Messages in this thread | | | Date | Wed, 1 Dec 2021 15:09:56 +0100 | From | Marco Elver <> | Subject | Re: [PATCH 04/31] kasan, page_alloc: simplify kasan_poison_pages call site |
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On Tue, Nov 30, 2021 at 10:39PM +0100, andrey.konovalov@linux.dev wrote: > From: Andrey Konovalov <andreyknvl@google.com> > > Simplify the code around calling kasan_poison_pages() in > free_pages_prepare(). > > Reording kasan_poison_pages() and kernel_init_free_pages() is OK, > since kernel_init_free_pages() can handle poisoned memory.
Why did they have to be reordered?
> This patch does no functional changes besides reordering the calls. > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > --- > mm/page_alloc.c | 18 +++++------------- > 1 file changed, 5 insertions(+), 13 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 3f3ea41f8c64..0673db27dd12 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1289,6 +1289,7 @@ static __always_inline bool free_pages_prepare(struct page *page, > { > int bad = 0; > bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
skip_kasan_poison is only used once now, so you could remove the variable -- unless later code will use it in more than once place again.
> + bool init = want_init_on_free(); > > VM_BUG_ON_PAGE(PageTail(page), page); > > @@ -1359,19 +1360,10 @@ static __always_inline bool free_pages_prepare(struct page *page, > * With hardware tag-based KASAN, memory tags must be set before the > * page becomes unavailable via debug_pagealloc or arch_free_page. > */ > - if (kasan_has_integrated_init()) { > - bool init = want_init_on_free(); > - > - if (!skip_kasan_poison) > - kasan_poison_pages(page, order, init); > - } else { > - bool init = want_init_on_free(); > - > - if (init) > - kernel_init_free_pages(page, 1 << order); > - if (!skip_kasan_poison) > - kasan_poison_pages(page, order, init); > - } > + if (!skip_kasan_poison) > + kasan_poison_pages(page, order, init); > + if (init && !kasan_has_integrated_init()) > + kernel_init_free_pages(page, 1 << order); > > /* > * arch_free_page() can make the page's contents inaccessible. s390 > -- > 2.25.1
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