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 A4DCFFCC056 for ; Fri, 6 Mar 2026 17:18:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 14FCD6B009D; Fri, 6 Mar 2026 12:18:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 107EE6B009E; Fri, 6 Mar 2026 12:18:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F2B3D6B009F; Fri, 6 Mar 2026 12:18:53 -0500 (EST) 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 E483B6B009D for ; Fri, 6 Mar 2026 12:18:53 -0500 (EST) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id A5ED5C23DC for ; Fri, 6 Mar 2026 17:18:53 +0000 (UTC) X-FDA: 84516298146.11.D266D60 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf13.hostedemail.com (Postfix) with ESMTP id 0105920013 for ; Fri, 6 Mar 2026 17:18:51 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=e0ECtBkC; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772817532; 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=9I7GcAyNMQ4h1nGDO3nrcx8C3Qmu+bCHtWHFR0YCues=; b=GzTg0On5pqxiS+IXQJUa+ykaczuQlarZQm/gcqcktigfcRQP/T4dVkIemrYHQoe3uDvPsR zxDMu5fbUUk0ZowY4O4ZMaILVJenMAI6P4wXXs7zCfi6c0qGZqCriO9Cnlb2+DcZTIE4rl voZ/dydhrz2s0ualu+OYK1R7rBGzkYQ= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772817532; a=rsa-sha256; cv=none; b=fjzLBAf7hJzfGRFccreuN4XCv973VTANo+046Sy/YnBoOkqkTMJjOaMKytaVFtHoiZnI4C dnFd7YgXwknI1o3ZPglQCMbMoApfpeefxbW0ykIoZpfd3SXXgytpOdx31/qc3wicHO0/ST +lX4hu7D7fqHOeZcG/zSoAxkLWQ8UJM= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=e0ECtBkC; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of rppt@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=rppt@kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 325A2419A0; Fri, 6 Mar 2026 17:18:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5992AC4CEF7; Fri, 6 Mar 2026 17:18:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772817531; bh=G5arZbl8cQ1Z8+AqNUYSv0raYqzUJNHuE3AX6opuyHg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e0ECtBkCqhwlPUhpp20EDW+OTbsO/AwZiJOU8EVYFYjbLEOyU/XGLaAJ7uTlhSiah P8aV4/SPGl5vj+fQEn4d4QaUgyOY/3GUt2qQ4j2J4/5ygt1wuZJ1nH1U88SQ2VETvY GGfEz46WwjatfHliclfeBvPhTpZyYow7bP9jvr5yGANcXBimwFy/o+ho67ia/OCRYr v2AKW/h1tbBX4pmQYCaxLmMITsalTlShiLAHSmWCmqUAxYFat6eCslXF4NSDjm86A/ l8Yx5r1NPEasv72Jw2fTXxml9jJdYhvB7Xk8tq4oZj3CAf4W3iBrq2EHnRPJvZZMco C4uhnR215Vu0g== From: Mike Rapoport To: Andrew Morton Cc: Andrea Arcangeli , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , "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 v2 04/15] userfaultfd: introduce mfill_get_vma() and mfill_put_vma() Date: Fri, 6 Mar 2026 19:18:04 +0200 Message-ID: <20260306171815.3160826-5-rppt@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260306171815.3160826-1-rppt@kernel.org> References: <20260306171815.3160826-1-rppt@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 0105920013 X-Stat-Signature: tgwrtjyjsk98kdmpqk815qiysdbgkp7n X-Rspam-User: X-HE-Tag: 1772817531-477429 X-HE-Meta: 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 u/HZTHvQ /1DQIfimcuqB2uoNQYz1DI2J2mzohoBFIVLAAEeiqPjPzjywHpL0+9uDBoUqO0N63mr4QrQ4cziEodHL/0lTMVkE/jyCsYFoX/j7+K/5rShAfdTCm0QimMwBvKDpsxD73xP5DgiDR4Am4wXUPFQxQzPvN+rOSfwaqaPvTH4eaS/tMgftP74n3Qa7zS4/tIpKg8ILJCkXXUBVWy25QRihmQeW4savYij0DFNzshE74qTLliwD3UWbILD/NpLGg1/9dNdE8H+2PKaKhF0IEJhuw5ETpJQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Mike Rapoport (Microsoft)" Split the code that finds, locks and verifies VMA from mfill_atomic() into a helper function. This function will be used later during refactoring of mfill_atomic_pte_copy(). Add a counterpart mfill_put_vma() helper that unlocks the VMA and releases map_changing_lock. Signed-off-by: Mike Rapoport (Microsoft) --- mm/userfaultfd.c | 124 ++++++++++++++++++++++++++++------------------- 1 file changed, 73 insertions(+), 51 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 224b55804f99..baff11e83101 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -157,6 +157,73 @@ static void uffd_mfill_unlock(struct vm_area_struct *vma) } #endif +static void mfill_put_vma(struct mfill_state *state) +{ + up_read(&state->ctx->map_changing_lock); + uffd_mfill_unlock(state->vma); + state->vma = NULL; +} + +static