The patch titled
Subject: mm,thp: avoid writes to file with THP in pagecache
has been added to the -mm tree. Its filename is
mmthp-avoid-writes-to-file-with-thp-in-pagecache.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mmthp-avoid-writes-to-file-with-thp-in-pagecache.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mmthp-avoid-writes-to-file-with-thp-in-pagecache.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Song Liu <songliubraving@xxxxxx>
Subject: mm,thp: avoid writes to file with THP in pagecache
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_dentry_open(), if the file is open for write and
nr_thps is non-zero, we drop page cache for the whole file.
Link: http://lkml.kernel.org/r/20190801184244.3169074-8-songliubraving@xxxxxx
Signed-off-by: Song Liu <songliubraving@xxxxxx>
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/inode.c | 3 +++
fs/open.c | 8 ++++++++
include/linux/fs.h | 32 ++++++++++++++++++++++++++++++++
mm/filemap.c | 1 +
mm/khugepaged.c | 4 +++-
5 files changed, 47 insertions(+), 1 deletion(-)
--- a/fs/inode.c~mmthp-avoid-writes-to-file-with-thp-in-pagecache
+++ a/fs/inode.c
@@ -181,6 +181,9 @@ int inode_init_always(struct super_block
mapping->flags = 0;
mapping->wb_err = 0;
atomic_set(&mapping->i_mmap_writable, 0);
+#ifdef CONFIG_READ_ONLY_THP_FOR_FS
+ atomic_set(&mapping->nr_thps, 0);
+#endif
mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
mapping->private_data = NULL;
mapping->writeback_index = 0;
--- a/fs/open.c~mmthp-avoid-writes-to-file-with-thp-in-pagecache
+++ a/fs/open.c
@@ -818,6 +818,14 @@ static int do_dentry_open(struct file *f
if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
return -EINVAL;
}
+
+ /*
+ * XXX: Huge page cache doesn't support writing yet. Drop all page
+ * cache for this file before processing writes.
+ */
+ if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
+ truncate_pagecache(inode, 0);
+
return 0;
cleanup_all:
--- a/include/linux/fs.h~mmthp-avoid-writes-to-file-with-thp-in-pagecache
+++ a/include/linux/fs.h
@@ -429,6 +429,7 @@ int pagecache_write_end(struct file *, s
* @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.
@@ -446,6 +447,10 @@ 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;
@@ -2798,6 +2803,33 @@ static inline errseq_t filemap_sample_wb
return errseq_sample(&mapping->wb_err);
}
+static inline int filemap_nr_thps(struct address_space *mapping)
+{
+#ifdef CONFIG_READ_ONLY_THP_FOR_FS
+ return atomic_read(&mapping->nr_thps);
+#else
+ return 0;
+#endif
+}
+
+static inline void filemap_nr_thps_inc(struct address_space *mapping)
+{
+#ifdef CONFIG_READ_ONLY_THP_FOR_FS
+ atomic_inc(&mapping->nr_thps);
+#else
+ WARN_ON_ONCE(1);
+#endif
+}
+
+static inline void filemap_nr_thps_dec(struct address_space *mapping)
+{
+#ifdef CONFIG_READ_ONLY_THP_FOR_FS
+ atomic_dec(&mapping->nr_thps);
+#else
+ WARN_ON_ONCE(1);
+#endif
+}
+
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);
--- a/mm/filemap.c~mmthp-avoid-writes-to-file-with-thp-in-pagecache
+++ a/mm/filemap.c
@@ -205,6 +205,7 @@ static void unaccount_page_cache_page(st
__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);
}
/*
--- a/mm/khugepaged.c~mmthp-avoid-writes-to-file-with-thp-in-pagecache
+++ a/mm/khugepaged.c
@@ -1514,8 +1514,10 @@ out_unlock:
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);
_
Patches currently in -mm which might be from songliubraving@xxxxxx are
filemap-check-compound_headpage-mapping-in-filemap_fault.patch
filemap-check-compound_headpage-mapping-in-pagecache_get_page.patch
filemap-update-offset-check-in-filemap_fault.patch
mmthp-stats-for-file-backed-thp.patch
khugepaged-rename-collapse_shmem-and-khugepaged_scan_shmem.patch
mmthp-add-read-only-thp-support-for-non-shmem-fs.patch
mmthp-avoid-writes-to-file-with-thp-in-pagecache.patch
mm-move-memcmp_pages-and-pages_identical.patch
uprobe-use-original-page-when-all-uprobes-are-removed.patch
mm-thp-introduce-foll_split_pmd.patch
uprobe-use-foll_split_pmd-instead-of-foll_split.patch
khugepaged-enable-collapse-pmd-for-pte-mapped-thp.patch
uprobe-collapse-thp-pmd-after-removing-all-uprobes.patch
