On Sun 21-11-21 12:10:56, Matthew Wilcox wrote:
> dump_mapping() is a big chunk of dump_page(), and it'd be handy to be
> able to call it when we don't have a struct page. Split it out and move
> it to fs/inode.c. Take the opportunity to simplify some of the debug
> messages a little.
Makes sense. I haven't checked the head files inclusion side of this but
I suspect mm heads do include uaccess.h. Not sure inode.c does as well.
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> fs/inode.c | 49 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/fs.h | 1 +
> mm/debug.c | 52 ++--------------------------------------------
> 3 files changed, 52 insertions(+), 50 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index bdfbd5962f2b..67758b2b702f 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -522,6 +522,55 @@ void __remove_inode_hash(struct inode *inode)
> }
> EXPORT_SYMBOL(__remove_inode_hash);
>
> +void dump_mapping(const struct address_space *mapping)
> +{
> + struct inode *host;
> + const struct address_space_operations *a_ops;
> + struct hlist_node *dentry_first;
> + struct dentry *dentry_ptr;
> + struct dentry dentry;
> + unsigned long ino;
> +
> + /*
> + * If mapping is an invalid pointer, we don't want to crash
> + * accessing it, so probe everything depending on it carefully.
> + */
> + if (get_kernel_nofault(host, &mapping->host) ||
> + get_kernel_nofault(a_ops, &mapping->a_ops)) {
> + pr_warn("invalid mapping:%px\n", mapping);
> + return;
> + }
> +
> + if (!host) {
> + pr_warn("aops:%ps\n", a_ops);
> + return;
> + }
> +
> + if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
> + get_kernel_nofault(ino, &host->i_ino)) {
> + pr_warn("aops:%ps invalid inode:%px\n", a_ops, host);
> + return;
> + }
> +
> + if (!dentry_first) {
> + pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
> + return;
> + }
> +
> + dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
> + if (get_kernel_nofault(dentry, dentry_ptr)) {
> + pr_warn("aops:%ps ino:%lx invalid dentry:%px\n",
> + a_ops, ino, dentry_ptr);
> + return;
> + }
> +
> + /*
> + * if dentry is corrupted, the %pd handler may still crash,
> + * but it's unlikely that we reach here with a corrupt mapping
> + */
> + pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n", a_ops, ino, &dentry);
> +}
> +
> void clear_inode(struct inode *inode)
> {
> /*
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index d6a4eb6cf825..acaad2b0d5b9 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -3149,6 +3149,7 @@ extern void unlock_new_inode(struct inode *);
> extern void discard_new_inode(struct inode *);
> extern unsigned int get_next_ino(void);
> extern void evict_inodes(struct super_block *sb);
> +void dump_mapping(const struct address_space *);
>
> /*
> * Userspace may rely on the the inode number being non-zero. For example, glibc
> diff --git a/mm/debug.c b/mm/debug.c
> index fae0f81ad831..b3ebfab21cb3 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -110,56 +110,8 @@ static void __dump_page(struct page *page)
> type = "ksm ";
> else if (PageAnon(page))
> type = "anon ";
> - else if (mapping) {
> - struct inode *host;
> - const struct address_space_operations *a_ops;
> - struct hlist_node *dentry_first;
> - struct dentry *dentry_ptr;
> - struct dentry dentry;
> - unsigned long ino;
> -
> - /*
> - * mapping can be invalid pointer and we don't want to crash
> - * accessing it, so probe everything depending on it carefully
> - */
> - if (get_kernel_nofault(host, &mapping->host) ||
> - get_kernel_nofault(a_ops, &mapping->a_ops)) {
> - pr_warn("failed to read mapping contents, not a valid kernel address?\n");
> - goto out_mapping;
> - }
> -
> - if (!host) {
> - pr_warn("aops:%ps\n", a_ops);
> - goto out_mapping;
> - }
> -
> - if (get_kernel_nofault(dentry_first, &host->i_dentry.first) ||
> - get_kernel_nofault(ino, &host->i_ino)) {
> - pr_warn("aops:%ps with invalid host inode %px\n",
> - a_ops, host);
> - goto out_mapping;
> - }
> -
> - if (!dentry_first) {
> - pr_warn("aops:%ps ino:%lx\n", a_ops, ino);
> - goto out_mapping;
> - }
> -
> - dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);
> - if (get_kernel_nofault(dentry, dentry_ptr)) {
> - pr_warn("aops:%ps ino:%lx with invalid dentry %px\n",
> - a_ops, ino, dentry_ptr);
> - } else {
> - /*
> - * if dentry is corrupted, the %pd handler may still
> - * crash, but it's unlikely that we reach here with a
> - * corrupted struct page
> - */
> - pr_warn("aops:%ps ino:%lx dentry name:\"%pd\"\n",
> - a_ops, ino, &dentry);
> - }
> - }
> -out_mapping:
> + else if (mapping)
> + dump_mapping(mapping);
> BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1);
>
> pr_warn("%sflags: %#lx(%pGp)%s\n", type, head->flags, &head->flags,
> --
> 2.33.0
--
Michal Hocko
SUSE Labs
