From nobody Wed Dec 17 08:54:19 2025 Received: from mail-io1-f73.google.com (mail-io1-f73.google.com [209.85.166.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C60B61EE01F for ; Thu, 20 Mar 2025 06:39:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742452792; cv=none; b=p8SimSohKb+rtmeoRIKAnWIQ/AvU175JXZ8fsAhPMpBrJMz69lc9Rrdrz8/4jzuVil5+QkaXnRW94CyNYYhE6BaSVvc5c5Lu7rtMz58LT48o8MW1eH9BAnbbKnjF+7TYqim2uc2uGHH4DWvGB0dkJJpWr4mnqrf7TpkQmqeZMqM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742452792; c=relaxed/simple; bh=GGGsjxJMNQjlKcl7gJ/10cnjYtrTd6brHOM5zCrOplI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=s78g8qE3KcI0cD73TU3y2mMp0SG8kpotb8K+Tw27nX0imBePePjBqAtALiDVDafbBoVZY1PaIsYyNzUcLBxuA4bKxJT36YbscaCVPNJCjB7QptCLSOvmXPfwVu9+jM9qzMeoijdOmId2kHQyZaYLbDFs3WE8cy9F4CJI0LGKsCw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--avagin.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=NSeLspLx; arc=none smtp.client-ip=209.85.166.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--avagin.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="NSeLspLx" Received: by mail-io1-f73.google.com with SMTP id ca18e2360f4ac-85b4ee2e69bso41037339f.2 for ; Wed, 19 Mar 2025 23:39:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1742452789; x=1743057589; darn=vger.kernel.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=h+zYWV6NSopuldnNVazhY6YUnTYuwrgpgyF3WHeSVI8=; b=NSeLspLxbeNdCL94XY08vBx9yNnirfvjiNL3NVkGOZ/O7Yw0TM6cTTabwFs6IcHmyT rD6jrdJ536gqlo3QEwMYOobzi97er6AX09U9p60PuIeVXK655fwe6oe5HGRUWxxPNLKm 4hiuOQhhcjfLbqc8fWD1hcA8MkHGp+tKLANWi/FLxNaj6QNAckBxpDlawUdiDCE85zBR /PmHaqVHdCRbcgjeVMRPgZ1zMZmAuSWfJr6AnD+0g5VWehmbBuz2cUP2WQA2ayxFpZYo e4WFwgOZSkAGidhhcbq3b6qGENLxgN2eMkQtlaZmUi1HD6cMbm746hq5GsVNpgGQqvfe 5bkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1742452789; x=1743057589; 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=h+zYWV6NSopuldnNVazhY6YUnTYuwrgpgyF3WHeSVI8=; b=oadrQDwjRhdS3JAGhClIkrDpll9B/s7cSEwfEIF9OKvvLK4J54tz6aDAeaWtq4QeyK al+8KTZ3Hy2O9L7r3S8rf0UbKTyUOHW3Mi8riAPzJgzb9APh0er+N88UJ5S41F2fy5H3 c1YzX5h1irrtbqWF2DjaYItbu/B0kg1t1HdY7rUWam+1MDUhJducmXSoayFtZP7apIEl +PzHgzzS2VNKf6yQdr6si2c4ZO8WLeg3Kl+3PW8by1L+bLgQH1xf4/vSke3J7fZZaWY2 7EtxE+h/j7ovuYaa/rqQGfOvoUI1/piU8OCrmI57k6qHvFVnZkmCgP9M4rAvYJJv0mMe msnQ== X-Gm-Message-State: AOJu0Yx33M+yr2eJ60hJEObJP9oCLRq/eZUDPIFHYLCaoLc7ZGYUoFSj GwqeH5Mc2rI/ZmgFn+iA54Q9M8x7VdG67LpO5QnCgcZILh5zaHakKfE4Gy7ktUgsbxCO6WmpqmK c9w== X-Google-Smtp-Source: AGHT+IEbcL33dk/wm6GLcLtAt9md7WDVC/RMdK0m0WYXEIIuByDZLRnpM5nzkyuglrbRs0eWMcYPoPCXpKg= X-Received: from iobbw12.prod.google.com ([2002:a05:6602:398c:b0:85d:9d10:cab7]) (user=avagin job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6602:4c8d:b0:85b:46d7:1886 with SMTP id ca18e2360f4ac-85e137da946mr646941939f.7.1742452788937; Wed, 19 Mar 2025 23:39:48 -0700 (PDT) Date: Thu, 20 Mar 2025 06:39:02 +0000 In-Reply-To: <20250320063903.2685882-1-avagin@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250320063903.2685882-1-avagin@google.com> X-Mailer: git-send-email 2.49.0.rc1.451.g8f38331e32-goog Message-ID: <20250320063903.2685882-2-avagin@google.com> Subject: [PATCH 1/2] fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions From: Andrei Vagin To: Lorenzo Stoakes , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, David Hildenbrand , Shuah Khan , Jonathan Corbet , Andrei Vagin Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Andrei Vagin Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose information about guard regions. This allows userspace tools, such as CRIU, to detect and handle guard regions. Signed-off-by: Andrei Vagin Acked-by: David Hildenbrand Reviewed-by: Lorenzo Stoakes --- Documentation/admin-guide/mm/pagemap.rst | 1 + fs/proc/task_mmu.c | 8 ++++++-- include/uapi/linux/fs.h | 1 + 3 files changed, 8 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin= -guide/mm/pagemap.rst index a297e824f990..7997b67ffc97 100644 --- a/Documentation/admin-guide/mm/pagemap.rst +++ b/Documentation/admin-guide/mm/pagemap.rst @@ -234,6 +234,7 @@ Following flags about pages are currently supported: - ``PAGE_IS_PFNZERO`` - Page has zero PFN - ``PAGE_IS_HUGE`` - Page is PMD-mapped THP or Hugetlb backed - ``PAGE_IS_SOFT_DIRTY`` - Page is soft-dirty +- ``PAGE_IS_GUARD`` - Page is a guard region =20 The ``struct pm_scan_arg`` is used as the argument of the IOCTL. =20 diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index c17615e21a5d..698d660bfee4 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -2067,7 +2067,8 @@ static int pagemap_release(struct inode *inode, struc= t file *file) #define PM_SCAN_CATEGORIES (PAGE_IS_WPALLOWED | PAGE_IS_WRITTEN | \ PAGE_IS_FILE | PAGE_IS_PRESENT | \ PAGE_IS_SWAPPED | PAGE_IS_PFNZERO | \ - PAGE_IS_HUGE | PAGE_IS_SOFT_DIRTY) + PAGE_IS_HUGE | PAGE_IS_SOFT_DIRTY | \ + PAGE_IS_GUARD) #define PM_SCAN_FLAGS (PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC) =20 struct pagemap_scan_private { @@ -2108,8 +2109,11 @@ static unsigned long pagemap_page_category(struct pa= gemap_scan_private *p, if (!pte_swp_uffd_wp_any(pte)) categories |=3D PAGE_IS_WRITTEN; =20 + swp =3D pte_to_swp_entry(pte); + if (is_guard_swp_entry(swp)) + categories |=3D PAGE_IS_GUARD; + if (p->masks_of_interest & PAGE_IS_FILE) { - swp =3D pte_to_swp_entry(pte); if (is_pfn_swap_entry(swp) && !folio_test_anon(pfn_swap_entry_folio(swp))) categories |=3D PAGE_IS_FILE; diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 2bbe00cf1248..8aa66c5f69b7 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -363,6 +363,7 @@ typedef int __bitwise __kernel_rwf_t; #define PAGE_IS_PFNZERO (1 << 5) #define PAGE_IS_HUGE (1 << 6) #define PAGE_IS_SOFT_DIRTY (1 << 7) +#define PAGE_IS_GUARD (1 << 8) =20 /* * struct page_region - Page region with flags --=20 2.49.0.rc1.451.g8f38331e32-goog From nobody Wed Dec 17 08:54:19 2025 Received: from mail-io1-f73.google.com (mail-io1-f73.google.com [209.85.166.