From patchwork Tue Feb 13 21:57:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 13555746 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]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2D65C4829A for ; Tue, 13 Feb 2024 21:58:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5FDA68D0022; Tue, 13 Feb 2024 16:58:00 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 57B2B6B0082; Tue, 13 Feb 2024 16:58:00 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 380628D0022; Tue, 13 Feb 2024 16:58:00 -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 235036B007B for ; Tue, 13 Feb 2024 16:58:00 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id F3FAB80C69 for ; Tue, 13 Feb 2024 21:57:59 +0000 (UTC) X-FDA: 81788143878.01.38646FC Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) by imf30.hostedemail.com (Postfix) with ESMTP id 2A8CD8000E for ; Tue, 13 Feb 2024 21:57:57 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=SaJh9qpT; spf=pass (imf30.hostedemail.com: domain of 35eXLZQsKCBY7A60E324zDw2AA270.yA8749GJ-886Hwy6.AD2@flex--lokeshgidra.bounces.google.com designates 209.85.219.201 as permitted sender) smtp.mailfrom=35eXLZQsKCBY7A60E324zDw2AA270.yA8749GJ-886Hwy6.AD2@flex--lokeshgidra.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1707861478; 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-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=lSLmVkRgWUoN7XoRPV1r5JJdZzlBEVE8ndv4C2H5Jh8=; b=DxhATf3Wsdu7PI/YSmKubYLYKnhlBFQa93mY/yDxyUPrYe4PlSioXnyTwqtEi8ihhl38ju GPMsIL/ZhqH/BetEATDa8YJzPeyLheuFrdOTx6O6jh4tjYha5J0i+uI2BB2yL6MZD9y5uH /eplA8+qyzXTqyXHkomYg8LadT7Tdmk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1707861478; a=rsa-sha256; cv=none; b=f2YXZcFJaPBrkCP4FSJf3B/jRftee4KpvkSJj4vnNJIaRyO/0oqLGdwi6OwH/g/H8EhDIT oj3SXGVkF/kjdqy+rdkXE2zUfSz19WzLjyWdyO8PNnmohRVOOeuWF6eVlXy9pEoHWE2nu7 0ytdZjTvKVegYj3z3YgkVJ8647/9dAA= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=SaJh9qpT; spf=pass (imf30.hostedemail.com: domain of 35eXLZQsKCBY7A60E324zDw2AA270.yA8749GJ-886Hwy6.AD2@flex--lokeshgidra.bounces.google.com designates 209.85.219.201 as permitted sender) smtp.mailfrom=35eXLZQsKCBY7A60E324zDw2AA270.yA8749GJ-886Hwy6.AD2@flex--lokeshgidra.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-dc6ceade361so8528128276.0 for ; Tue, 13 Feb 2024 13:57:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1707861477; x=1708466277; darn=kvack.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=lSLmVkRgWUoN7XoRPV1r5JJdZzlBEVE8ndv4C2H5Jh8=; b=SaJh9qpTcTYV964mQSwdMztXKovwUgiVoEbwimXoGO3kJ0ke1fsInatKRm//heegjd oxoFqBDNzr63mVFQZEVBI6koiXIyQMXGgzkFacB5113B7LcVdE83fz6whnwXo4Wj8abQ DC/1jbMcPLkrcdg04wc3b8yLiZnHvuVPNZzWxuhfIyVhqTevXZfKeSzfTCM0bGsKRORy Hi1kC79vu6pyvl6OGh5/phlAHrMCW/B1ad5o42pU2EC2HWZxYQBkzSyzb+WHDPTgSYn8 6V9GFIcoRG+Gs8Tud1VHDYyuAZ9gTDawziHAePDyqOo3p4jcxY6hfJT9nmZE6yxHpCt4 pqTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707861477; x=1708466277; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=lSLmVkRgWUoN7XoRPV1r5JJdZzlBEVE8ndv4C2H5Jh8=; b=DtMKsNADQWrb1FMYM54JrZIONLqelAdq2qRqrRLTBgTWqdX23MhDKZKOBNBuVqLk1C WUGNm1wVtaEP+AeDNTLN/1/wBUCtUD21BHRhIS6V6AAGERIar7A5fWBlBo8xV40a+U5h UdvnGvIYixSXSLzmKvBYTExDjps+/+FoovGXp/iPgfrzb6U2/25zRkYVa5t+Pvr+j1OP nCL9dObFh9QGTyZJ6MrbhvW1vLZ/UeZWGRlaYNe2VBhWYeA+FW+7qcgwEmzMuNBg33u3 1Sw8rQY8gqmrbR/MRVzwWaOvLXMmEgvVDuvD9AZDC+3peROP5Y3tCKLkenJWoO107eF/ PfRw== X-Forwarded-Encrypted: i=1; AJvYcCU5eAwpOsvn98tURZL3W6tgIE/7qv7RmQTN/qNKmpU9doeI7ijoaPignJkyYIJ0TLbH9fCTmGyCpiokxlhrDjkBEao= X-Gm-Message-State: AOJu0YwwgoQxkgzDVFXP7gM1Q1Z6gnYL7C2Z0JYHVT4SYcOInyu93K0R SBy3P7tqAjRif/3HR8zzmIJVpyLJU4bD/s0Am31rivF5LoSq8c3uyxOyFLwbc0H7eCP6WCZHY2m /i58yk/7+c7nE+o5Ovi/SxA== X-Google-Smtp-Source: