Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Tony Lindgren]

Hi,

Looks like this patch causes a boot regression at least for Cortex-A15.
That's commit 990e6d0e1de8 ("arm: extend pfn_valid to take into accound
freed memory map alignment") in Linux next.

Most of the time I see the following on beagle-x15 right after init starts:

Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
CPU0: stopping
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.13.0-rc7-next-20210625 #100
Hardware name: Generic DRA74X (Flattened Device Tree)
[<c0110c54>] (unwind_backtrace) from [<c010b408>] (show_stack+0x10/0x14)
[<c010b408>] (show_stack) from [<c09fae04>] (dump_stack_lvl+0x40/0x4c)
[<c09fae04>] (dump_stack_lvl) from [<c010e768>] (do_handle_IPI+0x2c8/0x334)
[<c010e768>] (do_handle_IPI) from [<c010e7e8>] (ipi_handler+0x14/0x20)
[<c010e7e8>] (ipi_handler) from [<c01a5f14>] (handle_percpu_devid_irq+0xa8/0x22c)
[<c01a5f14>] (handle_percpu_devid_irq) from [<c019fc78>] (handle_domain_irq+0x64/0xa4)
[<c019fc78>] (handle_domain_irq) from [<c05b9bdc>] (gic_handle_irq+0x88/0xb0)
[<c05b9bdc>] (gic_handle_irq) from [<c0100b6c>] (__irq_svc+0x6c/0x90)
Exception stack(0xc0f01f08 to 0xc0f01f50)
1f00:                   00000f38 00000f37 00000000 fe600000 c0ff90c0 00000000
1f20: c0f0520c c0f05260 00000000 c0f00000 00000000 c0e788f0 00000000 c0f01f58
1f40: c0126aa0 c0107dc4 60000013 ffffffff
[<c0100b6c>] (__irq_svc) from [<c0107dc4>] (arch_cpu_idle+0x1c/0x3c)
[<c0107dc4>] (arch_cpu_idle) from [<c0a098d8>] (default_idle_call+0x38/0xe0)
[<c0a098d8>] (default_idle_call) from [<c0172860>] (do_idle+0x214/0x2cc)
[<c0172860>] (do_idle) from [<c0172c0c>] (cpu_startup_entry+0x18/0x1c)
[<c0172c0c>] (cpu_startup_entry) from [<c0e00ef8>] (start_kernel+0x5cc/0x6c4)

Sometimes the system boots to console, but maybe only about 20% of the
time. Reverting 990e6d0e1de8 makes Linux next boot again for me.

Regards,

Tony

#regzb introduced: 990e6d0e1de8 ("arm: extend pfn_valid to take into accound freed memory map alignment")


* Mike Rapoport <rppt@kernel.org> [700101 02:00]:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> When unused memory map is freed the preserved part of the memory map is
> extended to match pageblock boundaries because lots of core mm
> functionality relies on homogeneity of the memory map within pageblock
> boundaries.
> 
> Since pfn_valid() is used to check whether there is a valid memory map
> entry for a PFN, make it return true also for PFNs that have memory map
> entries even if there is no actual memory populated there.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
>  arch/arm/mm/init.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 9d4744a632c6..6162a070a410 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -125,11 +125,22 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
>  int pfn_valid(unsigned long pfn)
>  {
>  	phys_addr_t addr = __pfn_to_phys(pfn);
> +	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
>  
>  	if (__phys_to_pfn(addr) != pfn)
>  		return 0;
>  
> -	return memblock_is_map_memory(addr);
> +	/*
> +	 * If address less than pageblock_size bytes away from a present
> +	 * memory chunk there still will be a memory map entry for it
> +	 * because we round freed memory map to the pageblock boundaries.
> +	 */
> +	if (memblock_overlaps_region(&memblock.memory,
> +				     ALIGN_DOWN(addr, pageblock_size),
> +				     pageblock_size))
> +		return 1;
> +
> +	return 0;
>  }
>  EXPORT_SYMBOL(pfn_valid);
>  #endif
> -- 
> 2.28.0
> 

