Re: [PATCH 2/2] powerpc/mm/memtrace: Let the arch hotunplug code flush cache

[Balbir Singh]

On Wed, Apr 11, 2018 at 9:05 PM, Michael Ellerman  wrote:
> Balbir Singh  writes:
>
>> Don't do this via custom code, instead now that we have support
>> in the arch hotplug/hotunplug code, rely on those routines
>> to do the right thing.
>>
>> Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in 
>> memory tracing")
>
> That's not really right.
>
> This patch doesn't fix it, the previous patch did.
>
> If I just backport this patch then it's still broken.
>
> So I'll tag patch 1 with the above Fixes: tag and add stable, and then
> this just becomes a cleanup.
>

Fair point, the previous one does indeed fix things. I can do a minimal backport
fixing .size to .line_size if needed.

Cheers,
Balbir

Re: [PATCH 2/2] powerpc/mm/memtrace: Let the arch hotunplug code flush cache

[Michael Ellerman]

Balbir Singh  writes:

> Don't do this via custom code, instead now that we have support
> in the arch hotplug/hotunplug code, rely on those routines
> to do the right thing.
>
> Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in memory 
> tracing")

That's not really right.

This patch doesn't fix it, the previous patch did.

If I just backport this patch then it's still broken.

So I'll tag patch 1 with the above Fixes: tag and add stable, and then
this just becomes a cleanup.

OK?

cheers

> diff --git a/arch/powerpc/platforms/powernv/memtrace.c 
> b/arch/powerpc/platforms/powernv/memtrace.c
> index de470caf0784..fc222a0c2ac4 100644
> --- a/arch/powerpc/platforms/powernv/memtrace.c
> +++ b/arch/powerpc/platforms/powernv/memtrace.c
> @@ -82,19 +82,6 @@ static const struct file_operations memtrace_fops = {
>   .open   = simple_open,
>  };
>  
> -static void flush_memory_region(u64 base, u64 size)
> -{
> - unsigned long line_size = ppc64_caches.l1d.size;
> - u64 end = base + size;
> - u64 addr;
> -
> - base = round_down(base, line_size);
> - end = round_up(end, line_size);
> -
> - for (addr = base; addr < end; addr += line_size)
> - asm volatile("dcbf 0,%0" : "=r" (addr) :: "memory");
> -}
> -
>  static int check_memblock_online(struct memory_block *mem, void *arg)
>  {
>   if (mem->state != MEM_ONLINE)
> @@ -132,10 +119,6 @@ static bool memtrace_offline_pages(u32 nid, u64 
> start_pfn, u64 nr_pages)
>   walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
> change_memblock_state);
>  
> - /* RCU grace period? */
> - flush_memory_region((u64)__va(start_pfn << PAGE_SHIFT),
> - nr_pages << PAGE_SHIFT);
> -
>   lock_device_hotplug();
>   remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
>   unlock_device_hotplug();
> -- 
> 2.13.6

Re: [PATCH 2/2] powerpc/mm/memtrace: Let the arch hotunplug code flush cache

[rashmica]

On 06/04/18 15:24, Balbir Singh wrote:
> Don't do this via custom code, instead now that we have support
> in the arch hotplug/hotunplug code, rely on those routines
> to do the right thing.
>
> Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in memory 
> tracing")
> because the older code uses ppc64_caches.l1d.size instead of
> ppc64_caches.l1d.line_size
>
> Signed-off-by: Balbir Singh 

Reviewed-by: Rashmica Gupta 

[PATCH 2/2] powerpc/mm/memtrace: Let the arch hotunplug code flush cache

[Balbir Singh]

Don't do this via custom code, instead now that we have support
in the arch hotplug/hotunplug code, rely on those routines
to do the right thing.

Fixes: 9d5171a8f248 ("powerpc/powernv: Enable removal of memory for in memory 
tracing")
because the older code uses ppc64_caches.l1d.size instead of
ppc64_caches.l1d.line_size

Signed-off-by: Balbir Singh 
---
 arch/powerpc/platforms/powernv/memtrace.c | 17 -
 1 file changed, 17 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/memtrace.c 
b/arch/powerpc/platforms/powernv/memtrace.c
index de470caf0784..fc222a0c2ac4 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -82,19 +82,6 @@ static const struct file_operations memtrace_fops = {
.open   = simple_open,
 };
 
-static void flush_memory_region(u64 base, u64 size)
-{
-   unsigned long line_size = ppc64_caches.l1d.size;
-   u64 end = base + size;
-   u64 addr;
-
-   base = round_down(base, line_size);
-   end = round_up(end, line_size);
-
-   for (addr = base; addr < end; addr += line_size)
-   asm volatile("dcbf 0,%0" : "=r" (addr) :: "memory");
-}
-
 static int check_memblock_online(struct memory_block *mem, void *arg)
 {
if (mem->state != MEM_ONLINE)
@@ -132,10 +119,6 @@ static bool memtrace_offline_pages(u32 nid, u64 start_pfn, 
u64 nr_pages)
walk_memory_range(start_pfn, end_pfn, (void *)MEM_OFFLINE,
  change_memblock_state);
 
-   /* RCU grace period? */
-   flush_memory_region((u64)__va(start_pfn << PAGE_SHIFT),
-   nr_pages << PAGE_SHIFT);
-
lock_device_hotplug();
remove_memory(nid, start_pfn << PAGE_SHIFT, nr_pages << PAGE_SHIFT);
unlock_device_hotplug();
-- 
2.13.6