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author | Pavel Tatashin <pasha.tatashin@oracle.com> | 2018-07-04 02:02:53 +0200 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-07-04 02:32:19 +0200 |
commit | fc36def997cfd6cbff3eda4f82853a5c311c5466 (patch) | |
tree | 30bcbc53d846d0af57df66256968458590cb7cd7 /mm | |
parent | ARM: disable KCOV for trusted foundations code (diff) | |
download | linux-fc36def997cfd6cbff3eda4f82853a5c311c5466.tar.xz linux-fc36def997cfd6cbff3eda4f82853a5c311c5466.zip |
mm: teach dump_page() to correctly output poisoned struct pages
If struct page is poisoned, and uninitialized access is detected via
PF_POISONED_CHECK(page) dump_page() is called to output the page. But,
the dump_page() itself accesses struct page to determine how to print
it, and therefore gets into a recursive loop.
For example:
dump_page()
__dump_page()
PageSlab(page)
PF_POISONED_CHECK(page)
VM_BUG_ON_PGFLAGS(PagePoisoned(page), page)
dump_page() recursion loop.
Link: http://lkml.kernel.org/r/20180702180536.2552-1-pasha.tatashin@oracle.com
Fixes: f165b378bbdf ("mm: uninitialized struct page poisoning sanity checking")
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/debug.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/mm/debug.c b/mm/debug.c index 56e2d9125ea5..38c926520c97 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -43,12 +43,25 @@ const struct trace_print_flags vmaflag_names[] = { void __dump_page(struct page *page, const char *reason) { + bool page_poisoned = PagePoisoned(page); + int mapcount; + + /* + * If struct page is poisoned don't access Page*() functions as that + * leads to recursive loop. Page*() check for poisoned pages, and calls + * dump_page() when detected. + */ + if (page_poisoned) { + pr_emerg("page:%px is uninitialized and poisoned", page); + goto hex_only; + } + /* * Avoid VM_BUG_ON() in page_mapcount(). * page->_mapcount space in struct page is used by sl[aou]b pages to * encode own info. */ - int mapcount = PageSlab(page) ? 0 : page_mapcount(page); + mapcount = PageSlab(page) ? 0 : page_mapcount(page); pr_emerg("page:%px count:%d mapcount:%d mapping:%px index:%#lx", page, page_ref_count(page), mapcount, @@ -60,6 +73,7 @@ void __dump_page(struct page *page, const char *reason) pr_emerg("flags: %#lx(%pGp)\n", page->flags, &page->flags); +hex_only: print_hex_dump(KERN_ALERT, "raw: ", DUMP_PREFIX_NONE, 32, sizeof(unsigned long), page, sizeof(struct page), false); @@ -68,7 +82,7 @@ void __dump_page(struct page *page, const char *reason) pr_alert("page dumped because: %s\n", reason); #ifdef CONFIG_MEMCG - if (page->mem_cgroup) + if (!page_poisoned && page->mem_cgroup) pr_alert("page->mem_cgroup:%px\n", page->mem_cgroup); #endif } |