diff options
| author | Oscar Salvador | 2019-03-28 20:44:01 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2019-03-29 10:01:37 -0700 |
| commit | 5ae2efb1dea9f537453e841714e3ee2757595aec (patch) | |
| tree | ec6d21ee6dcb327485349c6605b57992caffd00e | |
| parent | a7f40cfe3b7ada57af9b62fd28430eeb4a7cfcb7 (diff) | |
mm/debug.c: fix __dump_page when mapping->host is not set
While debugging something, I added a dump_page() into do_swap_page(),
and I got the splat from below. The issue happens when dereferencing
mapping->host in __dump_page():
...
else if (mapping) {
pr_warn("%ps ", mapping->a_ops);
if (mapping->host->i_dentry.first) {
struct dentry *dentry;
dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias);
pr_warn("name:\"%pd\" ", dentry);
}
}
...
Swap address space does not contain an inode information, and so
mapping->host equals NULL.
Although the dump_page() call was added artificially into
do_swap_page(), I am not sure if we can hit this from any other path, so
it looks worth fixing it. We can easily do that by checking
mapping->host first.
Link: http://lkml.kernel.org/r/20190318072931.29094-1-osalvador@suse.de
Fixes: 1c6fb1d89e73c ("mm: print more information about mapping in __dump_page")
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/debug.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/debug.c b/mm/debug.c index 45d9eb77b84e..eee9c221280c 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -79,7 +79,7 @@ void __dump_page(struct page *page, const char *reason) pr_warn("ksm "); else if (mapping) { pr_warn("%ps ", mapping->a_ops); - if (mapping->host->i_dentry.first) { + if (mapping->host && mapping->host->i_dentry.first) { struct dentry *dentry; dentry = container_of(mapping->host->i_dentry.first, struct dentry, d_u.d_alias); pr_warn("name:\"%pd\" ", dentry); |