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Mike Rapoport]

Hi Tony,

On Mon, Jun 28, 2021 at 01:20:11PM +0300, Tony Lindgren wrote:
> Hi,
> 
> Looks like this patch causes a boot regression at least for Cortex-A15.
> That's commit 990e6d0e1de8 ("arm: extend pfn_valid to take into accound
> freed memory map alignment") in Linux next.
> 
> Most of the time I see the following on beagle-x15 right after init starts:
> 
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> CPU0: stopping
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.13.0-rc7-next-20210625 #100
> Hardware name: Generic DRA74X (Flattened Device Tree)
> [<c0110c54>] (unwind_backtrace) from [<c010b408>] (show_stack+0x10/0x14)
> [<c010b408>] (show_stack) from [<c09fae04>] (dump_stack_lvl+0x40/0x4c)
> [<c09fae04>] (dump_stack_lvl) from [<c010e768>] (do_handle_IPI+0x2c8/0x334)
> [<c010e768>] (do_handle_IPI) from [<c010e7e8>] (ipi_handler+0x14/0x20)
> [<c010e7e8>] (ipi_handler) from [<c01a5f14>] (handle_percpu_devid_irq+0xa8/0x22c)
> [<c01a5f14>] (handle_percpu_devid_irq) from [<c019fc78>] (handle_domain_irq+0x64/0xa4)
> [<c019fc78>] (handle_domain_irq) from [<c05b9bdc>] (gic_handle_irq+0x88/0xb0)
> [<c05b9bdc>] (gic_handle_irq) from [<c0100b6c>] (__irq_svc+0x6c/0x90)
> Exception stack(0xc0f01f08 to 0xc0f01f50)
> 1f00:                   00000f38 00000f37 00000000 fe600000 c0ff90c0 00000000
> 1f20: c0f0520c c0f05260 00000000 c0f00000 00000000 c0e788f0 00000000 c0f01f58
> 1f40: c0126aa0 c0107dc4 60000013 ffffffff
> [<c0100b6c>] (__irq_svc) from [<c0107dc4>] (arch_cpu_idle+0x1c/0x3c)
> [<c0107dc4>] (arch_cpu_idle) from [<c0a098d8>] (default_idle_call+0x38/0xe0)
> [<c0a098d8>] (default_idle_call) from [<c0172860>] (do_idle+0x214/0x2cc)
> [<c0172860>] (do_idle) from [<c0172c0c>] (cpu_startup_entry+0x18/0x1c)
> [<c0172c0c>] (cpu_startup_entry) from [<c0e00ef8>] (start_kernel+0x5cc/0x6c4)
> 
> Sometimes the system boots to console, but maybe only about 20% of the
> time. Reverting 990e6d0e1de8 makes Linux next boot again for me.

Can you please send log with 'memblock=debug' added to the command line?
 
> Regards,
> 
> Tony
> 
> #regzb introduced: 990e6d0e1de8 ("arm: extend pfn_valid to take into accound freed memory map alignment")
> 
> 
> * Mike Rapoport <rppt@kernel.org> [700101 02:00]:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> > 
> > When unused memory map is freed the preserved part of the memory map is
> > extended to match pageblock boundaries because lots of core mm
> > functionality relies on homogeneity of the memory map within pageblock
> > boundaries.
> > 
> > Since pfn_valid() is used to check whether there is a valid memory map
> > entry for a PFN, make it return true also for PFNs that have memory map
> > entries even if there is no actual memory populated there.
> > 
> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> > ---
> >  arch/arm/mm/init.c | 13 ++++++++++++-
> >  1 file changed, 12 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> > index 9d4744a632c6..6162a070a410 100644
> > --- a/arch/arm/mm/init.c
> > +++ b/arch/arm/mm/init.c
> > @@ -125,11 +125,22 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
> >  int pfn_valid(unsigned long pfn)
> >  {
> >  	phys_addr_t addr = __pfn_to_phys(pfn);
> > +	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
> >  
> >  	if (__phys_to_pfn(addr) != pfn)
> >  		return 0;
> >  
> > -	return memblock_is_map_memory(addr);
> > +	/*
> > +	 * If address less than pageblock_size bytes away from a present
> > +	 * memory chunk there still will be a memory map entry for it
> > +	 * because we round freed memory map to the pageblock boundaries.
> > +	 */
> > +	if (memblock_overlaps_region(&memblock.memory,
> > +				     ALIGN_DOWN(addr, pageblock_size),
> > +				     pageblock_size))
> > +		return 1;
> > +
> > +	return 0;
> >  }
> >  EXPORT_SYMBOL(pfn_valid);
> >  #endif
> > -- 
> > 2.28.0
> > 

