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Commit 63b1a816 authored by Heiko Carstens's avatar Heiko Carstens Committed by Ingo Molnar
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futexes: Fix futex_hashsize initialization 



"futexes: Increase hash table size for better performance"
introduces a new alloc_large_system_hash() call.

alloc_large_system_hash() however may allocate less memory than
requested, e.g. limited by MAX_ORDER.

Hence pass a pointer to alloc_large_system_hash() which will
contain the hash shift when the function returns. Afterwards
correctly set futex_hashsize.

Fixes a crash on s390 where the requested allocation size was
4MB but only 1MB was allocated.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Link: http://lkml.kernel.org/r/20140116135450.GA4345@osiris


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f549ed1a

kernel/futex.c

+4 −2
Original line number Diff line number Diff line
@@ -2844,6 +2844,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, 
static int __init futex_init(void)

{

	u32 curval;

	unsigned int futex_shift;

	unsigned long i;



#if CONFIG_BASE_SMALL
@@ -2855,8 +2856,9 @@ static int __init futex_init(void) 
	futex_queues = alloc_large_system_hash("futex", sizeof(*futex_queues),

					       futex_hashsize, 0,

					       futex_hashsize < 256 ? HASH_SMALL : 0,

					       NULL, NULL, futex_hashsize, futex_hashsize);



					       &futex_shift, NULL,

					       futex_hashsize, futex_hashsize);

	futex_hashsize = 1UL << futex_shift;

	/*

	 * This will fail and we want it. Some arch implementations do

	 * runtime detection of the futex_atomic_cmpxchg_inatomic()