kmemleak: Handle percpu memory allocation

This patch adds kmemleak callbacks from the percpu allocator, reducing a
number of false positives caused by kmemleak not scanning such memory
blocks. The percpu chunks are never reported as leaks because of current
kmemleak limitations with the __percpu pointer not pointing directly to
the actual chunks.

Reported-by: Huajun Li <huajun.li.lee@gmail.com>
Acked-by: Christoph Lameter <cl@gentwo.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/mm/percpu.c b/mm/percpu.c
index 3bb810a72006..86c5bdbdc370 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -67,6 +67,7 @@
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
 #include <linux/workqueue.h>
+#include <linux/kmemleak.h>
 
 #include <asm/cacheflush.h>
 #include <asm/sections.h>
@@ -710,6 +711,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
         const char *err;
         int slot, off, new_alloc;
         unsigned long flags;
+        void __percpu *ptr;
 
         if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
                 WARN(true, "illegal size (%zu) or align (%zu) for "
@@ -802,7 +804,9 @@ area_found:
         mutex_unlock(&pcpu_alloc_mutex);
 
         /* return address relative to base address */
-        return __addr_to_pcpu_ptr(chunk->base_addr + off);
+        ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
+        kmemleak_alloc_percpu(ptr, size);
+        return ptr;
 
 fail_unlock:
         spin_unlock_irqrestore(&pcpu_lock, flags);
@@ -916,6 +920,8 @@ void free_percpu(void __percpu *ptr)
         if (!ptr)
                 return;
 
+        kmemleak_free_percpu(ptr);
+
         addr = __pcpu_ptr_to_addr(ptr);
 
         spin_lock_irqsave(&pcpu_lock, flags);
@@ -1637,6 +1643,8 @@ int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
                         rc = -ENOMEM;
                         goto out_free_areas;
                 }
+                /* kmemleak tracks the percpu allocations separately */
+                kmemleak_free(ptr);
                 areas[group] = ptr;
 
                 base = min(ptr, base);
@@ -1751,6 +1759,8 @@ int __init pcpu_page_first_chunk(size_t reserved_size,
                                            "for cpu%u\n", psize_str, cpu);
                                 goto enomem;
                         }
+                        /* kmemleak tracks the percpu allocations separately */
+                        kmemleak_free(ptr);
                         pages[j++] = virt_to_page(ptr);
                 }