-- 
Sincerely yours,
Mike.

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Tony Lindgren]

* Mike Rapoport <rppt@linux.ibm.com> [210628 14:07]:
> Can you please send log with 'memblock=debug' added to the command line?

Sure, log now available at:

http://muru.com/beagle-x15.txt

Regards,

Tony

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Mike Rapoport]

On Mon, Jun 28, 2021 at 06:26:26PM +0300, Tony Lindgren wrote:
> * Mike Rapoport <rppt@linux.ibm.com> [210628 14:07]:
> > Can you please send log with 'memblock=debug' added to the command line?
> 
> Sure, log now available at:
> 
> http://muru.com/beagle-x15.txt

Hmm, no clues yet :(

Do you have CONFIG_DEBUG_VM, CONFIG_DEBUG_VM_PGFLAGS and
CONFIG_PAGE_POISONING enabled in your config?
If not, can you please enable them and see if any of VM_BUG_* triggers?

Do you use FLATMEM or SPARSEMEM in your config?

Let's try seeing what PFNs get false results from pfn_valid, maybe this
will give a better lead.

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 6162a070a410..66985fc3e730 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -126,10 +126,16 @@ int pfn_valid(unsigned long pfn)
 {
 	phys_addr_t addr = __pfn_to_phys(pfn);
 	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
+	bool overlaps = memblock_overlaps_region(&memblock.memory,
+				     ALIGN_DOWN(addr, pageblock_size),
+				     pageblock_size);
 
 	if (__phys_to_pfn(addr) != pfn)
 		return 0;
 
+	if (memblock_is_map_memory(addr) != overlaps)
+		pr_info("%s(%pS): pfn: %lx: is_map: %d overlaps: %d\n", __func__, (void *)_RET_IP_, pfn, memblock_is_map_memory(addr), overlaps);
+
 	/*
 	 * If address less than pageblock_size bytes away from a present
 	 * memory chunk there still will be a memory map entry for it

-- 
Sincerely yours,
Mike.

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Tony Lindgren]

Hi,

* Mike Rapoport <rppt@linux.ibm.com> [210629 05:33]:
> On Mon, Jun 28, 2021 at 06:26:26PM +0300, Tony Lindgren wrote:
> > * Mike Rapoport <rppt@linux.ibm.com> [210628 14:07]:
> > > Can you please send log with 'memblock=debug' added to the command line?
> > 
> > Sure, log now available at:
> > 
> > http://muru.com/beagle-x15.txt
> 
> Hmm, no clues yet :(
> 
> Do you have CONFIG_DEBUG_VM, CONFIG_DEBUG_VM_PGFLAGS and
> CONFIG_PAGE_POISONING enabled in your config?
> If not, can you please enable them and see if any of VM_BUG_* triggers?

OK enabled, and no errors or warnings are triggered.

> Do you use FLATMEM or SPARSEMEM in your config?

Looks like make omap2plus_defconfig enables FLATMEM:

$ grep -e SPARSEMEM -e FLATMEM .config
CONFIG_ARCH_FLATMEM_ENABLE=y
CONFIG_ARCH_SPARSEMEM_ENABLE=y
CONFIG_FLATMEM_MANUAL=y
# CONFIG_SPARSEMEM_MANUAL is not set
CONFIG_FLATMEM=y

> Let's try seeing what PFNs get false results from pfn_valid, maybe this
> will give a better lead.

