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authorRongwei Wang <rongwei.wang@linux.alibaba.com>2021-11-05 13:43:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-11-06 13:30:41 -0700
commit8468e937df1f31411d1e127fa38db064af051fe5 (patch)
treebf92936b01daff89a65228c810bf68a984d3f9eb /fs/open.c
parent55fc0d91746759c71bc165bba62a2db64ac98e35 (diff)
mm, thp: fix incorrect unmap behavior for private pages
When truncating pagecache on file THP, the private pages of a process should not be unmapped mapping. This incorrect behavior on a dynamic shared libraries which will cause related processes to happen core dump. A simple test for a DSO (Prerequisite is the DSO mapped in file THP): int main(int argc, char *argv[]) { int fd; fd = open(argv[1], O_WRONLY); if (fd < 0) { perror("open"); } close(fd); return 0; } The test only to open a target DSO, and do nothing. But this operation will lead one or more process to happen core dump. This patch mainly to fix this bug. Link: https://lkml.kernel.org/r/20211025092134.18562-3-rongwei.wang@linux.alibaba.com Fixes: eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs") Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com> Tested-by: Xu Yu <xuyu@linux.alibaba.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Song Liu <song@kernel.org> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Collin Fijalkovich <cfijalkovich@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/open.c')
-rw-r--r--fs/open.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/fs/open.c b/fs/open.c
index 9ec3cfca3b1a..e0df1536eb69 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -857,8 +857,17 @@ static int do_dentry_open(struct file *f,
*/
smp_mb();
if (filemap_nr_thps(inode->i_mapping)) {
+ struct address_space *mapping = inode->i_mapping;
+
filemap_invalidate_lock(inode->i_mapping);
- truncate_pagecache(inode, 0);
+ /*
+ * unmap_mapping_range just need to be called once
+ * here, because the private pages is not need to be
+ * unmapped mapping (e.g. data segment of dynamic
+ * shared libraries here).
+ */
+ unmap_mapping_range(mapping, 0, 0, 0);
+ truncate_inode_pages(mapping, 0);
filemap_invalidate_unlock(inode->i_mapping);
}
}