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9AB6E1EF395 for ; 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Wed, 19 Mar 2025 23:39:50 -0700 (PDT) Date: Thu, 20 Mar 2025 06:39:03 +0000 In-Reply-To: <20250320063903.2685882-1-avagin@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250320063903.2685882-1-avagin@google.com> X-Mailer: git-send-email 2.49.0.rc1.451.g8f38331e32-goog Message-ID: <20250320063903.2685882-3-avagin@google.com> Subject: [PATCH 2/2] selftests/mm: add PAGEMAP_SCAN guard region test From: Andrei Vagin To: Lorenzo Stoakes , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, David Hildenbrand , Shuah Khan , Jonathan Corbet , Andrei Vagin Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Andrei Vagin Add a selftest to verify the PAGEMAP_SCAN ioctl correctly reports guard regions using the newly introduced PAGE_IS_GUARD flag. Signed-off-by: Andrei Vagin --- tools/testing/selftests/mm/guard-regions.c | 53 ++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/sel= ftests/mm/guard-regions.c index 0c7183e8b661..24e09092fda5 100644 --- a/tools/testing/selftests/mm/guard-regions.c +++ b/tools/testing/selftests/mm/guard-regions.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -2079,4 +2080,56 @@ TEST_F(guard_regions, pagemap) ASSERT_EQ(munmap(ptr, 10 * page_size), 0); } =20 +/* + * Assert that PAGEMAP_SCAN correctly reports guard region ranges. + */ +TEST_F(guard_regions, pagemap_scan) +{ + const unsigned long page_size =3D self->page_size; + struct page_region pm_regs[10]; + struct pm_scan_arg pm_scan_args =3D { + .size =3D sizeof(struct pm_scan_arg), + .category_anyof_mask =3D PAGE_IS_GUARD, + .return_mask =3D PAGE_IS_GUARD, + .vec =3D (long)&pm_regs, + .vec_len =3D ARRAY_SIZE(pm_regs), + }; + int proc_fd, i; + char *ptr; + + proc_fd =3D open("/proc/self/pagemap", O_RDONLY); + ASSERT_NE(proc_fd, -1); + + ptr =3D mmap_(self, variant, NULL, 10 * page_size, + PROT_READ | PROT_WRITE, 0, 0); + ASSERT_NE(ptr, MAP_FAILED); + + pm_scan_args.start =3D (long)ptr; + pm_scan_args.end =3D (long)ptr + 10 * page_size; + ASSERT_EQ(ioctl(proc_fd, PAGEMAP_SCAN, &pm_scan_args), 0); + ASSERT_EQ(pm_scan_args.walk_end, (long)ptr + 10 * page_size); + + /* Install a guard region in every other page. */ + for (i =3D 0; i < 10; i +=3D 2) { + char *ptr_p =3D &ptr[i * page_size]; + + ASSERT_EQ(syscall(__NR_madvise, ptr_p, page_size, MADV_GUARD_INSTALL), 0= ); + } + + ASSERT_EQ(ioctl(proc_fd, PAGEMAP_SCAN, &pm_scan_args), 5); + ASSERT_EQ(pm_scan_args.walk_end, (long)ptr + 10 * page_size); + + /* Re-read from pagemap, and assert guard regions are detected. */ + for (i =3D 0; i < 5; i++) { + long ptr_p =3D (long)&ptr[2 * i * page_size]; + + ASSERT_EQ(pm_regs[i].start, ptr_p); + ASSERT_EQ(pm_regs[i].end, ptr_p + page_size); + ASSERT_EQ(pm_regs[i].categories, PAGE_IS_GUARD); + } + + ASSERT_EQ(close(proc_fd), 0); + ASSERT_EQ(munmap(ptr, 10 * page_size), 0); +} + TEST_HARNESS_MAIN --=20 2.49.0.rc1.451.g8f38331e32-goog