From: Mike Kravetz <mike.kravetz@oracle.com> mainline inclusion from mainline-v5.9-rc1 commit 15568299b7d9988063afce60731df605ab236e2a category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/9351 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- syzbot found issues with having hugetlbfs on a union/overlay as reported in [1]. Due to the limitations (no write) and special functionality of hugetlbfs, it does not work well in filesystem stacking. There are no know use cases for hugetlbfs stacking. Rather than making modifications to get hugetlbfs working in such environments, simply prevent stacking. [1] https://lore.kernel.org/linux-mm/000000000000b4684e05a2968ca6@google.com/ Reported-by: syzbot+d6ec23007e951dadf3de@syzkaller.appspotmail.com Suggested-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Miklos Szeredi <mszeredi@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Colin Walters <walters@verbum.org> Link: http://lkml.kernel.org/r/80f869aa-810d-ef6c-8888-b46cee135907@oracle.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Conflicts: fs/hugetlbfs/inode.c [Fix context conflicts.] Signed-off-by: Zeng Heng <zengheng4@huawei.com> --- fs/hugetlbfs/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 39a4d1f820d2..6825c870d0b5 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -1452,6 +1452,12 @@ hugetlbfs_fill_super(struct super_block *sb, void *data, int silent) sb->s_magic = HUGETLBFS_MAGIC; sb->s_op = &hugetlbfs_ops; sb->s_time_gran = 1; + + /* + * Due to the special and limited functionality of hugetlbfs, it does + * not work well as a stacking filesystem. + */ + sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH; sb->s_root = d_make_root(hugetlbfs_get_root(sb, &config)); if (!sb->s_root) goto out_free; -- 2.43.0