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[67.231.153.30]) by mx.google.com with ESMTPS id h20si4259774ywa.373.2019.06.24.15.30.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Jun 2019 15:30:17 -0700 (PDT) Received-SPF: pass (google.com: domain of prvs=1078cbd532=songliubraving@fb.com designates 67.231.153.30 as permitted sender) client-ip=67.231.153.30; Authentication-Results: mx.google.com; dkim=pass header.i=@fb.com header.s=facebook header.b=bDtECx7J; spf=pass (google.com: domain of prvs=1078cbd532=songliubraving@fb.com designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=1078cbd532=songliubraving@fb.com"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=fb.com Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5OMIE4t000694 for ; Mon, 24 Jun 2019 15:30:17 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=1YmphlJ3H8jOCDJ7k4G2S7xvfsjoBsLcepmZ6MADQ8Y=; b=bDtECx7JjGTraAQgcG+LiSc0bC+DOB+jM2yn4IYkK2W7vzJreSCkFUik5nANicKPctGH GEVwBJchObVFymR3+HxGxfiY0ESoyufbZdV3sAYjbm4gpcIuIgq1f+GyrXDCCZutciMc 81z1y+YcZ+IWajUeJ1ItDgGTxIa7xRIEgMg= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 2tb6j2g6a8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 24 Jun 2019 15:30:16 -0700 Received: from mx-out.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Mon, 24 Jun 2019 15:30:16 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id E384862E206E; Mon, 24 Jun 2019 15:30:11 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig006.ftw2.facebook.com To: , , CC: , , , , , , Song Liu Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v8 6/6] mm,thp: avoid writes to file with THP in pagecache Date: Mon, 24 Jun 2019 15:29:51 -0700 Message-ID: <20190624222951.37076-7-songliubraving@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190624222951.37076-1-songliubraving@fb.com> References: <20190624222951.37076-1-songliubraving@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-24_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=801 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906240176 X-FB-Internal: deliver 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: X-Virus-Scanned: ClamAV using ClamSMTP In previous patch, an application could put part of its text section in THP via madvise(). These THPs will be protected from writes when the application is still running (TXTBSY). However, after the application exits, the file is available for writes. This patch avoids writes to file THP by dropping page cache for the file when the file is open for write. A new counter nr_thps is added to struct address_space. In do_last(), if the file is open for write and nr_thps is non-zero, we drop page cache for the whole file. Reported-by: kbuild test robot Signed-off-by: Song Liu --- fs/inode.c | 2 ++ fs/namei.c | 23 ++++++++++++++++++++++- include/linux/fs.h | 28 ++++++++++++++++++++++++++++ mm/filemap.c | 1 + mm/khugepaged.c | 4 +++- 5 files changed, 56 insertions(+), 2 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index df6542ec3b88..7f27a5fd147b 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -181,6 +181,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode) mapping->flags = 0; mapping->wb_err = 0; atomic_set(&mapping->i_mmap_writable, 0); + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) + atomic_set(&mapping->nr_thps, 0); mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE); mapping->private_data = NULL; mapping->writeback_index = 0; diff --git a/fs/namei.c b/fs/namei.c index 20831c2fbb34..3d95e94029cc 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3249,6 +3249,23 @@ static int lookup_open(struct nameidata *nd, struct path *path, return error; } +/* + * The file is open for write, so it is not mmapped with VM_DENYWRITE. If + * it still has THP in page cache, drop the whole file from pagecache + * before processing writes. This helps us avoid handling write back of + * THP for now. + */ +static inline void release_file_thp(struct file *file) +{ + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) { + struct inode *inode = file_inode(file); + + if (inode_is_open_for_write(inode) && + filemap_nr_thps(inode->i_mapping)) + truncate_pagecache(inode, 0); + } +} + /* * Handle the last step of open() */ @@ -3418,7 +3435,11 @@ static int do_last(struct nameidata *nd, goto out; opened: error = ima_file_check(file, op->acc_mode); - if (!error && will_truncate) + if (error) + goto out; + + release_file_thp(file); + if (will_truncate) error = handle_truncate(file); out: if (unlikely(error > 0)) { diff --git a/include/linux/fs.h b/include/linux/fs.h index f7fdfe93e25d..20443d63692e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -427,6 +427,7 @@ int pagecache_write_end(struct file *, struct address_space *mapping, * @i_pages: Cached pages. * @gfp_mask: Memory allocation flags to use for allocating pages. * @i_mmap_writable: Number of VM_SHARED mappings. + * @nr_thps: Number of THPs in the pagecache (non-shmem only). * @i_mmap: Tree of private and shared mappings. * @i_mmap_rwsem: Protects @i_mmap and @i_mmap_writable. * @nrpages: Number of page entries, protected by the i_pages lock. @@ -444,6 +445,10 @@ struct address_space { struct xarray i_pages; gfp_t gfp_mask; atomic_t i_mmap_writable; +#ifdef CONFIG_READ_ONLY_THP_FOR_FS + /* number of thp, only for non-shmem files */ + atomic_t nr_thps; +#endif struct rb_root_cached i_mmap; struct rw_semaphore i_mmap_rwsem; unsigned long nrpages; @@ -2790,6 +2795,29 @@ static inline errseq_t filemap_sample_wb_err(struct address_space *mapping) return errseq_sample(&mapping->wb_err); } +static inline int filemap_nr_thps(struct address_space *mapping) +{ + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) + return atomic_read(&mapping->nr_thps); + return 0; +} + +static inline void filemap_nr_thps_inc(struct address_space *mapping) +{ + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) + atomic_inc(&mapping->nr_thps); + else + WARN_ON_ONCE(1); +} + +static inline void filemap_nr_thps_dec(struct address_space *mapping) +{ + if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS)) + atomic_dec(&mapping->nr_thps); + else + WARN_ON_ONCE(1); +} + extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync); extern int vfs_fsync(struct file *file, int datasync); diff --git a/mm/filemap.c b/mm/filemap.c index e79ceccdc6df..a8e86c136381 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -205,6 +205,7 @@ static void unaccount_page_cache_page(struct address_space *mapping, __dec_node_page_state(page, NR_SHMEM_THPS); } else if (PageTransHuge(page)) { __dec_node_page_state(page, NR_FILE_THPS); + filemap_nr_thps_dec(mapping); } /* diff --git a/mm/khugepaged.c b/mm/khugepaged.c index acbbbeaa083c..0bbc6be51197 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1503,8 +1503,10 @@ static void collapse_file(struct mm_struct *mm, if (is_shmem) __inc_node_page_state(new_page, NR_SHMEM_THPS); - else + else { __inc_node_page_state(new_page, NR_FILE_THPS); + filemap_nr_thps_inc(mapping); + } if (nr_none) { struct zone *zone = page_zone(new_page);