZI 0jngCrZiMStV5f7mbMcaWGiB8oh84c0= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657596560; a=rsa-sha256; cv=none; b=7bHWEfUmH7KEZ1HUy9Rwj1ALUsTyhUxbndFqfUfjLozW01UAtdvgtY4TCWqOvgDIDzZ719 tz3u4jrGI8DqHgHPPyh07P6JDcvCmnYEqRoEontA8UJZxbNyb7GxHqXH9KegcVI3w0rtaP vadunOuO/jBJEdYTaYxzS3o0X1oorlc= Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=hJwVuNqk; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf05.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 91.121.223.63 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev X-Rspam-User: X-Rspamd-Server: rspam08 X-Stat-Signature: dbrxd38cc97oqpqkox8kxnppbhqztseb X-Rspamd-Queue-Id: C994A100038 X-HE-Tag: 1657596559-84579 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: From: Naoya Horiguchi follow_pud_mask() does not support non-present pud entry now. As long as I tested on x86_64 server, follow_pud_mask() still simply returns no_page_table() for non-present_pud_entry() due to pud_bad(), so no severe user-visible effect should happen. But generally we should call follow_huge_pud() for non-present pud entry for 1GB hugetlb page. Update pud_huge() and follow_huge_pud() to handle non-present pud entries. The changes are similar to previous works for pud entries commit e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()") and commit cbef8478bee5 ("mm/hugetlb: pmd_huge() returns true for non-present hugepage"). Signed-off-by: Naoya Horiguchi Reviewed-by: Miaohe Lin Reviewed-by: Mike Kravetz --- v2 -> v3: - fixed typos in subject and description, - added comment on pud_huge(), - added comment about fallback for hwpoisoned entry, - updated initial check about FOLL_{PIN,GET} flags. --- arch/x86/mm/hugetlbpage.c | 8 +++++++- mm/hugetlb.c | 32 ++++++++++++++++++++++++++++++-- 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c index 509408da0da1..6b3033845c6d 100644 --- a/arch/x86/mm/hugetlbpage.c +++ b/arch/x86/mm/hugetlbpage.c @@ -30,9 +30,15 @@ int pmd_huge(pmd_t pmd) (pmd_val(pmd) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT; } +/* + * pud_huge() returns 1 if @pud is hugetlb related entry, that is normal + * hugetlb entry or non-present (migration or hwpoisoned) hugetlb entry. + * Otherwise, returns 0. + */ int pud_huge(pud_t pud) { - return !!(pud_val(pud) & _PAGE_PSE); + return !pud_none(pud) && + (pud_val(pud) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT; } #ifdef CONFIG_HUGETLB_PAGE diff --git a/mm/hugetlb.c b/mm/hugetlb.c index cf8ccee7654c..77119d93a0f9 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6978,10 +6978,38 @@ struct page * __weak follow_huge_pud(struct mm_struct *mm, unsigned long address, pud_t *pud, int flags) { - if (flags & (FOLL_GET | FOLL_PIN)) + struct page *page = NULL; + spinlock_t *ptl; + pte_t pte; + + if (WARN_ON_ONCE(flags & FOLL_PIN)) return NULL; - return pte_page(*(pte_t *)pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT); +retry: + ptl = huge_pte_lock(hstate_sizelog(PUD_SHIFT), mm, (pte_t *)pud); + if (!pud_huge(*pud)) + goto out; + pte = huge_ptep_get((pte_t *)pud); + if (pte_present(pte)) { + page = pud_page(*pud) + ((address & ~PUD_MASK) >> PAGE_SHIFT); + if (WARN_ON_ONCE(!try_grab_page(page, flags))) { + page = NULL; + goto out; + } + } else { + if (is_hugetlb_entry_migration(pte)) { + spin_unlock(ptl); + __migration_entry_wait(mm, (pte_t *)pud, ptl); + goto retry; + } + /* + * hwpoisoned entry is treated as no_page_table in + * follow_page_mask(). + */ + } +out: + spin_unlock(ptl); + return page; } struct page * __weak -- 2.25.1