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[POWERPC] Fix deadlock with mmu_hash_lock in hash_page_sync

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hash_page_sync() takes and releases the low level mmu hash
lock in order to sync with other processors disposing of page
tables.  Because that lock can be needed to service hash misses
triggered by interrupt handlers, taking it must be done with
interrupts off.  However, hash_page_sync() appears to be called
with interrupts enabled, thus causing occasional deadlocks.

We fix it by making sure hash_page_sync() masks interrupts while
holding the lock.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Benjamin Herrenschmidt 2008-03-31 07:49:27 +11:00 committed by Paul Mackerras
parent ff3da2e093
commit b991f05f13
1 changed files with 6 additions and 2 deletions
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8
arch/powerpc/mm/hash_low_32.S
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@ -44,6 +44,9 @@ mmu_hash_lock:
#ifdef CONFIG_SMP
.text
_GLOBAL(hash_page_sync)
mfmsr r10
rlwinm r0,r10,0,17,15 /* clear bit 16 (MSR_EE) */
mtmsr r0
lis r8,mmu_hash_lock@h
ori r8,r8,mmu_hash_lock@l
lis r0,0x0fff
@ -60,8 +63,9 @@ _GLOBAL(hash_page_sync)
eieio
li r0,0
stw r0,0(r8)
blr
#endif
mtmsr r10
blr
#endif /* CONFIG_SMP */
/*
* Load a PTE into the hash table, if possible.