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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 955FEC4332F for ; Fri, 14 Jan 2022 22:05:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 24F2F6B00DB; Fri, 14 Jan 2022 17:05:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1FF8D6B00DD; Fri, 14 Jan 2022 17:05:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 079F06B00DE; Fri, 14 Jan 2022 17:05:24 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0146.hostedemail.com [216.40.44.146]) by kanga.kvack.org (Postfix) with ESMTP id E62AC6B00DB for ; Fri, 14 Jan 2022 17:05:23 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id AA1AD80F9B3E for ; Fri, 14 Jan 2022 22:05:23 +0000 (UTC) X-FDA: 79030274526.18.CC105B1 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf20.hostedemail.com (Postfix) with ESMTP id E4BFD1C0002 for ; Fri, 14 Jan 2022 22:05:22 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E26A5B825F5; Fri, 14 Jan 2022 22:05:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34B6DC36AEC; Fri, 14 Jan 2022 22:05:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1642197920; bh=8AIMNW2kktylIwIkCjAs27utNwB1FH1LY8ztkjD6O1I=; h=Date:From:To:Subject:In-Reply-To:From; b=QTN/Dn6uRPJV7k5hCQvVQ/92//NZshNWi1UEJvyfiloDkfkZvsRKpjNys7RMZ79Ed 8qht9a2kNlhrMPgOZhou+6fQ6yY/yEtsa5Gxh3C4hpxNeTaU60xv0xCzSKLIFw2WBh rHV18EWq9CTmZAgjlmDfNf8EIY2Wlg//qAZ9DmO0= Date: Fri, 14 Jan 2022 14:05:19 -0800 From: Andrew Morton To: ajaygargnsit@gmail.com, akpm@linux-foundation.org, andy.lavr@gmail.com, arnd@arndb.de, hughd@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, naoya.horiguchi@nec.com, osalvador@suse.de, peterx@redhat.com, shy828301@gmail.com, songmuchun@bytedance.com, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 045/146] mm: shmem: don't truncate page if memory failure happens Message-ID: <20220114220519.M1fWj4WeI%akpm@linux-foundation.org> In-Reply-To: <20220114140222.6b14f0061194d3200000c52d@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: E4BFD1C0002 X-Stat-Signature: 3t6mnr5th8gedxuxt7t3met1i9eqpy5b Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="QTN/Dn6u"; dmarc=none; spf=pass (imf20.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam08 X-HE-Tag: 1642197922-206010 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: From: Yang Shi Subject: mm: shmem: don't truncate page if memory failure happens The current behavior of memory failure is to truncate the page cache regardless of dirty or clean. If the page is dirty the later access will get the obsolete data from disk without any notification to the users. This may cause silent data loss. It is even worse for shmem since shmem is in-memory filesystem, truncating page cache means discarding data blocks. The later read would return all zero. The right approach is to keep the corrupted page in page cache, any later access would return error for syscalls or SIGBUS for page fault, until the file is truncated, hole punched or removed. The regular storage backed filesystems would be more complicated so this patch is focused on shmem. This also unblock the support for soft offlining shmem THP. [akpm@linux-foundation.org: coding style fixes] [arnd@arndb.de: fix uninitialized variable use in me_pagecache_clean()] Link: https://lkml.kernel.org/r/20211022064748.4173718-1-arnd@kernel.org [Fix invalid pointer dereference in shmem_read_mapping_page_gfp() with a slight different implementation from what Ajay Garg and Muchun Song proposed and reworked the error handling of shmem_write_begin() suggested by Linus] Link: https://lore.kernel.org/linux-mm/20211111084617.6746-1-ajaygargnsit@gmail.com/ Link: https://lkml.kernel.org/r/20211020210755.23964-6-shy828301@gmail.com Link: https://lkml.kernel.org/r/20211116193247.21102-1-shy828301@gmail.com Signed-off-by: Yang Shi Signed-off-by: Arnd Bergmann Cc: Hugh Dickins Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Naoya Horiguchi Cc: Oscar Salvador Cc: Peter Xu Cc: Ajay Garg Cc: Muchun Song Cc: Andy Lavr Signed-off-by: Andrew