int mfill_get_vma(struct mfill_state *state) +{ + struct userfaultfd_ctx *ctx = state->ctx; + uffd_flags_t flags = state->flags; + struct vm_area_struct *dst_vma; + int err; + + /* + * Make sure the vma is not shared, that the dst range is + * both valid and fully within a single existing vma. + */ + dst_vma = uffd_mfill_lock(ctx->mm, state->dst_start, state->len); + if (IS_ERR(dst_vma)) + return PTR_ERR(dst_vma); + + /* + * If memory mappings are changing because of non-cooperative + * operation (e.g. mremap) running in parallel, bail out and + * request the user to retry later + */ + down_read(&ctx->map_changing_lock); + err = -EAGAIN; + if (atomic_read(&ctx->mmap_changing)) + goto out_unlock; + + err = -EINVAL; + + /* + * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but + * it will overwrite vm_ops, so vma_is_anonymous must return false. + */ + if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && + dst_vma->vm_flags & VM_SHARED)) + goto out_unlock; + + /* + * validate 'mode' now that we know the dst_vma: don't allow + * a wrprotect copy if the userfaultfd didn't register as WP. + */ + if ((flags & MFILL_ATOMIC_WP) && !(dst_vma->vm_flags & VM_UFFD_WP)) + goto out_unlock; + + if (is_vm_hugetlb_page(dst_vma)) + goto out; + + if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) + goto out_unlock; + if (!vma_is_shmem(dst_vma) && + uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) + goto out_unlock; + +out: + state->vma = dst_vma; + return 0; + +out_unlock: + mfill_put_vma(state); + return err; +} + static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) { pgd_t *pgd; @@ -768,8 +835,6 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, .src_addr = src_start, .dst_addr = dst_start, }; - struct mm_struct *dst_mm = ctx->mm; - struct vm_area_struct *dst_vma; long copied = 0; ssize_t err; @@ -784,57 +849,17 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, VM_WARN_ON_ONCE(dst_start + len <= dst_start); retry: - /* - * Make sure the vma is not shared, that the dst range is - * both valid and fully within a single existing vma. - */ - dst_vma = uffd_mfill_lock(dst_mm, dst_start, len); - if (IS_ERR(dst_vma)) { - err = PTR_ERR(dst_vma); + err = mfill_get_vma(&state); + if (err) goto out; - } - - /* - * If memory mappings are changing because of non-cooperative - * operation (e.g. mremap) running in parallel, bail out and - * request the user to retry later - */ - down_read(&ctx->map_changing_lock); - err = -EAGAIN; - if (atomic_read(&ctx->mmap_changing)) - goto out_unlock; - - err = -EINVAL; - /* - * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but - * it will overwrite vm_ops, so vma_is_anonymous must return false. - */ - if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && - dst_vma->vm_flags & VM_SHARED)) - goto out_unlock; - - /* - * validate 'mode' now that we know the dst_vma: don't allow - * a wrprotect copy if the userfaultfd didn't register as WP. - */ - if ((flags & MFILL_ATOMIC_WP) && !(dst_vma->vm_flags & VM_UFFD_WP)) - goto out_unlock; /* * If this is a HUGETLB vma, pass off to appropriate routine */ - if (is_vm_hugetlb_page(dst_vma)) - return mfill_atomic_hugetlb(ctx, dst_vma, dst_start, + if (is_vm_hugetlb_page(state.vma)) + return mfill_atomic_hugetlb(ctx, state.vma, dst_start, src_start, len, flags); - if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) - goto out_unlock; - if (!vma_is_shmem(dst_vma) && - uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) - goto out_unlock; - - state.vma = dst_vma; - while (state.src_addr < src_start + len) { VM_WARN_ON_ONCE(state.dst_addr >= dst_start + len); @@ -853,8 +878,7 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, if (unlikely(err == -ENOENT)) { void *kaddr; - up_read(&ctx->map_changing_lock); - uffd_mfill_unlock(state.vma); + mfill_put_vma(&state); VM_WARN_ON_ONCE(!state.folio); kaddr = kmap_local_folio(state.folio, 0); @@ -883,9 +907,7 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, break; } -out_unlock: - up_read(&ctx->map_changing_lock); - uffd_mfill_unlock(state.vma); + mfill_put_vma(&state); out: if (state.folio) folio_put(state.folio); -- 2.51.0