mm: kmemleak: use the memory pool for early allocations

Currently kmemleak uses a static early_log buffer to trace all memory
allocation/freeing before the slab allocator is initialised.  Such early
log is replayed during kmemleak_init() to properly initialise the kmemleak
metadata for objects allocated up that point.  With a memory pool that
does not rely on the slab allocator, it is possible to skip this early log
entirely.

In order to remove the early logging, consider kmemleak_enabled == 1 by
default while the kmem_cache availability is checked directly on the
object_cache and scan_area_cache variables.  The RCU callback is only
invoked after object_cache has been initialised as we wouldn't have any
concurrent list traversal before this.

In order to reduce the number of callbacks before kmemleak is fully
initialised, move the kmemleak_init() call to mm_init().

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: remove WARN_ON(), per Catalin]
Link: http://lkml.kernel.org/r/20190812160642.52134-4-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/init/main.c b/init/main.c
index 653693da8da6..3ca67e8b92fd 100644
--- a/init/main.c
+++ b/init/main.c
@@ -556,6 +556,7 @@ static void __init mm_init(void)
 	report_meminit();
 	mem_init();
 	kmem_cache_init();
+	kmemleak_init();
 	pgtable_init();
 	debug_objects_mem_init();
 	vmalloc_init();
@@ -740,7 +741,6 @@ asmlinkage __visible void __init start_kernel(void)
 		initrd_start = 0;
 	}
 #endif
-	kmemleak_init();
 	setup_per_cpu_pageset();
 	numa_policy_init();
 	acpi_early_init();