linux-kernel - [PATCH RESEND v3 2/2] lockdep: Limit static allocations if PROVE_LOCKING

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Date:   Wed,  2 Nov 2016 09:36:33 -0700
From:   Babu Moger <babu.moger@...cle.com>
To:     davem@...emloft.net, peterz@...radead.org,
        akpm@...ux-foundation.org
Cc:     keescook@...omium.org, mingo@...nel.org,
        paulmck@...ux.vnet.ibm.com, dan.j.williams@...el.com,
        tj@...nel.org, jpoimboe@...hat.com, nikolay@...ulusnetworks.com,
        dvyukov@...gle.com, sam@...nborg.org, shuah@...nel.org,
        sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org,
        rob.gardner@...cle.com, babu.moger@...cle.com
Subject: [PATCH RESEND v3 2/2] lockdep: Limit static allocations if PROVE_LOCKING_SMALL is defined

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@...cle.com>
Acked-by: Sam Ravnborg <sam@...nborg.org>
---
 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[];
-- 
1.7.1