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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B0618FB3CF5 for ; Mon, 30 Mar 2026 10:11:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 277DB6B0098; Mon, 30 Mar 2026 06:11:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 202056B0099; Mon, 30 Mar 2026 06:11:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0F0CA6B009B; Mon, 30 Mar 2026 06:11:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id F29AB6B0098 for ; Mon, 30 Mar 2026 06:11:49 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id BC9578BFE7 for ; Mon, 30 Mar 2026 10:11:49 +0000 (UTC) X-FDA: 84602313138.23.B57A09F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf23.hostedemail.com (Postfix) with ESMTP id 28A4A140012 for ; Mon, 30 Mar 2026 10:11:47 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=PkFVBcKE; spf=pass (imf23.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774865508; 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=FkpjBBMDahVnoJHQTLrKky2w/Y+q9m6xuZg0sZyc/wU=; b=Zym6w7e4S/OsWvGyCd4WTrW2hMaYfne8cJo3NdsjpedtiSTTOk0F/o8wHG3HzEHYBgW7tS aYqxSBia1evSAiKjjPE9OZZTdzN34lkQxqZBnTbl+48rQINKA3gSCbiUVvfdrBHUU2+N1i RxsBt8hJn+30aanjAcsejiQYxkX098A= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774865508; a=rsa-sha256; cv=none; b=7o/Lti+40F1PzzOpiNXEYnBmWu8uLynYkRdOjqC+CWyTdB52EwRzxkQiW7CR+SWZBbp43C B8xTmZYxe6pMNWbIEEMy6j+GXhw3Cra0VjG87OGX2ZOnnbbaIFnHh3hoirfOZqs2ERYyAW vqqvhMLalW8lvs5NHY1Qz3gNU2GtQr8= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=PkFVBcKE; spf=pass (imf23.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 34A6540889; Mon, 30 Mar 2026 10:11:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D40C8C2BC9E; Mon, 30 Mar 2026 10:11:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774865507; bh=1DrXuSwiAhOzaulO5G9xZyzpNsLyxsrB7l2LjMZyGp0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PkFVBcKEy+nKe+MP3hw+nxp/uTTTK4Qt4cC8Bp1NGkORfgNDuWEFsMdvuEca3uIAO 7dmS1MwmwLrXJeSYaKHyDqI+hElmO5KM67rKEKP9DPwf1eYV0It5rn2IUMPVjXkBB3 DU4nzNtK+zF1YZwuOFrQHXDwbISsHEPADqec87BJiw7aBw9tCeB6LiKlD8QyEZezE7 BRmRNjLofhHABT3Lf0uBQvTeT4Gxz20Xj9nSclmPBkEqQphgeaY1cOnjKgR3PWMHdl oFTDblZOKQHdtqcmqPlvaB5b0Xzwzj3p4Q0cEswOxmJ3zV8dTl1qejLsSeKyEFda55 VHDlFfXmWMFVg== From: Mike Rapoport To: Andrew Morton Cc: Andrea Arcangeli , Andrei Vagin , Axel Rasmussen , Baolin Wang , David Hildenbrand , Harry Yoo , Hugh Dickins , James Houghton , "Liam R. Howlett" , "Lorenzo Stoakes (Oracle)" , "Matthew Wilcox (Oracle)" , Michal Hocko , Mike Rapoport , Muchun Song , Nikita Kalyazin , Oscar Salvador , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 03/15] userfaultfd: introduce mfill_establish_pmd() helper Date: Mon, 30 Mar 2026 13:11:04 +0300 Message-ID: <20260330101116.1117699-4-rppt@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260330101116.1117699-1-rppt@kernel.org> References: <20260330101116.1117699-1-rppt@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 28A4A140012 X-Stat-Signature: qnkyo545am8eptj8oppuskhutfp93rf9 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1774865507-346225 X-HE-Meta: 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 Jujghj4m QZnc7ebf+A4X6j2o= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Mike Rapoport (Microsoft)" There is a lengthy code chunk in mfill_atomic() that establishes the PMD for UFFDIO operations. This code may be called twice: first time when the copy is performed with VMA/mm locks held and the other time after the copy is retried with locks dropped. Move the code that establishes a PMD into a helper function so it can be reused later during refactoring of mfill_atomic_pte_copy(). Signed-off-by: Mike Rapoport (Microsoft) --- mm/userfaultfd.c | 102 ++++++++++++++++++++++++----------------------- 1 file changed, 52 insertions(+), 50 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index fa9622ec7279..291e5cfed431 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -157,6 +157,56 @@ static void uffd_mfill_unlock(struct vm_area_struct *vma) } #endif +static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + + pgd = pgd_offset(mm, address); + p4d = p4d_alloc(mm, pgd, address); + if (!p4d) + return NULL; + pud = pud_alloc(mm, p4d, address); + if (!pud) + return NULL; + /* + * Note that we didn't run this because the pmd was + * missing, the *pmd may be already established and in + * turn it may also be a trans_huge_pmd. + */ + return pmd_alloc(mm, pud, address); +} + +static int mfill_establish_pmd(struct mfill_state *state) +{ + struct mm_struct *dst_mm = state->ctx->mm; + pmd_t *dst_pmd, dst_pmdval; + + dst_pmd = mm_alloc_pmd(dst_mm, state->dst_addr); + if (unlikely(!dst_pmd)) + return -ENOMEM; + + dst_pmdval = pmdp_get_lockless(dst_pmd); + if (unlikely(pmd_none(dst_pmdval)) && + unlikely(__pte_alloc(dst_mm, dst_pmd))) + return -ENOMEM; + + dst_pmdval = pmdp_get_lockless(dst_pmd); + /* + * If the dst_pmd is THP don't override it and just be strict. + * (This includes the case where the PMD used to be THP and + * changed back to none after __pte_alloc().) + */ + if (unlikely(!pmd_present(dst_pmdval) || pmd_leaf(dst_pmdval))) + return -EEXIST; + if (unlikely(pmd_bad(dst_pmdval))) + return -EFAULT; + + state->pmd = dst_pmd; + return 0; +} + /* Check if dst_addr is outside of file's size. Must be called with ptl held. */ static bool mfill_file_over_size(struct vm_area_struct *dst_vma, unsigned long dst_addr) @@ -489,27 +539,6 @@ static int mfill_atomic_pte_poison(struct mfill_state *state) return ret; } -static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) -{ - pgd_t *pgd; - p4d_t *p4d; - pud_t *pud; - - pgd = pgd_offset(mm, address); - p4d = p4d_alloc(mm, pgd, address); - if (!p4d) - return NULL; - pud = pud_alloc(mm, p4d, address); - if (!pud) - return NULL; - /* - * Note that we didn't run this because the pmd was - * missing, the *pmd may be already established and in - * turn it may also be a trans_huge_pmd. - */ - return pmd_alloc(mm, pud, address); -} - #ifdef CONFIG_HUGETLB_PAGE /* * mfill_atomic processing for HUGETLB vmas. Note that this routine is @@ -742,7 +771,6 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, struct vm_area_struct *dst_vma; long copied = 0; ssize_t err; - pmd_t *dst_pmd; /* * Sanitize the command parameters: @@ -809,41 +837,15 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, while (state.src_addr < src_start + len) { VM_WARN_ON_ONCE(state.dst_addr >= dst_start + len); - pmd_t dst_pmdval; - - dst_pmd = mm_alloc_pmd(dst_mm, state.dst_addr); - if (unlikely(!dst_pmd)) { - err = -ENOMEM; + err = mfill_establish_pmd(&state); + if (err) break; - } - dst_pmdval = pmdp_get_lockless(dst_pmd); - if (unlikely(pmd_none(dst_pmdval)) && - unlikely(__pte_alloc(dst_mm, dst_pmd))) { - err = -ENOMEM; - break; - } - dst_pmdval = pmdp_get_lockless(dst_pmd); - /* - * If the dst_pmd is THP don't override it and just be strict. - * (This includes the case where the PMD used to be THP and - * changed back to none after __pte_alloc().) - */ - if (unlikely(!pmd_present(dst_pmdval) || - pmd_trans_huge(dst_pmdval))) { - err = -EEXIST; - break; - } - if (unlikely(pmd_bad(dst_pmdval))) { - err = -EFAULT; - break; - } /* * For shmem mappings, khugepaged is allowed to remove page * tables under us; pte_offset_map_lock() will deal with that. */ - state.pmd = dst_pmd; err = mfill_atomic_pte(&state); cond_resched(); -- 2.53.0