Commit 3e9d80a8 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
Browse files

mm,fs: split dump_mapping() out from dump_page() 

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.

Link: https://lkml.kernel.org/r/20211121121056.2870061-1-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 26dca996

fs/inode.c

+49 −0
Original line number Diff line number Diff line
@@ -526,6 +526,55 @@ 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)

{

	/*

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -3152,6 +3152,7 @@ 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

mm/debug.c

+2 −50
Original line number Diff line number Diff line
@@ -112,56 +112,8 @@ 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: %pGp%s\n", type, &head->flags,