On Sat, 6 Mar 2021 00:36:33 +0100 Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote: > Currently, kasan_free_nondeferred_pages()->kasan_free_pages() is called > after debug_pagealloc_unmap_pages(). This causes a crash when > debug_pagealloc is enabled, as HW_TAGS KASAN can't set tags on an > unmapped page. > > This patch puts kasan_free_nondeferred_pages() before > debug_pagealloc_unmap_pages() and arch_free_page(), which can also make > the page unavailable. > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1304,6 +1304,12 @@ static __always_inline bool free_pages_prepare(struct page *page, > > kernel_poison_pages(page, 1 << order); > > + /* > + * With hardware tag-based KASAN, memory tags must be set before the > + * page becomes unavailable via debug_pagealloc or arch_free_page. > + */ > + kasan_free_nondeferred_pages(page, order, fpi_flags); > + > /* > * arch_free_page() can make the page's contents inaccessible. s390 > * does this. So nothing which can access the page's contents should > @@ -1313,8 +1319,6 @@ static __always_inline bool free_pages_prepare(struct page *page, > > debug_pagealloc_unmap_pages(page, 1 << order); > > - kasan_free_nondeferred_pages(page, order, fpi_flags); > - > return true; > } kasan_free_nondeferred_pages() has only two args in current mainline. I fixed that in the obvious manner...
