* Re: [PATCH] memblock: stop using implicit alignement to SMP_CACHE_BYTES
[not found] <1538687224-17535-1-git-send-email-rppt@linux.vnet.ibm.com>
@ 2018-10-05 3:25 ` Benjamin Herrenschmidt
2018-10-05 15:05 ` Mike Rapoport
2018-10-05 22:19 ` Andrew Morton
1 sibling, 1 reply; 4+ messages in thread
From: Benjamin Herrenschmidt @ 2018-10-05 3:25 UTC (permalink / raw)
To: Mike Rapoport, linux-mm
Cc: linux-mips, linux-m68k, Michal Hocko, linux-ia64,
Catalin Marinas, Richard Weinberger, Russell King, Ingo Molnar,
Geert Uytterhoeven, Matt Turner, linux-um, Thomas Gleixner,
Guan Xuetao, linux-arm-kernel, Chris Zankel, Michal Simek,
Tony Luck, linux-kernel, Paul Burton, linux-alpha, Andrew Morton,
linuxppc-dev
On Fri, 2018-10-05 at 00:07 +0300, Mike Rapoport wrote:
> When a memblock allocation APIs are called with align = 0, the alignment is
> implicitly set to SMP_CACHE_BYTES.
>
> Replace all such uses of memblock APIs with the 'align' parameter explicitly
> set to SMP_CACHE_BYTES and stop implicit alignment assignment in the
> memblock internal allocation functions.
>
> For the case when memblock APIs are used via helper functions, e.g. like
> iommu_arena_new_node() in Alpha, the helper functions were detected with
> Coccinelle's help and then manually examined and updated where appropriate.
>
> The direct memblock APIs users were updated using the semantic patch below:
What is the purpose of this ? It sounds rather counter-intuitive...
Ben.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] memblock: stop using implicit alignement to SMP_CACHE_BYTES
2018-10-05 3:25 ` [PATCH] memblock: stop using implicit alignement to SMP_CACHE_BYTES Benjamin Herrenschmidt
@ 2018-10-05 15:05 ` Mike Rapoport
0 siblings, 0 replies; 4+ messages in thread
From: Mike Rapoport @ 2018-10-05 15:05 UTC (permalink / raw)
To: Benjamin Herrenschmidt, linux-mm
Cc: linux-mips, Michal Hocko, linux-ia64, Catalin Marinas,
Richard Weinberger, Russell King, Ingo Molnar,
Geert Uytterhoeven, Matt Turner, linux-um, linux-m68k,
Thomas Gleixner, Guan Xuetao, linux-arm-kernel, Chris Zankel,
Michal Simek, Tony Luck, linux-kernel, Paul Burton, linux-alpha,
Andrew Morton, linuxppc-dev
On October 5, 2018 6:25:38 AM GMT+03:00, Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
>On Fri, 2018-10-05 at 00:07 +0300, Mike Rapoport wrote:
>> When a memblock allocation APIs are called with align = 0, the
>alignment is
>> implicitly set to SMP_CACHE_BYTES.
>>
>> Replace all such uses of memblock APIs with the 'align' parameter
>explicitly
>> set to SMP_CACHE_BYTES and stop implicit alignment assignment in the
>> memblock internal allocation functions.
>>
>> For the case when memblock APIs are used via helper functions, e.g.
>like
>> iommu_arena_new_node() in Alpha, the helper functions were detected
>with
>> Coccinelle's help and then manually examined and updated where
>appropriate.
>>
>> The direct memblock APIs users were updated using the semantic patch
>below:
>
>What is the purpose of this ? It sounds rather counter-intuitive...
Why?
I think it actually more intuitive to explicitly set alignment to SMP_CACHE_BYTES rather than use align = 0 because deeply inside allocator it will be implicitly reset to SMP_CACHE_BYTES...
>Ben.
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] memblock: stop using implicit alignement to SMP_CACHE_BYTES
[not found] <1538687224-17535-1-git-send-email-rppt@linux.vnet.ibm.com>
2018-10-05 3:25 ` [PATCH] memblock: stop using implicit alignement to SMP_CACHE_BYTES Benjamin Herrenschmidt
@ 2018-10-05 22:19 ` Andrew Morton
2018-10-11 6:08 ` Mike Rapoport
1 sibling, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2018-10-05 22:19 UTC (permalink / raw)
To: Mike Rapoport
Cc: linux-mm, Catalin Marinas, Chris Zankel, Geert Uytterhoeven,
Guan Xuetao, Ingo Molnar, Matt Turner, Michael Ellerman,
Michal Hocko, Michal Simek, Paul Burton, Richard Weinberger,
Russell King, Thomas Gleixner, Tony Luck, linux-alpha,
linux-arm-kernel, linux-ia64, linux-kernel, linux-m68k,
linux-mips, linuxppc-dev, linux-um
On Fri, 5 Oct 2018 00:07:04 +0300 Mike Rapoport <rppt@linux.vnet.ibm.com> wrote:
> When a memblock allocation APIs are called with align = 0, the alignment is
> implicitly set to SMP_CACHE_BYTES.
