From f48d97f340cbb0c323fa7a7b36bd76a108a9f49f Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Thu, 17 Mar 2016 14:17:49 -0700 Subject: [PATCH] mm/vmalloc: query dynamic DEBUG_PAGEALLOC setting 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 Reviewed-by: Christian Borntraeger Acked-by: David Rientjes Cc: Benjamin Herrenschmidt Cc: Takashi Iwai Cc: Chris Metcalf Cc: Christoph Lameter Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index fb42a5bffe47..d4b2e34adae0 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -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) { /* - * Unmap page tables and force a TLB flush immediately if - * CONFIG_DEBUG_PAGEALLOC is set. This catches use after free - * bugs similarly to those in linear kernel virtual address - * space after a page has been freed. + * Unmap page tables and force a TLB flush immediately if pagealloc + * debugging is enabled. This catches use after free bugs similarly to + * those in linear kernel virtual address space after a page has been + * freed. * - * All the lazy freeing logic is still retained, in order to - * minimise intrusiveness of this debugging feature. + * All the lazy freeing logic is still retained, in order to minimise + * intrusiveness of this debugging feature. * - * This is going to be *slow* (linear kernel virtual address - * debugging doesn't do a broadcast TLB flush so it is a lot - * faster). + * This is going to be *slow* (linear kernel virtual address debugging + * doesn't do a broadcast TLB flush so it is a lot faster). */ -#ifdef CONFIG_DEBUG_PAGEALLOC - vunmap_page_range(start, end); - flush_tlb_kernel_range(start, end); -#endif + if (debug_pagealloc_enabled()) { + vunmap_page_range(start, end); + flush_tlb_kernel_range(start, end); + } } /* -- 2.20.1