Re: [PATCH v3 2/2] lockdep: Limit static allocations if PROVE_LOCKING_SMALL is defined

From: Babu Moger
Date: Thu Sep 29 2016 - 09:56:33 EST


CCing Dave.

Dave, Please ack it if it looks good. Thanks.


On 9/27/2016 2:33 PM, Babu Moger wrote:
Reduce the size of data structure for lockdep entries by half if
PROVE_LOCKING_SMALL if defined. This is used only for sparc.

Signed-off-by: Babu Moger <babu.moger@xxxxxxxxxx>
---
kernel/locking/lockdep_internals.h | 20 +++++++++++++++++---
1 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index 51c4b24..c2b8849 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -46,6 +46,14 @@ enum {
(LOCKF_USED_IN_HARDIRQ_READ | LOCKF_USED_IN_SOFTIRQ_READ)
/*
+ * CONFIG_PROVE_LOCKING_SMALL is defined for sparc. Sparc requires .text,
+ * .data and .bss to fit in required 32MB limit for the kernel. With
+ * PROVE_LOCKING we could go over this limit and cause system boot-up problems.
+ * So, reduce the static allocations for lockdeps related structures so that
+ * everything fits in current required size limit.
+ */
+#ifdef CONFIG_PROVE_LOCKING_SMALL
+/*
* MAX_LOCKDEP_ENTRIES is the maximum number of lock dependencies
* we track.
*
@@ -54,18 +62,24 @@ enum {
* table (if it's not there yet), and we check it for lock order
* conflicts and deadlocks.
*/
+#define MAX_LOCKDEP_ENTRIES 16384UL
+#define MAX_LOCKDEP_CHAINS_BITS 15
+#define MAX_STACK_TRACE_ENTRIES 262144UL
+#else
#define MAX_LOCKDEP_ENTRIES 32768UL
#define MAX_LOCKDEP_CHAINS_BITS 16
-#define MAX_LOCKDEP_CHAINS (1UL << MAX_LOCKDEP_CHAINS_BITS)
-
-#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
/*
* Stack-trace: tightly packed array of stack backtrace
* addresses. Protected by the hash_lock.
*/
#define MAX_STACK_TRACE_ENTRIES 524288UL
+#endif
+
+#define MAX_LOCKDEP_CHAINS (1UL << MAX_LOCKDEP_CHAINS_BITS)
+
+#define MAX_LOCKDEP_CHAIN_HLOCKS (MAX_LOCKDEP_CHAINS*5)
extern struct list_head all_lock_classes;
extern struct lock_chain lock_chains[];