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[PATCH RESEND v3 0/2] Adjust lockdep static allocations for sparc

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  [PATCH RESEND v3 0/2] Adjust lockdep static allocations for sparc Babu Moger <babu.moger@oracle.com> - 2016-11-02 17:40 +0100
    [PATCH RESEND v3 1/2] config: Adding the new config parameter CONFIG_PROVE_LOCKING_SMALL for sparc Babu Moger <babu.moger@oracle.com> - 2016-11-02 17:40 +0100

#1513960 — [PATCH RESEND v3 0/2] Adjust lockdep static allocations for sparc

Looks like these patches are lost in the mix. Resending with following note.

Dave, This requires your Ack as it touches sparc. Peter is waiting
for your Ack to queue it. Here is our previous discussion.
http://marc.info/?t=147500486300001&r=1&w=2

These patches limit the static allocations for lockdep data structures
used for debugging locking correctness. For sparc, all the kernel's code,
data, and bss, must have locked translations in the TLB so that we don't
get TLB misses on kernel code and data. Current sparc chips have 8 TLB
entries available that may be locked down, and with a 4mb page size,
this gives a maximum of 32MB. With PROVE_LOCKING we could go over this
limit and cause system boot-up problems. These patches limit the static
allocations so that everything fits in current required size limit.

patch 1 : Adds new config parameter CONFIG_PROVE_LOCKING_SMALL
Patch 2 : Adjusts the sizes based on the new config parameter

v2-> v3:
   Some more comments from Sam Ravnborg and Peter Zijlstra.
   Defined PROVE_LOCKING_SMALL as invisible and moved the selection to
   arch/sparc/Kconfig. 

v1-> v2:
   As suggested by Peter Zijlstra, keeping the default as is.
   Introduced new config variable CONFIG_PROVE_LOCKING_SMALL
   to handle sparc specific case.

v0:
   Initial revision.

Babu Moger (2):
  config: Adding the new config parameter CONFIG_PROVE_LOCKING_SMALL
    for sparc
  lockdep: Limit static allocations if PROVE_LOCKING_SMALL is defined

 arch/sparc/Kconfig                 |    1 +
 kernel/locking/lockdep_internals.h |   20 +++++++++++++++++---
 lib/Kconfig.debug                  |    3 +++
 3 files changed, 21 insertions(+), 3 deletions(-)

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#1513961 — [PATCH RESEND v3 1/2] config: Adding the new config parameter CONFIG_PROVE_LOCKING_SMALL for sparc

This new config parameter limits the space used for "Lock debugging:
prove locking correctness" by about 4MB. The current sparc systems have
the limitation of 32MB size for kernel size including .text, .data and
.bss sections. With PROVE_LOCKING feature, the kernel size could grow
beyond this limit and causing system boot-up issues. With this option,
kernel limits the size of the entries of lock_chains, stack_trace etc.,
so that kernel fits in required size limit. This is not visible to user
and only used for sparc.

Signed-off-by: Babu Moger <babu.moger@oracle.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
 arch/sparc/Kconfig |    1 +
 lib/Kconfig.debug  |    3 +++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index b23c76b..a85e51d 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -43,6 +43,7 @@ config SPARC
 	select ARCH_HAS_SG_CHAIN
 	select CPU_NO_EFFICIENT_FFS
 	select HAVE_ARCH_HARDENED_USERCOPY
+	select PROVE_LOCKING_SMALL if PROVE_LOCKING
 
 config SPARC32
 	def_bool !64BIT
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index b01e547..a6c8db1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1085,6 +1085,9 @@ config PROVE_LOCKING
 
 	 For more details, see Documentation/locking/lockdep-design.txt.
 
+config PROVE_LOCKING_SMALL
+	bool
+
 config LOCKDEP
 	bool
 	depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
-- 
1.7.1

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