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Subject[PATCH v4 3/3] mm/vmap: add DEBUG_AUGMENT_LOWEST_MATCH_CHECK macro
Date
This macro adds some debug code to check that vmap allocations
are happened in ascending order.

By default this option is set to 0 and not active. It requires
recompilation of the kernel to activate it. Set to 1, compile
the kernel.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
---
mm/vmalloc.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a74e605e042f..92b784d8088c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -325,6 +325,7 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
/*** Global kva allocator ***/

#define DEBUG_AUGMENT_PROPAGATE_CHECK 0
+#define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0

#define VM_LAZY_FREE 0x02
#define VM_VM_AREA 0x04
@@ -833,6 +834,44 @@ find_vmap_lowest_match(unsigned long size,
return NULL;
}

+#if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
+#include <linux/random.h>
+
+static struct vmap_area *
+find_vmap_lowest_linear_match(unsigned long size,
+ unsigned long align, unsigned long vstart)
+{
+ struct vmap_area *va;
+
+ list_for_each_entry(va, &free_vmap_area_list, list) {
+ if (!is_within_this_va(va, size, align, vstart))
+ continue;
+
+ return va;
+ }
+
+ return NULL;
+}
+
+static void
+find_vmap_lowest_match_check(unsigned long size)
+{
+ struct vmap_area *va_1, *va_2;
+ unsigned long vstart;
+ unsigned int rnd;
+
+ get_random_bytes(&rnd, sizeof(rnd));
+ vstart = VMALLOC_START + rnd;
+
+ va_1 = find_vmap_lowest_match(size, 1, vstart);
+ va_2 = find_vmap_lowest_linear_match(size, 1, vstart);
+
+ if (va_1 != va_2)
+ pr_emerg("not lowest: t: 0x%p, l: 0x%p, v: 0x%lx\n",
+ va_1, va_2, vstart);
+}
+#endif
+
enum fit_type {
NOTHING_FIT = 0,
FL_FIT_TYPE = 1, /* full fit */
@@ -975,6 +1014,10 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
if (ret)
return vend;

+#if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
+ find_vmap_lowest_match_check(size);
+#endif
+
return nva_start_addr;
}

--
2.11.0
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