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Commit 6626c5d5 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
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[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 <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 17cf4406

mm/page_alloc.c

+5 −0
Original line number Diff line number Diff line
@@ -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);

}