On 06/06/2009 11:25 PM, Helge Deller wrote:
John David Anglin wrote:
On the rp3440, the spinlock is definitely needed. With just
preempt_disable/preempt_enable, a crash occurs during bootstrap
at the point unused memory is recovered. Thus, the tlb purge
issue referred to in the preceeding comment affects more than
just N class.
On the otherhand, it doesn't seem necessary to disable interrupts
during the purge with UP kernels.
My kernel crashes happened with UP-kernels on a B2000 (1 CPU).
So, I still have the feeling that it's necessary to disable interrupts
on UP kernels as well.
Hi Dave,
I did further testing. Especially I wanted to clarify if disabling
interrupts are necessary or not.
To test it, I added a WARN_ON(in_interrupt()) to the purge_tlb_start() macro like this:
+#define purge_tlb_start(flags) WARN_ON(in_interrupt()); spin_lock_irqsave(&pa_tlb_lock, flags)
and did ran the compile-test which usually hang my system.
The result is that we really need to disable interrupts.
The WARN_ON() did triggered for me again as it always did hang the system.
This is with a UP-kernel (2.6.30-rc8) on a UP-machine (B2000):
Badness at arch/parisc/kernel/cache.c:461
YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
PSW: 00000000000001101111100100001111 Tainted: G W
r00-03 0006f90f 10640000 10112760 106f4c40
r04-07 5eadc000 2418e30c 0004eadc 113336f0
r08-11 2418e31c 0000007c 106f4a88 7c5b3c7c
r12-15 104c45ec 106c9da0 00001000 10000000
r16-19 00000fff 1067f13c 105e0560 00000100
r20-23 0000ff00 5eadc10a 5eadc100 00000040
r24-27 00000000 5eadcfc0 5eadd000 10640680
r28-31 106f4000 0000000a 106f4c80 471249e8
sr00-03 00000000 00000000 00000000 00000025
sr04-07 00000000 00000000 00000000 00000000
IASQ: 00000000 00000000 IAOQ: 10112774 10112778
IIR: 03ffe01f ISR: 0424013a IOR: b72dcfc0
CPU: 0 CR30: 106f4000 CR31: 11111111
ORIG_R28: 106f4dc0
IAOQ[0]: flush_kernel_dcache_page_addr+0x30/0xa0
IAOQ[1]: flush_kernel_dcache_page_addr+0x34/0xa0
RP(r2): flush_kernel_dcache_page_addr+0x1c/0xa0
Backtrace:
[<10112760>] flush_kernel_dcache_page_addr+0x1c/0xa0
Sadly I didn't got a full backtrace.
The WARN_ON() triggered around 20 times during the phase where my machine was
pretty much loaded.
Interestingly it was always inflush_kernel_dcache_page_addr().
So, I still think my patch at http://patchwork.kernel.org/patch/28458/ should
be applied to all kernels.
Helge
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