>
> Replace all such uses of memblock APIs with the 'align' parameter explicitly
> set to SMP_CACHE_BYTES and stop implicit alignment assignment in the
> memblock internal allocation functions.
>
> For the case when memblock APIs are used via helper functions, e.g. like
> iommu_arena_new_node() in Alpha, the helper functions were detected with
> Coccinelle's help and then manually examined and updated where appropriate.
>
> ...
>
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1298,9 +1298,6 @@ static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
> {
> phys_addr_t found;
>
> - if (!align)
> - align = SMP_CACHE_BYTES;
> -
Can we add a WARN_ON_ONCE(!align) here? To catch unconverted code
which sneaks in later on.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] memblock: stop using implicit alignement to SMP_CACHE_BYTES
2018-10-05 22:19 ` Andrew Morton
@ 2018-10-11 6:08 ` Mike Rapoport
0 siblings, 0 replies; 4+ messages in thread
From: Mike Rapoport @ 2018-10-11 6:08 UTC (permalink / raw)
To: Andrew Morton
Cc: linux-mm, Catalin Marinas, Chris Zankel, Geert Uytterhoeven,
Guan Xuetao, Ingo Molnar, Matt Turner, Michael Ellerman,
Michal Hocko, Michal Simek, Paul Burton, Richard Weinberger,
Russell King, Thomas Gleixner, Tony Luck, linux-alpha,
linux-arm-kernel, linux-ia64, linux-kernel, linux-m68k,
linux-mips, linuxppc-dev, linux-um
On Fri, Oct 05, 2018 at 03:19:34PM -0700, Andrew Morton wrote:
> On Fri, 5 Oct 2018 00:07:04 +0300 Mike Rapoport <rppt@linux.vnet.ibm.com> wrote:
>
> > When a memblock allocation APIs are called with align = 0, the alignment is
> > implicitly set to SMP_CACHE_BYTES.
> >
> > Replace all such uses of memblock APIs with the 'align' parameter explicitly
> > set to SMP_CACHE_BYTES and stop implicit alignment assignment in the
> > memblock internal allocation functions.
> >
> > For the case when memblock APIs are used via helper functions, e.g. like
> > iommu_arena_new_node() in Alpha, the helper functions were detected with
> > Coccinelle's help and then manually examined and updated where appropriate.
> >
> > ...
> >
> > --- a/mm/memblock.c
> > +++ b/mm/memblock.c
> > @@ -1298,9 +1298,6 @@ static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
> > {
> > phys_addr_t found;
> >
> > - if (!align)
> > - align = SMP_CACHE_BYTES;
> > -
>
> Can we add a WARN_ON_ONCE(!align) here? To catch unconverted code
> which sneaks in later on.
Here it goes:
>From baec825c58e8bc11371433d3a4b20b2216877a50 Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@linux.vnet.ibm.com>
Date: Mon, 8 Oct 2018 11:22:10 +0300
Subject: [PATCH] memblock: warn if zero alignment was requested
After update of all memblock users to explicitly specify SMP_CACHE_BYTES
alignment rather than use 0, it is still possible that uncovered users
may sneak in. Add a WARN_ON_ONCE for such cases.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
---
mm/memblock.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/mm/memblock.c b/mm/memblock.c
index 0bbae56..5fefc70 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1298,6 +1298,9 @@ static phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
{
phys_addr_t found;
+ if (WARN_ON_ONCE(!align))
+ align = SMP_CACHE_BYTES;
+
found = memblock_find_in_range_node(size, align, start, end, nid,
flags);
if (found && !memblock_reserve(found, size)) {
@@ -1420,6 +1423,9 @@ static void * __init memblock_alloc_internal(
if (WARN_ON_ONCE(slab_is_available()))
return kzalloc_node(size, GFP_NOWAIT, nid);
+ if (WARN_ON_ONCE(!align))
+ align = SMP_CACHE_BYTES;
+
if (max_addr > memblock.current_limit)
max_addr = memblock.current_limit;
again:
--
2.7.4
--
Sincerely yours,
Mike.
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2018-10-05 3:25 ` [PATCH] memblock: stop using implicit alignement to SMP_CACHE_BYTES Benjamin Herrenschmidt
2018-10-05 15:05 ` Mike Rapoport
2018-10-05 22:19 ` Andrew Morton
2018-10-11 6:08 ` Mike Rapoport
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