* [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps()
@ 2016-01-15 14:20 Grygorii Strashko
2016-01-15 16:56 ` Sebastian Andrzej Siewior
2016-01-20 20:21 ` Sebastian Andrzej Siewior
0 siblings, 2 replies; 5+ messages in thread
From: Grygorii Strashko @ 2016-01-15 14:20 UTC (permalink / raw)
To: bigeasy, Russell King, linux-rt-users
Cc: linux-kernel, linux-arm-kernel, Sekhar Nori, Grygorii Strashko
Now the random crashes are observed on ARM TI am437x-idk-evm used with
-RT Kernel v4.4-rt2 and with Highmem enabled.
The reason of issue is that, newly introduced switch_kmaps() does not
take into account FIX_KMAP_BEGIN, which was re-added by
commit a5f4c561b3b1 ("ARM: 8415/1: early fixmap support for earlycon")
(K4.3) for ARM and since that the value of FIX_KMAP_BEGIN
is not 0 any more.
Hence update switch_kmaps() so it will take into FIX_KMAP_BEGIN while
calculating fixmap idx. This patch also introduces fixmap_idx() to
make code simpler and remove duplicated code.
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/mm/highmem.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index deabc36..542692d 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -34,6 +34,11 @@ static inline pte_t get_fixmap_pte(unsigned long vaddr)
return *ptep;
}
+static unsigned int fixmap_idx(int type)
+{
+ return FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+}
+
void *kmap(struct page *page)
{
might_sleep();
@@ -80,7 +85,7 @@ void *kmap_atomic(struct page *page)
type = kmap_atomic_idx_push();
- idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+ idx = fixmap_idx(type);
vaddr = __fix_to_virt(idx);
#ifdef CONFIG_DEBUG_HIGHMEM
/*
@@ -110,7 +115,7 @@ void __kunmap_atomic(void *kvaddr)
if (kvaddr >= (void *)FIXADDR_START) {
type = kmap_atomic_idx();
- idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+ idx = fixmap_idx(type);
if (cache_is_vivt())
__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
@@ -146,7 +151,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
return page_address(page);
type = kmap_atomic_idx_push();
- idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+ idx = fixmap_idx(type);
vaddr = __fix_to_virt(idx);
#ifdef CONFIG_DEBUG_HIGHMEM
BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
@@ -167,7 +172,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
* Clear @prev's kmap_atomic mappings
*/
for (i = 0; i < prev_p->kmap_idx; i++) {
- int idx = i + KM_TYPE_NR * smp_processor_id();
+ int idx = fixmap_idx(i);
set_fixmap_pte(idx, __pte(0));
}
@@ -175,7 +180,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
* Restore @next_p's kmap_atomic mappings
*/
for (i = 0; i < next_p->kmap_idx; i++) {
- int idx = i + KM_TYPE_NR * smp_processor_id();
+ int idx = fixmap_idx(i);
if (!pte_none(next_p->kmap_pte[i]))
set_fixmap_pte(idx, next_p->kmap_pte[i]);
--
2.7.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps()
2016-01-15 14:20 [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps() Grygorii Strashko
@ 2016-01-15 16:56 ` Sebastian Andrzej Siewior
2016-01-20 20:21 ` Sebastian Andrzej Siewior
1 sibling, 0 replies; 5+ messages in thread
From: Sebastian Andrzej Siewior @ 2016-01-15 16:56 UTC (permalink / raw)
To: Grygorii Strashko
Cc: Russell King, linux-rt-users, linux-kernel, linux-arm-kernel,
Sekhar Nori
* Grygorii Strashko | 2016-01-15 16:20:47 [+0200]:
>Now the random crashes are observed on ARM TI am437x-idk-evm used with
>-RT Kernel v4.4-rt2 and with Highmem enabled.
>
>The reason of issue is that, newly introduced switch_kmaps() does not
>take into account FIX_KMAP_BEGIN, which was re-added by
>commit a5f4c561b3b1 ("ARM: 8415/1: early fixmap support for earlycon")
>(K4.3) for ARM and since that the value of FIX_KMAP_BEGIN
>is not 0 any more.
>
>Hence update switch_kmaps() so it will take into FIX_KMAP_BEGIN while
>calculating fixmap idx. This patch also introduces fixmap_idx() to
>make code simpler and remove duplicated code.
Thank you debugging and fixing this. I will fold this into the initial
patch since it is a v4.1..v4.4 fallout. Regarding your "nobody else be
me" question in the other mail: once I managed something ARM+highmem I
I see this:
|Welcome to Debian GNU/Linux stretch/sid!
|
|[ 11.738637] systemd[1]: Set hostname to <vexpress>.
|[ 11.909949] ------------[ cut here ]------------
|[ 11.909958] kernel BUG at arch/arm/mm/highmem.c:90!
So I did not get as far as a shell to start anything.
>Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
>Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Sebastian
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps()
2016-01-15 14:20 [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps() Grygorii Strashko
2016-01-15 16:56 ` Sebastian Andrzej Siewior
@ 2016-01-20 20:21 ` Sebastian Andrzej Siewior
2016-01-20 20:23 ` Russell King - ARM Linux
1 sibling, 1 reply; 5+ messages in thread
From: Sebastian Andrzej Siewior @ 2016-01-20 20:21 UTC (permalink / raw)
To: Grygorii Strashko
Cc: Russell King, linux-rt-users, linux-kernel, linux-arm-kernel,
Sekhar Nori
* Grygorii Strashko | 2016-01-15 16:20:47 [+0200]:
>--- a/arch/arm/mm/highmem.c
>+++ b/arch/arm/mm/highmem.c
>@@ -175,7 +180,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
> * Restore @next_p's kmap_atomic mappings
> */
> for (i = 0; i < next_p->kmap_idx; i++) {
>- int idx = i + KM_TYPE_NR * smp_processor_id();
>+ int idx = fixmap_idx(i);
>
> if (!pte_none(next_p->kmap_pte[i]))
> set_fixmap_pte(idx, next_p->kmap_pte[i]);
Grygorii, if you remove this chunk then it should apply upstream. Could
you forward it upstream then please? So the -RT piece would shrink a
little:)
Sebastian
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps()
2016-01-20 20:21 ` Sebastian Andrzej Siewior
@ 2016-01-20 20:23 ` Russell King - ARM Linux
2016-01-20 20:35 ` Grygorii Strashko
0 siblings, 1 reply; 5+ messages in thread
From: Russell King - ARM Linux @ 2016-01-20 20:23 UTC (permalink / raw)
To: Sebastian Andrzej Siewior
Cc: Grygorii Strashko, linux-rt-users, linux-kernel,
linux-arm-kernel, Sekhar Nori
On Wed, Jan 20, 2016 at 09:21:39PM +0100, Sebastian Andrzej Siewior wrote:
> * Grygorii Strashko | 2016-01-15 16:20:47 [+0200]:
>
> >--- a/arch/arm/mm/highmem.c
> >+++ b/arch/arm/mm/highmem.c
> >@@ -175,7 +180,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
> > * Restore @next_p's kmap_atomic mappings
> > */
> > for (i = 0; i < next_p->kmap_idx; i++) {
> >- int idx = i + KM_TYPE_NR * smp_processor_id();
> >+ int idx = fixmap_idx(i);
> >
> > if (!pte_none(next_p->kmap_pte[i]))
> > set_fixmap_pte(idx, next_p->kmap_pte[i]);
>
> Grygorii, if you remove this chunk then it should apply upstream. Could
> you forward it upstream then please? So the -RT piece would shrink a
> little:)
Or I could commit my own patch which forms a proportion of this change.
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps()
2016-01-20 20:23 ` Russell King - ARM Linux
@ 2016-01-20 20:35 ` Grygorii Strashko
0 siblings, 0 replies; 5+ messages in thread
From: Grygorii Strashko @ 2016-01-20 20:35 UTC (permalink / raw)
To: Russell King - ARM Linux, Sebastian Andrzej Siewior
Cc: linux-rt-users, linux-kernel, linux-arm-kernel, Sekhar Nori
On 01/20/2016 10:23 PM, Russell King - ARM Linux wrote:
> On Wed, Jan 20, 2016 at 09:21:39PM +0100, Sebastian Andrzej Siewior wrote:
>> * Grygorii Strashko | 2016-01-15 16:20:47 [+0200]:
>>
>>> --- a/arch/arm/mm/highmem.c
>>> +++ b/arch/arm/mm/highmem.c
>>> @@ -175,7 +180,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
>>> * Restore @next_p's kmap_atomic mappings
>>> */
>>> for (i = 0; i < next_p->kmap_idx; i++) {
>>> - int idx = i + KM_TYPE_NR * smp_processor_id();
>>> + int idx = fixmap_idx(i);
>>>
>>> if (!pte_none(next_p->kmap_pte[i]))
>>> set_fixmap_pte(idx, next_p->kmap_pte[i]);
>>
>> Grygorii, if you remove this chunk then it should apply upstream. Could
>> you forward it upstream then please? So the -RT piece would shrink a
>> little:)
>
> Or I could commit my own patch which forms a proportion of this change.
>
np from my side.
--
regards,
-grygorii
^ permalink raw reply [flat|nested] 5+ messages in thread
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2016-01-15 14:20 [4.4-rt2 PATCH] ARM: highmem: take into account FIX_KMAP_BEGIN in switch_kmaps() Grygorii Strashko
2016-01-15 16:56 ` Sebastian Andrzej Siewior
2016-01-20 20:21 ` Sebastian Andrzej Siewior
2016-01-20 20:23 ` Russell King - ARM Linux
2016-01-20 20:35 ` Grygorii Strashko
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