From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: 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. Link: http://lkml.kernel.org/r/20200709202117.7216-5-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: John Hubbard <jhubbard@xxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> Cc: William Kucharski <william.kucharski@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/debug.c | 36 ++++++++++++++++-------------------- 1 file changed, 16 insertions(+), 20 deletions(-) --- a/mm/debug.c~mm-switch-dump_page-to-get_kernel_nofault +++ a/mm/debug.c @@ -115,54 +115,50 @@ void __dump_page(struct page *page, cons 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", - a_ops, host); + 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: _
