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 72462CC6B00 for ; Thu, 2 Apr 2026 04:12:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D56606B0092; Thu, 2 Apr 2026 00:12:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D2DC16B0093; Thu, 2 Apr 2026 00:12:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C44076B0095; Thu, 2 Apr 2026 00:12:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id B932F6B0092 for ; Thu, 2 Apr 2026 00:12:36 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 5D0FD1A03C0 for ; Thu, 2 Apr 2026 04:12:36 +0000 (UTC) X-FDA: 84612294312.24.44A33C9 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf03.hostedemail.com (Postfix) with ESMTP id BE1262000D for ; Thu, 2 Apr 2026 04:12:34 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=O6LpCCvm; spf=pass (imf03.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 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=1775103154; 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=i4HMBcouyXvncFNKYcyI8NDDi+6JAJ4akpzdTsGezr4=; b=PNAv7lzQEt3v1SjS2QDBJW9l/WaYr0HT6YmJMaPO7OpJ2RefFnxjn9XV/9kLutEeRpg70x Y2T9AdU77X2CL43HbCeUxEWH42hRBl1ZjFPQvoP4mWgDTniBRgpnoyq2G/Qa//QJD+qXjp WPnDEuIHI03R5iAdwVgaCoMRbfmwjSI= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775103154; a=rsa-sha256; cv=none; b=rIXF2wpH/SXiNv37qZWJNuUv7gzAGQBnyzUyT5XKmyAz2cfKFYTHLlKiB+CTxPZ563V7yk RmdebbCFiLV4MmdgNarp4hSM7v0iy3JIWF/Hy7yc8RKiEawSxRkf84nLAe5pMiGUldKoo7 IKdt3yFCKBxcFHaJms8DMfYwS7QKVVI= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=O6LpCCvm; spf=pass (imf03.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 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 tor.source.kernel.org (Postfix) with ESMTP id 2DF0661866; Thu, 2 Apr 2026 04:12:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 990E0C19423; Thu, 2 Apr 2026 04:12:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775103153; bh=ioV0AIuZ8YXMYtun9GJuzmLOOslMKT49lU11YBPNu3A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O6LpCCvmyoASnA3Ul3G2H5VZP5ja5GFeNlfotTaUKFNEDJPBWQasBquvOFTxmwGkX 2Upft2ZfOHlPacRUK7hKJ4YWFsDP8lD9x7bySPvv4lBy5/UG0AiFm4Ol2PM5i2/iJ1 Yv61x1HnIEf/9L68PpHQkRLw0bsKdaXhzqGCBJCoSsfAuex6zu7ZBwJ3lQDiqjWFRE NhIoFNOU1Pv0K5Z6sMOtdiK4AwCqaW+XDKlgPwPV7nI03LG5YADmDduRjqjE3bcAiu Ygw1t0jmuQ3T5xJM1ZQvljWHrzU/5MAjRUmPVAF7L3I/U+C7JjqPjlu88cFRvLFqcv vtCJiSnyz6AJQ== 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 v4 04/15] userfaultfd: introduce mfill_get_vma() and mfill_put_vma() Date: Thu, 2 Apr 2026 07:11:45 +0300 Message-ID: <20260402041156.1377214-5-rppt@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260402041156.1377214-1-rppt@kernel.org> References: <20260402041156.1377214-1-rppt@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: BE1262000D X-Stat-Signature: ejjp4d1sseyugkm4mu3rgzbs3ruwxaga X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1775103154-421773 X-HE-Meta: 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 Dj3mjibL JxgogUapEQMVvIPjEUVWvoHT0mxmikhx/lR08PJeqXmIQOad679+zCAXiwD+AQYieUG//QlTRvy3o4doxkdl3XM80M4XbrrSs2WNvMaDN2RnzG6WNX9V4va61tJB5eKZBJWu1Kpm0rK78oIHX3g3dD+cTuCH7EAIbn/52xL6vL6+qjZZggMUeQb8jAe5DLEm3Gi8PhaPVU7fbEQqb8fWPo8G4L25OIJzQSk5h0Yb4gVbDys+DY/9eCkIQKx/SXhveZwwoE0wklVhqdMWPk1x3oMcV4+b2/TY6JJ9wCEk3lHZVAa4= 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. [avagin@google.com: fix lock leak in mfill_get_vma()] Link: https://lkml.kernel.org/r/20260316173829.1126728-1-avagin@google.com Signed-off-by: Mike Rapoport (Microsoft) Signed-off-by: Andrei Vagin --- mm/userfaultfd.c | 125 ++++++++++++++++++++++++++++------------------- 1 file changed, 75 insertions(+), 50 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index f653fb3f74df..c6a38db45343 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -157,6 +157,75 @@ static void uffd_mfill_unlock(struct vm_area_struct *vma) } #endif +static void mfill_put_vma(struct mfill_state *state) +{ + if (!state->vma) + return; + + 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); + state->vma = dst_vma; + 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)) + return 0; + + 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; + + 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; @@ -767,8 +836,6 @@ 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; @@ -783,56 +850,17 @@ 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; - } - state.vma = 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 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; - while (state.src_addr < src_start + len) { VM_WARN_ON_ONCE(state.dst_addr >= dst_start + len); @@ -851,8 +879,7 @@ 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); @@ -881,9 +908,7 @@ 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); -- 2.53.0