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 <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>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index fb42a5b..d4b2e34 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -531,22 +531,21 @@
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);
+ }
}
/*