With your patch below, system boots with lots of the following:

[   13.058654] Freeing unused kernel image (initmem) memory: 1024K
...
[   13.129211] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffb6: is_map: 1 overlaps: 0
[   13.137481] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffb7: is_map: 1 overlaps: 0
[   13.145751] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffb8: is_map: 1 overlaps: 0
[   13.153991] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffb9: is_map: 1 overlaps: 0
[   13.162200] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffba: is_map: 1 overlaps: 0
[   13.170440] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffbb: is_map: 1 overlaps: 0
[   13.178680] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffbc: is_map: 1 overlaps: 0
[   13.186920] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffbd: is_map: 1 overlaps: 0
[   13.195159] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffbe: is_map: 1 overlaps: 0
[   13.203399] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffbf: is_map: 1 overlaps: 0
[   13.211639] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fff00: is_map: 1 overlaps: 0
...

Then changing console loglevel to 0 boots system to login prompt. But I'm
seeing some init processes segfaulting during start-up.

Regards,

Tony


> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 6162a070a410..66985fc3e730 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -126,10 +126,16 @@ int pfn_valid(unsigned long pfn)
>  {
>  	phys_addr_t addr = __pfn_to_phys(pfn);
>  	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
> +	bool overlaps = memblock_overlaps_region(&memblock.memory,
> +				     ALIGN_DOWN(addr, pageblock_size),
> +				     pageblock_size);
>  
>  	if (__phys_to_pfn(addr) != pfn)
>  		return 0;
>  
> +	if (memblock_is_map_memory(addr) != overlaps)
> +		pr_info("%s(%pS): pfn: %lx: is_map: %d overlaps: %d\n", __func__, (void *)_RET_IP_, pfn, memblock_is_map_memory(addr), overlaps);
> +
>  	/*
>  	 * If address less than pageblock_size bytes away from a present
>  	 * memory chunk there still will be a memory map entry for it
> 
> -- 
> Sincerely yours,
> Mike.

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Mike Rapoport]

Hi,

On Tue, Jun 29, 2021 at 11:54:02AM +0300, Tony Lindgren wrote:
> Hi,
> 
> * Mike Rapoport <rppt@linux.ibm.com> [210629 05:33]:
> > On Mon, Jun 28, 2021 at 06:26:26PM +0300, Tony Lindgren wrote:
> > > * Mike Rapoport <rppt@linux.ibm.com> [210628 14:07]:
> > > > Can you please send log with 'memblock=debug' added to the command line?
> > > 
> > > Sure, log now available at:
> > > 
> > > http://muru.com/beagle-x15.txt
> > 
> > Hmm, no clues yet :(
> > 
> > Do you have CONFIG_DEBUG_VM, CONFIG_DEBUG_VM_PGFLAGS and
> > CONFIG_PAGE_POISONING enabled in your config?
> > If not, can you please enable them and see if any of VM_BUG_* triggers?
> 
> OK enabled, and no errors or warnings are triggered.
> 
> > Do you use FLATMEM or SPARSEMEM in your config?
> 
> Looks like make omap2plus_defconfig enables FLATMEM:
> 
> $ grep -e SPARSEMEM -e FLATMEM .config
> CONFIG_ARCH_FLATMEM_ENABLE=y
> CONFIG_ARCH_SPARSEMEM_ENABLE=y
> CONFIG_FLATMEM_MANUAL=y
> # CONFIG_SPARSEMEM_MANUAL is not set
> CONFIG_FLATMEM=y
> 
> > Let's try seeing what PFNs get false results from pfn_valid, maybe this
> > will give a better lead.
> 
> With your patch below, system boots with lots of the following:
> 
> [   13.058654] Freeing unused kernel image (initmem) memory: 1024K
> ...
> [   13.129211] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffb6: is_map: 1 overlaps: 0
> [   13.137481] pfn_valid(__sync_icache_dcache+0x2c/0x138): pfn: fffb7: is_map: 1 overlaps: 0

...

