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authorSong Liu <songliubraving@fb.com>2019-09-24 01:38:03 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-25 01:54:11 +0300
commit09d91cda0e8207c1f14ee0d572f61a53dbcdaf85 (patch)
tree31686dc913d6904f0de79cecf644aa44e0cb49fc /mm
parent99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0 (diff)
downloadlinux-09d91cda0e8207c1f14ee0d572f61a53dbcdaf85.tar.xz
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@fb.com Signed-off-by: Song Liu <songliubraving@fb.com> Reported-by: kbuild test robot <lkp@intel.com> Acked-by: Rik van Riel <riel@surriel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hillf Danton <hdanton@sina.com> Cc: Hugh Dickins <hughd@google.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/filemap.c1
-rw-r--r--mm/khugepaged.c4
2 files changed, 4 insertions, 1 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 91fe3a08ca4a..1146fcfa3215 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 8607c77431b3..e89430ec5267 100644
--- a/mm/khugepaged.c
+++ b/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);