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 handler, taking it must be done with
interrupts off. However, hash_page_sync() appear 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 <[EMAIL PROTECTED]>
---
Please test and report asap thought it's probably too late for
2.6.25, it can still go into stable later on.
Index: linux-work/arch/powerpc/mm/hash_low_32.S
===================================================================
--- linux-work.orig/arch/powerpc/mm/hash_low_32.S 2008-03-31
08:42:56.000000000 +1100
+++ linux-work/arch/powerpc/mm/hash_low_32.S 2008-03-31 08:45:05.000000000
+1100
@@ -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,[EMAIL PROTECTED]
ori r8,r8,[EMAIL PROTECTED]
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.
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