Morton --- mm/memory-failure.c | 14 +++++++++-- mm/shmem.c | 51 +++++++++++++++++++++++++++++++++++++----- mm/userfaultfd.c | 5 ++++ 3 files changed, 61 insertions(+), 9 deletions(-) --- a/mm/memory-failure.c~mm-shmem-dont-truncate-page-if-memory-failure-happens +++ a/mm/memory-failure.c @@ -58,6 +58,7 @@ #include #include #include +#include #include "internal.h" #include "ras/ras_event.h" @@ -867,6 +868,7 @@ static int me_pagecache_clean(struct pag { int ret; struct address_space *mapping; + bool extra_pins; delete_from_lru_cache(p); @@ -896,17 +898,23 @@ static int me_pagecache_clean(struct pag } /* + * The shmem page is kept in page cache instead of truncating + * so is expected to have an extra refcount after error-handling. + */ + extra_pins = shmem_mapping(mapping); + + /* * Truncation is a bit tricky. Enable it per file system for now. * * Open: to take i_rwsem or not for this? Right now we don't. */ ret = truncate_error_page(p, page_to_pfn(p), mapping); + if (has_extra_refcount(ps, p, extra_pins)) + ret = MF_FAILED; + out: unlock_page(p); - if (has_extra_refcount(ps, p, false)) - ret = MF_FAILED; - return ret; } --- a/mm/shmem.c~mm-shmem-dont-truncate-page-if-memory-failure-happens +++ a/mm/shmem.c @@ -2457,6 +2457,7 @@ shmem_write_begin(struct file *file, str struct inode *inode = mapping->host; struct shmem_inode_info *info = SHMEM_I(inode); pgoff_t index = pos >> PAGE_SHIFT; + int ret = 0; /* i_rwsem is held by caller */ if (unlikely(info->seals & (F_SEAL_GROW | @@ -2467,7 +2468,19 @@ shmem_write_begin(struct file *file, str return -EPERM; } - return shmem_getpage(inode, index, pagep, SGP_WRITE); + ret = shmem_getpage(inode, index, pagep, SGP_WRITE); + + if (ret) + return ret; + + if (PageHWPoison(*pagep)) { + unlock_page(*pagep); + put_page(*pagep); + *pagep = NULL; + return -EIO; + } + + return 0; } static int @@ -2554,6 +2567,12 @@ static ssize_t shmem_file_read_iter(stru if (sgp == SGP_CACHE) set_page_dirty(page); unlock_page(page); + + if (PageHWPoison(page)) { + put_page(page); + error = -EIO; + break; + } } /* @@ -3093,7 +3112,8 @@ static const char *shmem_get_link(struct page = find_get_page(inode->i_mapping, 0); if (!page) return ERR_PTR(-ECHILD); - if (!PageUptodate(page)) { + if (PageHWPoison(page) || + !PageUptodate(page)) { put_page(page); return ERR_PTR(-ECHILD); } @@ -3101,6 +3121,13 @@ static const char *shmem_get_link(struct error = shmem_getpage(inode, 0, &page, SGP_READ); if (error) return ERR_PTR(error); + if (!page) + return ERR_PTR(-ECHILD); + if (PageHWPoison(page)) { + unlock_page(page); + put_page(page); + return ERR_PTR(-ECHILD); + } unlock_page(page); } set_delayed_call(done, shmem_put_link, page); @@ -3751,6 +3778,13 @@ static void shmem_destroy_inodecache(voi kmem_cache_destroy(shmem_inode_cachep); } +/* Keep the page in page cache instead of truncating it */ +static int shmem_error_remove_page(struct address_space *mapping, + struct page *page) +{ + return 0; +} + const struct address_space_operations shmem_aops = { .writepage = shmem_writepage, .set_page_dirty = __set_page_dirty_no_writeback, @@ -3761,7 +3795,7 @@ const struct address_space_operations sh #ifdef CONFIG_MIGRATION .migratepage = migrate_page, #endif - .error_remove_page = generic_error_remove_page, + .error_remove_page = shmem_error_remove_page, }; EXPORT_SYMBOL(shmem_aops); @@ -4169,9 +4203,14 @@ struct page *shmem_read_mapping_page_gfp error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL, NULL, NULL); if (error) - page = ERR_PTR(error); - else - unlock_page(page); + return ERR_PTR(error); + + unlock_page(page); + if (PageHWPoison(page)) { + put_page(page); + return ERR_PTR(-EIO); + } + return page; #else /* --- a/mm/userfaultfd.c~mm-shmem-dont-truncate-page-if-memory-failure-happens +++ a/mm/userfaultfd.c @@ -232,6 +232,11 @@ static int mcontinue_atomic_pte(struct m goto out; } + if (PageHWPoison(page)) { + ret = -EIO; + goto out_release; + } + ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, page, false, wp_copy); if (ret) _