On Wed, May 12, 2021 at 11:10:57AM +0800, Kefeng Wang wrote: > If page is poisoned, it will crash when we call some page related > functions, so must check whether the page is poisoned or not firstly. https://lore.kernel.org/linux-mm/20210430145549.2662354-4-willy@xxxxxxxxxxxxx/ > Fixes: 6197ab984b41 ("mm: improve dump_page() for compound pages") > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> > --- > mm/debug.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/mm/debug.c b/mm/debug.c > index 84cdcd0f7bd3..cf84cd9df527 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -44,20 +44,19 @@ const struct trace_print_flags vmaflag_names[] = { > > static void __dump_page(struct page *page, const char *reason) > { > - struct page *head = compound_head(page); > + struct page *head = NULL; > struct address_space *mapping; > - bool page_poisoned = PagePoisoned(page); > - bool compound = PageCompound(page); > + bool compound; > /* > * Accessing the pageblock without the zone lock. It could change to > * "isolate" again in the meantime, but since we are just dumping the > * state for debugging, it should be fine to accept a bit of > * inaccuracy here due to racing. > */ > - bool page_cma = is_migrate_cma_page(page); > + bool page_cma; > int mapcount; > char *type = ""; > - > + bool page_poisoned = PagePoisoned(page); > /* > * If struct page is poisoned don't access Page*() functions as that > * leads to recursive loop. Page*() check for poisoned pages, and calls > @@ -68,6 +67,10 @@ static void __dump_page(struct page *page, const char *reason) > goto hex_only; > } > > + head = compound_head(page); > + page_poisoned = PagePoisoned(page); > + page_cma = is_migrate_cma_page(page); > + > if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) { > /* > * Corrupt page, so we cannot call page_mapping. Instead, do a > @@ -178,7 +181,7 @@ static void __dump_page(struct page *page, const char *reason) > print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, > sizeof(unsigned long), page, > sizeof(struct page), false); > - if (head != page) > + if (head && head != page) > print_hex_dump(KERN_WARNING, "head: ", DUMP_PREFIX_NONE, 32, > sizeof(unsigned long), head, > sizeof(struct page), false); > -- > 2.26.2 > >