AGHT+IH954nIwdBLMKzG+Hi6faE6gUN1nsyORBxMb+9Ivpb9zj9IUDvp6eZkkvZZIh0bsvjZ4k7hqnmrecb1SwwavQ== X-Received: from lg.mtv.corp.google.com ([2620:15c:211:202:ce6c:821f:a756:b4b8]) (user=lokeshgidra job=sendgmr) by 2002:a05:6902:1509:b0:dc2:550b:a4f4 with SMTP id q9-20020a056902150900b00dc2550ba4f4mr86186ybu.1.1707861477294; Tue, 13 Feb 2024 13:57:57 -0800 (PST) Date: Tue, 13 Feb 2024 13:57:40 -0800 In-Reply-To: <20240213215741.3816570-1-lokeshgidra@google.com> Mime-Version: 1.0 References: <20240213215741.3816570-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.43.0.687.g38aa6559b0-goog Message-ID: <20240213215741.3816570-3-lokeshgidra@google.com> Subject: [PATCH v6 2/3] userfaultfd: protect mmap_changing with rw_sem in userfaulfd_ctx From: Lokesh Gidra To: akpm@linux-foundation.org Cc: lokeshgidra@google.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, selinux@vger.kernel.org, surenb@google.com, kernel-team@android.com, aarcange@redhat.com, peterx@redhat.com, david@redhat.com, axelrasmussen@google.com, bgeffon@google.com, willy@infradead.org, jannh@google.com, kaleshsingh@google.com, ngeoffray@google.com, timmurray@google.com, rppt@kernel.org, Liam.Howlett@oracle.com X-Stat-Signature: tamfnnt1b7y16cd9a1bw6rki9d5ogui6 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 2A8CD8000E X-Rspam-User: X-HE-Tag: 1707861477-488309 X-HE-Meta: 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 yNx3F6vJ 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 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: List-Subscribe: List-Unsubscribe: Increments and loads to mmap_changing are always in mmap_lock critical section. This ensures that if userspace requests event notification for non-cooperative operations (e.g. mremap), userfaultfd operations don't occur concurrently. This can be achieved by using a separate read-write semaphore in userfaultfd_ctx such that increments are done in write-mode and loads in read-mode, thereby eliminating the dependency on mmap_lock for this purpose. This is a preparatory step before we replace mmap_lock usage with per-vma locks in fill/move ioctls. Signed-off-by: Lokesh Gidra Reviewed-by: Mike Rapoport (IBM) --- fs/userfaultfd.c | 40 ++++++++++++---------- include/linux/userfaultfd_k.h | 31 ++++++++++-------- mm/userfaultfd.c | 62 ++++++++++++++++++++--------------- 3 files changed, 75 insertions(+), 58 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 58331b83d648..c00a021bcce4 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -685,12 +685,15 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs) ctx->flags = octx->flags; ctx->features = octx->features; ctx->released = false; + init_rwsem(&ctx->map_changing_lock); atomic_set(&ctx->mmap_changing, 0); ctx->mm = vma->vm_mm; mmgrab(ctx->mm); userfaultfd_ctx_get(octx); + down_write(&octx->map_changing_lock); atomic_inc(&octx->mmap_changing); + up_write(&octx->map_changing_lock); fctx->orig = octx; fctx->new = ctx; list_add_tail(&fctx->list, fcs); @@ -737,7 +740,9 @@ void mremap_userfaultfd_prep(struct vm_area_struct *vma, if (ctx->features & UFFD_FEATURE_EVENT_REMAP) { vm_ctx->ctx = ctx; userfaultfd_ctx_get(ctx); + down_write(&ctx->map_changing_lock); atomic_inc(&ctx->mmap_changing); + up_write(&ctx->map_changing_lock); } else { /* Drop uffd context if remap feature not enabled */ vma_start_write(vma); @@ -783,7 +788,9 @@ bool userfaultfd_remove(struct vm_area_struct *vma, return true; userfaultfd_ctx_get(ctx); + down_write(&ctx->map_changing_lock); atomic_inc(&ctx->mmap_changing); + up_write(&ctx->map_changing_lock); mmap_read_unlock(mm); msg_init(&ewq.msg); @@ -825,7 +832,9 @@ int userfaultfd_unmap_prep(struct vm_area_struct *vma, unsigned long start, return -ENOMEM; userfaultfd_ctx_get(ctx); + down_write(&ctx->map_changing_lock); atomic_inc(&ctx->mmap_changing); + up_write(&ctx->map_changing_lock); unmap_ctx->ctx = ctx; unmap_ctx->start = start; unmap_ctx->end = end; @@ -1709,9 +1718,8 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx, if (uffdio_copy.mode & UFFDIO_COPY_MODE_WP) flags |= MFILL_ATOMIC_WP; if (mmget_not_zero(ctx->mm)) { - ret = mfill_atomic_copy(ctx->mm, uffdio_copy.dst, uffdio_copy.src, - uffdio_copy.len, &ctx->mmap_changing, - flags); + ret = mfill_atomic_copy(ctx, uffdio_copy.dst, uffdio_copy.src, + uffdio_copy.len, flags); mmput(ctx->mm); } else { return -ESRCH; @@ -1761,9 +1769,8 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, goto out; if (mmget_not_zero(ctx->mm)) { - ret = mfill_atomic_zeropage(ctx->mm, uffdio_zeropage.range.start, - uffdio_zeropage.range.len, - &ctx->mmap_changing); + ret = mfill_atomic_zeropage(ctx, uffdio_zeropage.range.start, + uffdio_zeropage.range.len); mmput(ctx->mm); } else { return -ESRCH; @@ -1818,9 +1825,8 @@ static int userfaultfd_writeprotect(struct userfaultfd_ctx *ctx, return -EINVAL; if (mmget_not_zero(ctx->mm)) { - ret = mwriteprotect_range(ctx->mm, uffdio_wp.range.start, - uffdio_wp.range.len, mode_wp, - &ctx->mmap_changing); + ret = mwriteprotect_range(ctx, uffdio_wp.range.start, + uffdio_wp.range.len, mode_wp); mmput(ctx->mm); } else { return -ESRCH; @@ -1870,9 +1876,8 @@ static int userfaultfd_continue(struct userfaultfd_ctx *ctx, unsigned long arg) flags |= MFILL_ATOMIC_WP; if (mmget_not_zero(ctx->mm)) { - ret = mfill_atomic_continue(ctx->mm, uffdio_continue.range.start, - uffdio_continue.range.len, - &ctx->mmap_changing, flags); + ret = mfill_atomic_continue(ctx, uffdio_continue.range.start, + uffdio_continue.range.len, flags); mmput(ctx->mm); } else { return -ESRCH; @@ -1925,9 +1930,8 @@ static inline int userfaultfd_poison(struct userfaultfd_ctx *ctx, unsigned long goto out; if (mmget_not_zero(ctx->mm)) { - ret = mfill_atomic_poison(ctx->mm, uffdio_poison.range.start, - uffdio_poison.range.len, - &ctx->mmap_changing, 0); + ret = mfill_atomic_poison(ctx, uffdio_poison.range.start, + uffdio_poison.range.len, 0); mmput(ctx->mm); } else { return -ESRCH; @@ -2003,13 +2007,14 @@ static int userfaultfd_move(struct userfaultfd_ctx *ctx, if (mmget_not_zero(mm)) { mmap_read_lock(mm); - /* Re-check after taking mmap_lock */ + /* Re-check after taking map_changing_lock */ + down_read(&ctx->map_changing_lock); if (likely(!atomic_read(&ctx->mmap_changing))) ret = move_pages(ctx, mm, uffdio_move.dst, uffdio_move.src, uffdio_move.len, uffdio_move.mode); else ret = -EAGAIN; - + up_read(&ctx->map_changing_lock); mmap_read_unlock(mm); mmput(mm); } else { @@ -2216,6 +2221,7 @@ static int new_userfaultfd(int flags) ctx->flags = flags; ctx->features = 0; ctx->released = false; + init_rwsem(&ctx->map_changing_lock); atomic_set(&ctx->mmap_changing, 0); ctx->mm = current->mm; /* prevent the mm struct to be freed */ diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 691d928ee864..3210c3552976 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -69,6 +69,13 @@ struct userfaultfd_ctx { unsigned int features; /* released */ bool released; + /* + * Prevents userfaultfd operations (fill/move/wp) from happening while + * some non-cooperative event(s) is taking place. Increments are done + * in write-mode. Whereas, userfaultfd operations, which includes + * reading mmap_changing, is done under read-mode. + */ + struct rw_semaphore map_changing_lock; /* memory mappings are changing because of non-cooperative event */ atomic_t mmap_changing; /* mm with one ore more vmas attached to this userfaultfd_ctx */ @@ -113,22 +120,18 @@ extern int mfill_atomic_install_pte(pmd_t *dst_pmd, unsigned long dst_addr, struct page *page, bool newly_allocated, uffd_flags_t flags); -extern ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start, +extern ssize_t mfill_atomic_copy(struct userfaultfd_ctx *ctx, unsigned long dst_start, unsigned long src_start, unsigned long len, - atomic_t *mmap_changing, uffd_flags_t flags); -extern ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, + uffd_flags_t flags); +extern ssize_t mfill_atomic_zeropage(struct userfaultfd_ctx *ctx, unsigned long dst_start, - unsigned long len, - atomic_t *mmap_changing); -extern ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long dst_start, - unsigned long len, atomic_t *mmap_changing, - uffd_flags_t flags); -extern ssize_t mfill_atomic_poison(struct mm_struct *dst_mm, unsigned long start, - unsigned long len, atomic_t *mmap_changing, - uffd_flags_t flags); -extern int mwriteprotect_range(struct mm_struct *dst_mm, - unsigned long start, unsigned long len, - bool enable_wp, atomic_t *mmap_changing); + unsigned long len); +extern ssize_t mfill_atomic_continue(struct userfaultfd_ctx *ctx, unsigned long dst_start, + unsigned long len, uffd_flags_t flags); +extern ssize_t mfill_atomic_poison(struct userfaultfd_ctx *ctx, unsigned long start, + unsigned long len, uffd_flags_t flags); +extern int mwriteprotect_range(struct userfaultfd_ctx *ctx, unsigned long start, + unsigned long len, bool enable_wp); extern long uffd_wp_range(struct vm_area_struct *vma, unsigned long start, unsigned long len, bool enable_wp); diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 9cc93cc1330b..74aad0831e40 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -353,11 +353,11 @@ static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) * called with mmap_lock held, it will release mmap_lock before returning. */ static __always_inline ssize_t mfill_atomic_hugetlb( + struct userfaultfd_ctx *ctx, struct vm_area_struct *dst_vma, unsigned long dst_start, unsigned long src_start, unsigned long len, - atomic_t *mmap_changing, uffd_flags_t flags) { struct mm_struct *dst_mm = dst_vma->vm_mm; @@ -379,6 +379,7 @@ static __always_inline ssize_t mfill_atomic_hugetlb( * feature is not supported. */ if (uffd_flags_mode_is(flags, MFILL_ATOMIC_ZEROPAGE)) { + up_read(&ctx->map_changing_lock); mmap_read_unlock(dst_mm); return -EINVAL; } @@ -463,6 +464,7 @@ static __always_inline ssize_t mfill_atomic_hugetlb( cond_resched(); if (unlikely(err == -ENOENT)) { + up_read(&ctx->map_changing_lock); mmap_read_unlock(dst_mm); BUG_ON(!folio); @@ -473,12 +475,13 @@ static __always_inline ssize_t mfill_atomic_hugetlb( goto out; } mmap_read_lock(dst_mm); + down_read(&ctx->map_changing_lock); /* * 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 */ - if (mmap_changing && atomic_read(mmap_changing)) { + if (atomic_read(&ctx->mmap_changing)) { err = -EAGAIN; break; } @@ -501,6 +504,7 @@ static __always_inline ssize_t mfill_atomic_hugetlb( } out_unlock: + up_read(&ctx->map_changing_lock); mmap_read_unlock(dst_mm); out: if (folio) @@ -512,11 +516,11 @@ static __always_inline ssize_t mfill_atomic_hugetlb( } #else /* !CONFIG_HUGETLB_PAGE */ /* fail at build time if gcc attempts to use this */ -extern ssize_t mfill_atomic_hugetlb(struct vm_area_struct *dst_vma, +extern ssize_t mfill_atomic_hugetlb(struct userfaultfd_ctx *ctx, + struct vm_area_struct *dst_vma, unsigned long dst_start, unsigned long src_start, unsigned long len, - atomic_t *mmap_changing, uffd_flags_t flags); #endif /* CONFIG_HUGETLB_PAGE */ @@ -564,13 +568,13 @@ static __always_inline ssize_t mfill_atomic_pte(pmd_t *dst_pmd, return err; } -static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, +static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, unsigned long dst_start, unsigned long src_start, unsigned long len, - atomic_t *mmap_changing, uffd_flags_t flags) { + struct mm_struct *dst_mm = ctx->mm; struct vm_area_struct *dst_vma; ssize_t err; pmd_t *dst_pmd; @@ -600,8 +604,9 @@ static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, * 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 (mmap_changing && atomic_read(mmap_changing)) + if (atomic_read(&ctx->mmap_changing)) goto out_unlock; /* @@ -633,8 +638,8 @@ static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, * If this is a HUGETLB vma, pass off to appropriate routine */ if (is_vm_hugetlb_page(dst_vma)) - return mfill_atomic_hugetlb(dst_vma, dst_start, src_start, - len, mmap_changing, flags); + return mfill_atomic_hugetlb(ctx, dst_vma, dst_start, + src_start, len, flags); if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock; @@ -693,6 +698,7 @@ static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, if (unlikely(err == -ENOENT)) { void *kaddr; + up_read(&ctx->map_changing_lock); mmap_read_unlock(dst_mm); BUG_ON(!folio); @@ -723,6 +729,7 @@ static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, } out_unlock: + up_read(&ctx->map_changing_lock); mmap_read_unlock(dst_mm); out: if (folio) @@ -733,34 +740,33 @@ static __always_inline ssize_t mfill_atomic(struct mm_struct *dst_mm, return copied ? copied : err; } -ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start, +ssize_t mfill_atomic_copy(struct userfaultfd_ctx *ctx, unsigned long dst_start, unsigned long src_start, unsigned long len, - atomic_t *mmap_changing, uffd_flags_t flags) + uffd_flags_t flags) { - return mfill_atomic(dst_mm, dst_start, src_start, len, mmap_changing, + return mfill_atomic(ctx, dst_start, src_start, len, uffd_flags_set_mode(flags, MFILL_ATOMIC_COPY)); } -ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm, unsigned long start, - unsigned long len, atomic_t *mmap_changing) +ssize_t mfill_atomic_zeropage(struct userfaultfd_ctx *ctx, + unsigned long start, + unsigned long len) { - return mfill_atomic(dst_mm, start, 0, len, mmap_changing, + return mfill_atomic(ctx, start, 0, len, uffd_flags_set_mode(0, MFILL_ATOMIC_ZEROPAGE)); } -ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long start, - unsigned long len, atomic_t *mmap_changing, - uffd_flags_t flags) +ssize_t mfill_atomic_continue(struct userfaultfd_ctx *ctx, unsigned long start, + unsigned long len, uffd_flags_t flags) { - return mfill_atomic(dst_mm, start, 0, len, mmap_changing, + return mfill_atomic(ctx, start, 0, len, uffd_flags_set_mode(flags, MFILL_ATOMIC_CONTINUE)); } -ssize_t mfill_atomic_poison(struct mm_struct *dst_mm, unsigned long start, - unsigned long len, atomic_t *mmap_changing, - uffd_flags_t flags) +ssize_t mfill_atomic_poison(struct userfaultfd_ctx *ctx, unsigned long start, + unsigned long len, uffd_flags_t flags) { - return mfill_atomic(dst_mm, start, 0, len, mmap_changing, + return mfill_atomic(ctx, start, 0, len, uffd_flags_set_mode(flags, MFILL_ATOMIC_POISON)); } @@ -793,10 +799,10 @@ long uffd_wp_range(struct vm_area_struct *dst_vma, return ret; } -int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, - unsigned long len, bool enable_wp, - atomic_t *mmap_changing) +int mwriteprotect_range(struct userfaultfd_ctx *ctx, unsigned long start, + unsigned long len, bool enable_wp) { + struct mm_struct *dst_mm = ctx->mm; unsigned long end = start + len; unsigned long _start, _end; struct vm_area_struct *dst_vma; @@ -820,8 +826,9 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, * 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 (mmap_changing && atomic_read(mmap_changing)) + if (atomic_read(&ctx->mmap_changing)) goto out_unlock; err = -ENOENT; @@ -850,6 +857,7 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, err = 0; } out_unlock: + up_read(&ctx->map_changing_lock); mmap_read_unlock(dst_mm); return err; }