Commit 9ad38265 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Linus Torvalds
Browse files

mm/debug: switch dump_page to get_kernel_nofault 



This is simpler to use than copy_from_kernel_nofault().  Also make some of
the related error messages less verbose.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarMike Rapoport <rppt@linux.ibm.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: William Kucharski <william.kucharski@oracle.com>
Link: http://lkml.kernel.org/r/20200709202117.7216-5-willy@infradead.org


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0b93d59e

mm/debug.c

+16 −20
Original line number Diff line number Diff line
@@ -115,54 +115,50 @@ void __dump_page(struct page *page, const char *reason) 
	else if (PageAnon(page))

		type = "anon ";

	else if (mapping) {

		const struct inode *host;

		struct inode *host;

		const struct address_space_operations *a_ops;

		const struct hlist_node *dentry_first;

		const struct dentry *dentry_ptr;

		struct hlist_node *dentry_first;

		struct dentry *dentry_ptr;

		struct dentry dentry;



		/*

		 * mapping can be invalid pointer and we don't want to crash

		 * accessing it, so probe everything depending on it carefully

		 */

		if (copy_from_kernel_nofault(&host, &mapping->host,

					sizeof(struct inode *)) ||

		    copy_from_kernel_nofault(&a_ops, &mapping->a_ops,

				sizeof(struct address_space_operations *))) {

			pr_warn("failed to read mapping->host or a_ops, mapping not a valid kernel address?\n");

		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("mapping->a_ops:%ps\n", a_ops);

			pr_warn("aops:%ps\n", a_ops);

			goto out_mapping;

		}



		if (copy_from_kernel_nofault(&dentry_first,

			&host->i_dentry.first, sizeof(struct hlist_node *))) {

			pr_warn("mapping->a_ops:%ps with invalid mapping->host inode address %px\n",

		if (get_kernel_nofault(dentry_first, &host->i_dentry.first)) {

			pr_warn("aops:%ps with invalid host inode %px\n",

					a_ops, host);

			goto out_mapping;

		}



		if (!dentry_first) {

			pr_warn("mapping->a_ops:%ps\n", a_ops);

			pr_warn("aops:%ps\n", a_ops);

			goto out_mapping;

		}



		dentry_ptr = container_of(dentry_first, struct dentry, d_u.d_alias);

		if (copy_from_kernel_nofault(&dentry, dentry_ptr,

							sizeof(struct dentry))) {

			pr_warn("mapping->aops:%ps with invalid mapping->host->i_dentry.first %px\n",

				a_ops, dentry_ptr);

		if (get_kernel_nofault(dentry, dentry_ptr)) {

			pr_warn("aops:%ps with invalid dentry %px\n", a_ops,

					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("mapping->aops:%ps dentry name:\"%pd\"\n",

								a_ops, &dentry);

			pr_warn("aops:%ps dentry name:\"%pd\"\n", a_ops,

					&dentry);

		}

	}

out_mapping: