linux-kernel - [2.6.35-rc6 patch] increase kmemleak robustness at boot

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Date:	Wed, 28 Jul 2010 17:40:52 +0100
From:	Daniel J Blueman <daniel.blueman@...il.com>
To:	Catalin Marinas <catalin.marinas@...il.com>
Cc:	Pekka Enberg <penberg@...helsinki.fi>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: [2.6.35-rc6 patch] increase kmemleak robustness at boot

Hi Catalin,

I've consistently been experiencing kmemleak exhaust it's 400-entry
early-boot buffer and disabling itself; there have been reports of
this also, and I'm finding this on x86-64 with various debug options
enabled.

If we issue a warning and allow the buffer to wrap, we don't need to
hit the kill-switch. While we lose track of some early potential
leaks, it's better than no functionality.

Let me know if it's acceptable, and many thanks for such an excellent tool,
  Daniel

---

Allow the early-boot buffer to wrap, rather than disabling kmemleak
and losing the functionality.

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 2c0d032..93bf8a3 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -786,13 +786,6 @@ static void __init log_early(int op_type, const
void *ptr, size_t size,
 	unsigned long flags;
 	struct early_log *log;

-	if (crt_early_log >= ARRAY_SIZE(early_log)) {
-		pr_warning("Early log buffer exceeded, "
-			   "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
-		kmemleak_disable();
-		return;
-	}
-
 	/*
 	 * There is no need for locking since the kernel is still in UP mode
 	 * at this stage. Disabling the IRQs is enough.
@@ -805,7 +798,13 @@ static void __init log_early(int op_type, const
void *ptr, size_t size,
 	log->min_count = min_count;
 	if (op_type == KMEMLEAK_ALLOC)
 		log->trace_len = __save_stack_trace(log->trace);
+
 	crt_early_log++;
+	if (crt_early_log >= ARRAY_SIZE(early_log)) {
+		pr_warning("Early log buffer exhausted - wrapping\n");
+		crt_early_log = 0;
+	}
+	
 	local_irq_restore(flags);
 }

-- 
Daniel J Blueman
--
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