Commit 9ea9a680 authored Aug 17, 2018 by Michal Hocko Committed by Linus Torvalds Aug 17, 2018

mm: drop VM_BUG_ON from __get_free_pages

There is no real reason to blow up just because the caller doesn't know
that __get_free_pages cannot return highmem pages.  Simply fix that up
silently.  Even if we have some confused users such a fixup will not be
harmful.

[akpm@linux-foundation.org: mask off __GFP_HIGHMEM]
Link: http://lkml.kernel.org/r/20180622162841.25114-1-mhocko@kernel.org


Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiankang Chen <chenjiankang1@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 974e6d66

mm/page_alloc.c

+4 −8

Original line number	Diff line number	Diff line
		@@ -4404,19 +4404,15 @@ out:
		EXPORT_SYMBOL(__alloc_pages_nodemask);

		/*
		* Common helper functions.
		* Common helper functions. Never use with __GFP_HIGHMEM because the returned
		* address cannot represent highmem pages. Use alloc_pages and then kmap if
		* you need to access high mem.
		*/
		unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order)
		{
		struct page *page;

		/*
		* __get_free_pages() returns a virtual address, which cannot represent
		* a highmem page
		*/
		VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);

		page = alloc_pages(gfp_mask, order);
		page = alloc_pages(gfp_mask & ~__GFP_HIGHMEM, order);
		if (!page)
		return 0;
		return (unsigned long) page_address(page);

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