From nobody Wed Apr 8 09:41:47 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1AF9C38A2D for ; Mon, 24 Oct 2022 22:31:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230025AbiJXWbO (ORCPT ); Mon, 24 Oct 2022 18:31:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231538AbiJXWan (ORCPT ); Mon, 24 Oct 2022 18:30:43 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 453592D128C for ; Mon, 24 Oct 2022 13:53:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666644721; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vZ6z2mx7oNlRshrZTg5WSyqHxrl+GaeTDPKlsjXuMmM=; b=iGsbpUy3uxhqU/Jnbc1e2Sx71hGJA3WId1ZphmkDbuAlSTY2P2a4eE9E6gD4e7ts7k/psF mdKbDfLEiIGoeOtqjP93tdVfalf6dHOJT+5xYGgRwzQGwibI/S7tFYCIwq8578Ri5YKkkg moKDNPPTUrQQiVNxLDen9BKuXv1PbyM= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-230-j-0xwC3zPj2lRwzI6ZAH5w-1; Mon, 24 Oct 2022 16:48:37 -0400 X-MC-Unique: j-0xwC3zPj2lRwzI6ZAH5w-1 Received: by mail-qv1-f71.google.com with SMTP id 71-20020a0c804d000000b004b2fb260447so5928547qva.10 for ; Mon, 24 Oct 2022 13:48:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=vZ6z2mx7oNlRshrZTg5WSyqHxrl+GaeTDPKlsjXuMmM=; b=5Pg3xtCiooULxLhOORsXpMVj9dVfHVHvpi8dHXDo54+fz8jOqKAkZW5nYFzFmhnvHZ OpoUakchyok87L23Yop+HCQ4X94Hortt+nusQDtw20vafVleaeuipNt6or67oQd01fzZ dbA5z4CgSpb7ouaLNHdXgLyMlHCygNWl7WyP10pIkwwoXlCZ+yj/nSlosbGZCZgsto7q UZ1SmFxThwa2fYmLc+qXW0D/7ihHLCOU+0yMMJNJOf4s2shtWE3F1bWVUakoCdUPP6g+ RxQKRcXrI1RP7rDcHzI0tlWk0zcjj8rvmUfIYgJ8CYQzoJ05T4gYQwLvZmA6s/gkrMDe NNhw== X-Gm-Message-State: ACrzQf1rSvfYvHCvrfUInB/oznK6L/HDNY0X5CgkBt/iSlPHRMuSRIvW JPQXEULsfo5rfz2lD2+VunAdU2j2G+qd9u7Ll5Unk6CN7hj0VptKWV23Sa/viI4dlq+QkvJBq7j 16eonSJK+aKCOTfsm7bHcIJCynGfzb6aT7AzI8sFNvowH51WVPOyGynE/8ZwMJT6S1gt+0F10MQ == X-Received: by 2002:a05:6214:b6c:b0:4bb:6747:3089 with SMTP id ey12-20020a0562140b6c00b004bb67473089mr7896759qvb.41.1666644516193; Mon, 24 Oct 2022 13:48:36 -0700 (PDT) X-Google-Smtp-Source: AMsMyM6TOJBrQCGAvT7s3wRbvuxazhcJmkdpvIzFrO2mB8REtMPUwzf7bUiQBnGEcyrDxmWpKMjIKA== X-Received: by 2002:a05:6214:b6c:b0:4bb:6747:3089 with SMTP id ey12-20020a0562140b6c00b004bb67473089mr7896733qvb.41.1666644515915; Mon, 24 Oct 2022 13:48:35 -0700 (PDT) Received: from x1n.redhat.com (bras-base-aurron9127w-grc-46-70-31-27-79.dsl.bell.ca. [70.31.27.79]) by smtp.gmail.com with ESMTPSA id d13-20020ac8544d000000b0038d9555b580sm498531qtq.44.2022.10.24.13.48.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Oct 2022 13:48:35 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Huang Ying , peterx@redhat.com, Andrew Morton , HORIGUCHI NAOYA , Miaohe Lin , David Hildenbrand , Andrea Arcangeli Subject: [PATCH RFC 2/2] mm: Use pte markers for swap errors Date: Mon, 24 Oct 2022 16:48:30 -0400 Message-Id: <20221024204830.1342169-3-peterx@redhat.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221024204830.1342169-1-peterx@redhat.com> References: <20221024204830.1342169-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" PTE markers are ideal mechanism for things like SWP_SWAPIN_ERROR. Using a whole swap entry type for this purpose can be an overkill, especially if we already have PTE markers. Define a new bit for swapin error and replace it with pte markers. Then we can safely drop SWP_SWAPIN_ERROR and give one device slot back to swap. We used to have SWP_SWAPIN_ERROR taking the page pfn as part of the swap entry, but it's never used. Neither do I see how it can be useful because normally the swapin failure should not be caused by a bad page but bad swap device. Drop it alongside. Signed-off-by: Peter Xu Reviewed-by: Miaohe Lin --- include/linux/swap.h | 6 +----- include/linux/swapops.h | 26 ++++++++++++++------------ mm/memory.c | 6 ++++-- mm/shmem.c | 2 +- mm/swapfile.c | 2 +- 5 files changed, 21 insertions(+), 21 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 211aeca9bfa7..fec6647a289a 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -55,10 +55,6 @@ static inline int current_is_kswapd(void) * actions on