From 6626c5d53bc45c59798628677ba5606f02e371f3 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 22 Mar 2006 00:08:42 -0800 Subject: [PATCH] [PATCH] mm: prep_zero_page() in irq is a bug prep_zero_page() uses KM_USER0 and hence may not be used from IRQ context, at least for highmem pages. Cc: Nick Piggin Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index bdff858996..ed91684cb1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -217,6 +217,11 @@ static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags) int i; BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM); + /* + * clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO + * and __GFP_HIGHMEM from hard or soft interrupt context. + */ + BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt()); for (i = 0; i < (1 << order); i++) clear_highpage(page + i); } -- 2.39.5