mm/vmalloc: query dynamic DEBUG_PAGEALLOC setting (f48d97f3) · Commits · 戴 / test

As CONFIG_DEBUG_PAGEALLOC can be enabled/disabled via kernel parameters we can optimize some cases by checking the enablement state. This is follow-up work for Christian's Optimize CONFIG_DEBUG_PAGEALLOC: https://lkml.org/lkml/2016/1/27/194 Remaining work is to make sparc to be aware of this but it looks not easy for me so I skip that in this series. This patch (of 5): We can disable debug_pagealloc processing even if the code is complied with CONFIG_DEBUG_PAGEALLOC. This patch changes the code to query whether it is enabled or not in runtime. [akpm@linux-foundation.org: update comment, per David. Adjust comment to use 80 cols] Signed-off-by:

Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by:

Christian Borntraeger <borntraeger@de.ibm.com> Acked-by:

David Rientjes <rientjes@google.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Takashi Iwai <tiwai@suse.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/vmalloc.c

+12 −13

Original line number	Original line	Diff line number	Diff line
	@@ -531,22 +531,21 @@ static void unmap_vmap_area(struct vmap_area *va)
	static void vmap_debug_free_range(unsigned long start, unsigned long end)		static void vmap_debug_free_range(unsigned long start, unsigned long end)
	{		{
	/*		/*
	* Unmap page tables and force a TLB flush immediately if		* Unmap page tables and force a TLB flush immediately if pagealloc
	* CONFIG_DEBUG_PAGEALLOC is set. This catches use after free		* debugging is enabled. This catches use after free bugs similarly to
	* bugs similarly to those in linear kernel virtual address		* those in linear kernel virtual address space after a page has been
	* space after a page has been freed.		* freed.
	*		*
	* All the lazy freeing logic is still retained, in order to		* All the lazy freeing logic is still retained, in order to minimise
	* minimise intrusiveness of this debugging feature.		* intrusiveness of this debugging feature.
	*		*
	* This is going to be slow (linear kernel virtual address		* This is going to be slow (linear kernel virtual address debugging
	* debugging doesn't do a broadcast TLB flush so it is a lot		* doesn't do a broadcast TLB flush so it is a lot faster).
	* faster).
	*/		*/
	#ifdef CONFIG_DEBUG_PAGEALLOC		if (debug_pagealloc_enabled()) {
	vunmap_page_range(start, end);		vunmap_page_range(start, end);
	flush_tlb_kernel_range(start, end);		flush_tlb_kernel_range(start, end);
	#endif		}
	}		}

	/*		/*

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