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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-04-01 21:05:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-02 09:35:27 -0700
commit6197ab984b4190d79cf5ccf39b25868730e83e2b (patch)
treeb8bf002f719420247dc04487d89e18494be2712e /mm/debug.c
parentbe87141108f0f5ecbd094d921981dbc52f646c33 (diff)
downloadlinux-6197ab984b4190d79cf5ccf39b25868730e83e2b.tar.bz2
mm: improve dump_page() for compound pages
There was no protection against a corrupted struct page having an implausible compound_head(). Sanity check that a compound page has a head within reach of the maximum allocatable page (this will need to be adjusted if one of the plans to allocate 1GB pages comes to fruition). In addition, - Print the mapping pointer using %p insted of %px. The actual value of the pointer can be read out of the raw page dump and using %p gives a chance to correlate it with an earlier printk of the mapping pointer - Print the mapping pointer from the head page, not the tail page (the tail ->mapping pointer may be in use for other purposes, eg part of a list_head) - Print the order of the page for compound pages - Dump the raw head page as well as the raw page - Print the refcount from the head page, not the tail page Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Co-developed-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Link: http://lkml.kernel.org/r/20200211001536.1027652-12-jhubbard@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/debug.c')
-rw-r--r--mm/debug.c33
1 files changed, 23 insertions, 10 deletions
diff --git a/mm/debug.c b/mm/debug.c
index ecccd9f17801..f5ffb0784559 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -44,8 +44,10 @@ const struct trace_print_flags vmaflag_names[] = {
void __dump_page(struct page *page, const char *reason)
{
+ struct page *head = compound_head(page);
struct address_space *mapping;
bool page_poisoned = PagePoisoned(page);
+ bool compound = PageCompound(page);
/*
* Accessing the pageblock without the zone lock. It could change to
* "isolate" again in the meantime, but since we are just dumping the
@@ -66,25 +68,32 @@ void __dump_page(struct page *page, const char *reason)
goto hex_only;
}
- mapping = page_mapping(page);
+ if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
+ /* Corrupt page, cannot call page_mapping */
+ mapping = page->mapping;
+ head = page;
+ compound = false;
+ } else {
+ mapping = page_mapping(page);
+ }
/*
* Avoid VM_BUG_ON() in page_mapcount().
* page->_mapcount space in struct page is used by sl[aou]b pages to
* encode own info.
*/
- mapcount = PageSlab(page) ? 0 : page_mapcount(page);
+ mapcount = PageSlab(head) ? 0 : page_mapcount(page);
- if (PageCompound(page))
- pr_warn("page:%px refcount:%d mapcount:%d mapping:%px "
- "index:%#lx compound_mapcount: %d\n",
- page, page_ref_count(page), mapcount,
- page->mapping, page_to_pgoff(page),
- compound_mapcount(page));
+ if (compound)
+ pr_warn("page:%px refcount:%d mapcount:%d mapping:%p "
+ "index:%#lx head:%px order:%u compound_mapcount:%d\n",
+ page, page_ref_count(head), mapcount,
+ mapping, page_to_pgoff(page), head,
+ compound_order(head), compound_mapcount(page));
else
- pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n",
+ pr_warn("page:%px refcount:%d mapcount:%d mapping:%p index:%#lx\n",
page, page_ref_count(page), mapcount,
- page->mapping, page_to_pgoff(page));
+ mapping, page_to_pgoff(page));
if (PageKsm(page))
type = "ksm ";
else if (PageAnon(page))
@@ -106,6 +115,10 @@ hex_only:
print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32,
sizeof(unsigned long), page,
sizeof(struct page), false);
+ if (head != page)
+ print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32,
+ sizeof(unsigned long), head,
+ sizeof(struct page), false);
if (reason)
pr_warn("page dumped because: %s\n", reason);