> Then changing console loglevel to 0 boots system to login prompt. But I'm
> seeing some init processes segfaulting during start-up.

As it seems, the new version of pfn_valid() decides that last pages are not
valid because of the overflow in memblock_overlaps_region(). As the result,
__sync_icache_dcache() skips flushing these pages.

The patch below should fix this. I've left the prints for now, hopefully
they will not appear anymore. 

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 6162a070a410..7ba22d23eca4 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -126,10 +126,16 @@ int pfn_valid(unsigned long pfn)
 {
 	phys_addr_t addr = __pfn_to_phys(pfn);
 	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
+	bool overlaps = memblock_overlaps_region(&memblock.memory,
+				     ALIGN_DOWN(addr, pageblock_size),
+				     pageblock_size - 1);
 
 	if (__phys_to_pfn(addr) != pfn)
 		return 0;
 
+	if (memblock_is_map_memory(addr) != overlaps)
+		pr_info("%s(%pS): pfn: %lx: is_map: %d overlaps: %d\n", __func__, (void *)_RET_IP_, pfn, memblock_is_map_memory(addr), overlaps);
+
 	/*
 	 * If address less than pageblock_size bytes away from a present
 	 * memory chunk there still will be a memory map entry for it
@@ -137,7 +143,7 @@ int pfn_valid(unsigned long pfn)
 	 */
 	if (memblock_overlaps_region(&memblock.memory,
 				     ALIGN_DOWN(addr, pageblock_size),
-				     pageblock_size))
+				     pageblock_size - 1))
 		return 1;
 
 	return 0;
 
-- 
Sincerely yours,
Mike.

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Tony Lindgren]

* Mike Rapoport <rppt@linux.ibm.com> [210629 10:51]:
> As it seems, the new version of pfn_valid() decides that last pages are not
> valid because of the overflow in memblock_overlaps_region(). As the result,
> __sync_icache_dcache() skips flushing these pages.
> 
> The patch below should fix this. I've left the prints for now, hopefully
> they will not appear anymore. 

Yes this allows the system to boot for me :)

I'm still seeing these three prints though:

...
smp: Brought up 1 node, 2 CPUs
SMP: Total of 2 processors activated (3994.41 BogoMIPS).
CPU: All CPU(s) started in SVC mode.
pfn_valid(__pageblock_pfn_to_page+0x14/0xa8): pfn: afe00: is_map: 0 overlaps: 1
pfn_valid(__pageblock_pfn_to_page+0x28/0xa8): pfn: affff: is_map: 0 overlaps: 1
pfn_valid(__pageblock_pfn_to_page+0x38/0xa8): pfn: afe00: is_map: 0 overlaps: 1
devtmpfs: initialized
...

Regards,

Tony


> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 6162a070a410..7ba22d23eca4 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -126,10 +126,16 @@ int pfn_valid(unsigned long pfn)
>  {
>  	phys_addr_t addr = __pfn_to_phys(pfn);
>  	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
> +	bool overlaps = memblock_overlaps_region(&memblock.memory,
> +				     ALIGN_DOWN(addr, pageblock_size),
> +				     pageblock_size - 1);
>  
>  	if (__phys_to_pfn(addr) != pfn)
>  		return 0;
>  
> +	if (memblock_is_map_memory(addr) != overlaps)
> +		pr_info("%s(%pS): pfn: %lx: is_map: %d overlaps: %d\n", __func__, (void *)_RET_IP_, pfn, memblock_is_map_memory(addr), overlaps);
> +
>  	/*
>  	 * If address less than pageblock_size bytes away from a present
>  	 * memory chunk there still will be a memory map entry for it
> @@ -137,7 +143,7 @@ int pfn_valid(unsigned long pfn)
>  	 */
>  	if (memblock_overlaps_region(&memblock.memory,
>  				     ALIGN_DOWN(addr, pageblock_size),
> -				     pageblock_size))
> +				     pageblock_size - 1))
>  		return 1;
>  
>  	return 0;
>  
> -- 
> Sincerely yours,
> Mike.

