From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F1C0A84A3F; Tue, 14 May 2024 10:56:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715684204; cv=none; b=cFrCud0BekvXmB8I7aEC/kIEbexRNbGlZxFwFdseTMJSp9vGBmI3gJ6eqcuF4apstdGeAgfvzwmUWrvlUOv+X1N8rJxo7Ct1KQGHNB6p7aPw/dwRuCm6vzv6bKkEfbZStGkf/KJIS+Xr/nDQv9PhCZxsBiD3xxOH9MIr5dM32zM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715684204; c=relaxed/simple; bh=wRdhn/dQid05s7zg3Z1p/b5D6muU2EV/7M7xs3VXkLc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dtfD2OciAGDGrz9y7+JGSNk34issLyKifFw4bGWh1EQmOri2UwnDYl7duc5lOvr+ttWPqVfkJW/JhLitCnpe0+hVtDbyPgriEL5NhooM/EO5Isv5pB81Y2LhCZeBsWKrKYnJxK2XeNgXoQmf/wEn81B6zTQYp3lKsGTg4bY+NBM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GTIUbqn9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="GTIUbqn9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5DBA3C2BD10; Tue, 14 May 2024 10:56:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1715684203; bh=wRdhn/dQid05s7zg3Z1p/b5D6muU2EV/7M7xs3VXkLc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GTIUbqn9o0Eq9jLriLi8TA++Wr6Yn2mid1Sy5vhDSH8JSKrW8O0FdUr/lTdy9OE73 qtmM9rN6HPk0GE8TxddAw55sB7iPf1EzMYkn9jCQRL8MoSyaoY9k0ipjJDWJKvOtcM 478PZGYmpFRRe4NcrJp+VrX5geKMmQYZUI0GsET0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ryan Roberts , David Hildenbrand , Muhammad Usama Anjum , Peter Xu , Andrew Morton Subject: [PATCH 6.8 318/336] fs/proc/task_mmu: fix uffd-wp confusion in pagemap_scan_pmd_entry() Date: Tue, 14 May 2024 12:18:42 +0200 Message-ID: <20240514101050.628271078@linuxfoundation.org> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240514101038.595152603@linuxfoundation.org> References: <20240514101038.595152603@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ryan Roberts commit 2c7ad9a590d1a99ec59c7d90cef41e2b296944c4 upstream. pagemap_scan_pmd_entry() checks if uffd-wp is set on each pte to avoid unnecessary if set. However it was previously checking with `pte_uffd_wp(ptep_get(pte))` without first confirming that the pte was present. It is only valid to call pte_uffd_wp() for present ptes. For swap ptes, pte_swp_uffd_wp() must be called because the uffd-wp bit may be kept in a different position, depending on the arch. This was leading to test failures in the pagemap_ioctl mm selftest, when bringing up uffd-wp support on arm64 due to incorrectly interpretting the uffd-wp status of migration entries. Let's fix this by using the correct check based on pte_present(). While we are at it, let's pass the pte to make_uffd_wp_pte() to avoid the pointless extra ptep_get() which can't be optimized out due to READ_ONCE() on many arches. Link: https://lkml.kernel.org/r/20240429114104.182890-1-ryan.roberts@arm.com Fixes: 12f6b01a0bcb ("fs/proc/task_mmu: add fast paths to get/clear PAGE_IS_WRITTEN flag") Closes: https://lore.kernel.org/linux-arm-kernel/ZiuyGXt0XWwRgFh9@x1n/ Signed-off-by: Ryan Roberts Acked-by: David Hildenbrand Reviewed-by: Muhammad Usama Anjum Tested-by: Muhammad Usama Anjum Cc: Peter Xu Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/proc/task_mmu.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1818,10 +1818,8 @@ static unsigned long pagemap_page_catego } static void make_uffd_wp_pte(struct vm_area_struct *vma, - unsigned long addr, pte_t *pte) + unsigned long addr, pte_t *pte, pte_t ptent) { - pte_t ptent = ptep_get(pte); - if (pte_present(ptent)) { pte_t old_pte; @@ -2176,9 +2174,12 @@ static int pagemap_scan_pmd_entry(pmd_t if ((p->arg.flags & PM_SCAN_WP_MATCHING) && !p->vec_out) { /* Fast path for performing exclusive WP */ for (addr = start; addr != end; pte++, addr += PAGE_SIZE) { - if (pte_uffd_wp(ptep_get(pte))) + pte_t ptent = ptep_get(pte); + + if ((pte_present(ptent) && pte_uffd_wp(ptent)) || + pte_swp_uffd_wp_any(ptent)) continue; - make_uffd_wp_pte(vma, addr, pte); + make_uffd_wp_pte(vma, addr, pte, ptent); if (!flush_end) start = addr; flush_end = addr + PAGE_SIZE; @@ -2191,8 +2192,10 @@ static int pagemap_scan_pmd_entry(pmd_t p->arg.return_mask == PAGE_IS_WRITTEN) { for (addr = start; addr < end; pte++, addr += PAGE_SIZE) { unsigned long next = addr + PAGE_SIZE; + pte_t ptent = ptep_get(pte); - if (pte_uffd_wp(ptep_get(pte))) + if ((pte_present(ptent) && pte_uffd_wp(ptent)) || + pte_swp_uffd_wp_any(ptent)) continue; ret = pagemap_scan_output(p->cur_vma_category | PAGE_IS_WRITTEN, p, addr, &next); @@ -2200,7 +2203,7 @@ static int pagemap_scan_pmd_entry(pmd_t break; if (~p->arg.flags & PM_SCAN_WP_MATCHING) continue; - make_uffd_wp_pte(vma, addr, pte); + make_uffd_wp_pte(vma, addr, pte, ptent); if (!flush_end) start = addr; flush_end = next; @@ -2209,8 +2212,9 @@ static int pagemap_scan_pmd_entry(pmd_t } for (addr = start; addr != end; pte++, addr += PAGE_SIZE) { + pte_t ptent = ptep_get(pte); unsigned long categories = p->cur_vma_category | - pagemap_page_category(p, vma, addr, ptep_get(pte)); + pagemap_page_category(p, vma, addr, ptent); unsigned long next = addr + PAGE_SIZE; if (!pagemap_scan_is_interesting_page(categories, p)) @@ -2225,7 +2229,7 @@ static int pagemap_scan_pmd_entry(pmd_t if (~categories & PAGE_IS_WRITTEN) continue; - make_uffd_wp_pte(vma, addr, pte); + make_uffd_wp_pte(vma, addr, pte, ptent); if (!flush_end) start = addr; flush_end = next;