The linux-next commit "mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options" [1] introduced a false positive when init_on_free=1 and page_poison=on, due to the page_poison expects the pattern 0xaa when allocating pages which were overwritten by init_on_free=1 with 0.
Fix it by switching the order between kernel_init_free_pages() and kernel_poison_pages() in free_pages_prepare(). [1] https://patchwork.kernel.org/patch/10999465/ Signed-off-by: Qian Cai <c...@lca.pw> --- v2: After further debugging, the issue after switching order is likely a separate issue as clear_page() should not cause issues with future accesses. mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 54dacf35d200..32bbd30c5f85 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1172,9 +1172,10 @@ static __always_inline bool free_pages_prepare(struct page *page, PAGE_SIZE << order); } arch_free_page(page, order); - kernel_poison_pages(page, 1 << order, 0); if (want_init_on_free()) kernel_init_free_pages(page, 1 << order); + + kernel_poison_pages(page, 1 << order, 0); if (debug_pagealloc_enabled()) kernel_map_pages(page, 1 << order, 0); -- 1.8.3.1