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Mike Rapoport]

On Tue, Jun 29, 2021 at 02:52:39PM +0300, Tony Lindgren wrote:
> * Mike Rapoport <rppt@linux.ibm.com> [210629 10:51]:
> > As it seems, the new version of pfn_valid() decides that last pages are not
> > valid because of the overflow in memblock_overlaps_region(). As the result,
> > __sync_icache_dcache() skips flushing these pages.
> > 
> > The patch below should fix this. I've left the prints for now, hopefully
> > they will not appear anymore. 
> 
> Yes this allows the system to boot for me :)
> 
> I'm still seeing these three prints though:
> 
> ...
> smp: Brought up 1 node, 2 CPUs
> SMP: Total of 2 processors activated (3994.41 BogoMIPS).
> CPU: All CPU(s) started in SVC mode.
> pfn_valid(__pageblock_pfn_to_page+0x14/0xa8): pfn: afe00: is_map: 0 overlaps: 1
> pfn_valid(__pageblock_pfn_to_page+0x28/0xa8): pfn: affff: is_map: 0 overlaps: 1
> pfn_valid(__pageblock_pfn_to_page+0x38/0xa8): pfn: afe00: is_map: 0 overlaps: 1

These pfns do have memory map despite they are stolen in
arm_memblock_steal():

memblock_free: [0xaff00000-0xafffffff] arm_memblock_steal+0x50/0x70
memblock_remove: [0xaff00000-0xafffffff] arm_memblock_steal+0x5c/0x70
...
memblock_free: [0xafe00000-0xafefffff] arm_memblock_steal+0x50/0x70
memblock_remove: [0xafe00000-0xafefffff] arm_memblock_steal+0x5c/0x70

But the struct pages there are never initialized.

I'll resend v3 of the entire set with an addition patch to take care of
that as well.

> devtmpfs: initialized
> ...
> 
> Regards,
> 
> Tony
> 
> 
> > diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> > index 6162a070a410..7ba22d23eca4 100644
> > --- a/arch/arm/mm/init.c
> > +++ b/arch/arm/mm/init.c
> > @@ -126,10 +126,16 @@ int pfn_valid(unsigned long pfn)
> >  {
> >  	phys_addr_t addr = __pfn_to_phys(pfn);
> >  	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
> > +	bool overlaps = memblock_overlaps_region(&memblock.memory,
> > +				     ALIGN_DOWN(addr, pageblock_size),
> > +				     pageblock_size - 1);
> >  
> >  	if (__phys_to_pfn(addr) != pfn)
> >  		return 0;
> >  
> > +	if (memblock_is_map_memory(addr) != overlaps)
> > +		pr_info("%s(%pS): pfn: %lx: is_map: %d overlaps: %d\n", __func__, (void *)_RET_IP_, pfn, memblock_is_map_memory(addr), overlaps);
> > +
> >  	/*
> >  	 * If address less than pageblock_size bytes away from a present
> >  	 * memory chunk there still will be a memory map entry for it
> > @@ -137,7 +143,7 @@ int pfn_valid(unsigned long pfn)
> >  	 */
> >  	if (memblock_overlaps_region(&memblock.memory,
> >  				     ALIGN_DOWN(addr, pageblock_size),
> > -				     pageblock_size))
> > +				     pageblock_size - 1))
> >  		return 1;
> >  
> >  	return 0;
> >  
> > -- 
> > Sincerely yours,
> > Mike.

-- 
Sincerely yours,
Mike.