faults. */ =20 -#define SWP_SWAPIN_ERROR_NUM 1 -#define SWP_SWAPIN_ERROR (MAX_SWAPFILES + SWP_HWPOISON_NUM + \ - SWP_MIGRATION_NUM + SWP_DEVICE_NUM + \ - SWP_PTE_MARKER_NUM) /* * PTE markers are used to persist information onto PTEs that otherwise * should be a none pte. As its name "PTE" hints, it should only be @@ -121,7 +117,7 @@ static inline int current_is_kswapd(void) #define MAX_SWAPFILES \ ((1 << MAX_SWAPFILES_SHIFT) - SWP_DEVICE_NUM - \ SWP_MIGRATION_NUM - SWP_HWPOISON_NUM - \ - SWP_PTE_MARKER_NUM - SWP_SWAPIN_ERROR_NUM) + SWP_PTE_MARKER_NUM) =20 /* * Magic header for a swap area. The first part of the union is diff --git a/include/linux/swapops.h b/include/linux/swapops.h index 41a6e7b23415..dd087b7287b0 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -162,16 +162,6 @@ static inline void *swp_to_radix_entry(swp_entry_t ent= ry) return xa_mk_value(entry.val); } =20 -static inline swp_entry_t make_swapin_error_entry(struct page *page) -{ - return swp_entry(SWP_SWAPIN_ERROR, page_to_pfn(page)); -} - -static inline int is_swapin_error_entry(swp_entry_t entry) -{ - return swp_type(entry) =3D=3D SWP_SWAPIN_ERROR; -} - #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) static inline swp_entry_t make_readable_device_private_entry(pgoff_t offse= t) { @@ -409,8 +399,9 @@ static inline bool is_migration_entry_dirty(swp_entry_t= entry) =20 typedef unsigned long pte_marker; =20 -#define PTE_MARKER_UFFD_WP BIT(0) -#define PTE_MARKER_MASK (PTE_MARKER_UFFD_WP) +#define PTE_MARKER_UFFD_WP BIT(0) +#define PTE_MARKER_SWAP_ERROR BIT(1) +#define PTE_MARKER_MASK (BIT(2) - 1) =20 static inline swp_entry_t make_pte_marker_entry(pte_marker marker) { @@ -437,6 +428,17 @@ static inline pte_t make_pte_marker(pte_marker marker) return swp_entry_to_pte(make_pte_marker_entry(marker)); } =20 +static inline swp_entry_t make_swapin_error_entry(void) +{ + return make_pte_marker_entry(PTE_MARKER_SWAP_ERROR); +} + +static inline int is_swapin_error_entry(swp_entry_t entry) +{ + return is_pte_marker_entry(entry) && + (pte_marker_get(entry) & PTE_MARKER_SWAP_ERROR); +} + /* * This is a special version to check pte_none() just to cover the case wh= en * the pte is a pte marker. It existed because in many cases the pte mark= er diff --git a/mm/memory.c b/mm/memory.c index 71114f05a68c..cf602c3854c3 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3705,6 +3705,10 @@ static vm_fault_t handle_pte_marker(struct vm_fault = *vmf) if (WARN_ON_ONCE(!marker)) return VM_FAULT_SIGBUS; =20 + /* Higher priority than uffd-wp when data corrupted */ + if (marker & PTE_MARKER_SWAP_ERROR) + return VM_FAULT_SIGBUS; + if (pte_marker_entry_uffd_wp(entry)) return pte_marker_handle_uffd_wp(vmf); =20 @@ -3764,8 +3768,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) put_page(vmf->page); } else if (is_hwpoison_entry(entry)) { ret =3D VM_FAULT_HWPOISON; - } else if (is_swapin_error_entry(entry)) { - ret =3D VM_FAULT_SIGBUS; } else if (is_pte_marker_entry(entry)) { ret =3D handle_pte_marker(vmf); } else { diff --git a/mm/shmem.c b/mm/shmem.c index c5f7a6668416..47dc595e98a3 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1682,7 +1682,7 @@ static void shmem_set_folio_swapin_error(struct inode= *inode, pgoff_t index, swp_entry_t swapin_error; void *old; =20 - swapin_error =3D make_swapin_error_entry(&folio->page); + swapin_error =3D make_swapin_error_entry(); old =3D xa_cmpxchg_irq(&mapping->i_pages, index, swp_to_radix_entry(swap), swp_to_radix_entry(swapin_error), 0); diff --git a/mm/swapfile.c b/mm/swapfile.c index 5fc1237a9f21..13f2569a6719 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1781,7 +1781,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_= t *pmd, pte_t pteval; =20 dec_mm_counter(vma->vm_mm, MM_SWAPENTS); - pteval =3D swp_entry_to_pte(make_swapin_error_entry(page)); + pteval =3D swp_entry_to_pte(make_swapin_error_entry()); set_pte_at(vma->vm_mm, addr, pte, pteval); swap_free(entry); ret =3D 0; --=20 2.37.3