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Tony Lindgren]

* Mike Rapoport <rppt@linux.ibm.com> [210629 12:50]:
> On Tue, Jun 29, 2021 at 02:52:39PM +0300, Tony Lindgren wrote:
> > * Mike Rapoport <rppt@linux.ibm.com> [210629 10:51]:
> > > As it seems, the new version of pfn_valid() decides that last pages are not
> > > valid because of the overflow in memblock_overlaps_region(). As the result,
> > > __sync_icache_dcache() skips flushing these pages.
> > > 
> > > The patch below should fix this. I've left the prints for now, hopefully
> > > they will not appear anymore. 
> > 
> > Yes this allows the system to boot for me :)
> > 
> > I'm still seeing these three prints though:
> > 
> > ...
> > smp: Brought up 1 node, 2 CPUs
> > SMP: Total of 2 processors activated (3994.41 BogoMIPS).
> > CPU: All CPU(s) started in SVC mode.
> > pfn_valid(__pageblock_pfn_to_page+0x14/0xa8): pfn: afe00: is_map: 0 overlaps: 1
> > pfn_valid(__pageblock_pfn_to_page+0x28/0xa8): pfn: affff: is_map: 0 overlaps: 1
> > pfn_valid(__pageblock_pfn_to_page+0x38/0xa8): pfn: afe00: is_map: 0 overlaps: 1
> 
> These pfns do have memory map despite they are stolen in
> arm_memblock_steal():
> 
> memblock_free: [0xaff00000-0xafffffff] arm_memblock_steal+0x50/0x70
> memblock_remove: [0xaff00000-0xafffffff] arm_memblock_steal+0x5c/0x70
> ...
> memblock_free: [0xafe00000-0xafefffff] arm_memblock_steal+0x50/0x70
> memblock_remove: [0xafe00000-0xafefffff] arm_memblock_steal+0x5c/0x70
> 
> But the struct pages there are never initialized.
> 
> I'll resend v3 of the entire set with an addition patch to take care of
> that as well.

OK sounds good to me :)

Thanks,

Tony

Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

[Mike Rapoport]

On Tue, Jun 29, 2021 at 03:50:23PM +0300, Mike Rapoport wrote:
> On Tue, Jun 29, 2021 at 02:52:39PM +0300, Tony Lindgren wrote:
> > * Mike Rapoport <rppt@linux.ibm.com> [210629 10:51]:
> > > As it seems, the new version of pfn_valid() decides that last pages are not
> > > valid because of the overflow in memblock_overlaps_region(). As the result,
> > > __sync_icache_dcache() skips flushing these pages.
> > > 
> > > The patch below should fix this. I've left the prints for now, hopefully
> > > they will not appear anymore. 
> > 
> > Yes this allows the system to boot for me :)
> > 
> > I'm still seeing these three prints though:
> > 
> > ...
> > smp: Brought up 1 node, 2 CPUs
> > SMP: Total of 2 processors activated (3994.41 BogoMIPS).
> > CPU: All CPU(s) started in SVC mode.
> > pfn_valid(__pageblock_pfn_to_page+0x14/0xa8): pfn: afe00: is_map: 0 overlaps: 1
> > pfn_valid(__pageblock_pfn_to_page+0x28/0xa8): pfn: affff: is_map: 0 overlaps: 1
> > pfn_valid(__pageblock_pfn_to_page+0x38/0xa8): pfn: afe00: is_map: 0 overlaps: 1
> 
> These pfns do have memory map despite they are stolen in
> arm_memblock_steal():
> 
> memblock_free: [0xaff00000-0xafffffff] arm_memblock_steal+0x50/0x70
> memblock_remove: [0xaff00000-0xafffffff] arm_memblock_steal+0x5c/0x70
> ...
> memblock_free: [0xafe00000-0xafefffff] arm_memblock_steal+0x50/0x70
> memblock_remove: [0xafe00000-0xafefffff] arm_memblock_steal+0x5c/0x70
> 
> But the struct pages there are never initialized.

Actually, with FLATMEM these struct pages will be always set to 0 because
we don't do memory map poisoning with FLATMEM.

I could not find a case where zeroed struct page would cause real trouble,
so I'd say it is more theoretical issue and it can be addressed unrelated
to these changes.

-- 
Sincerely yours,
Mike.