* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
@ 2020-09-12 10:45 ` Mike Rapoport
0 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-09-12 10:45 UTC (permalink / raw)
To: Atish Patra
Cc: linux-kernel, Albert Ou, Anup Patel, linux-riscv, Palmer Dabbelt,
Paul Walmsley, Zong Li
Hello Atish,
On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> Currently, any usable memory area beyond page_offset is removed by adding the
> memory sizes from each memblock. That may not work for sparse memory
> as memory regions can be very far apart resulting incorrect removal of some
> usable memory.
If I understand correctly, the memory with physical addresses larger
than (-PAGE_OFFSET) cannot be used. Since it was aready
memblock_add()'ed during device tree parsing, you need to remove it from
memblock.
For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
> Just use the start of the first memory block and the end of the last memory
> block to compute the size of the total memory that can be used.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
> arch/riscv/mm/init.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 787c75f751a5..188281fc2816 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> {
> struct memblock_region *reg;
> phys_addr_t mem_size = 0;
> - phys_addr_t total_mem = 0;
> phys_addr_t mem_start, end = 0;
> phys_addr_t vmlinux_end = __pa_symbol(&_end);
> phys_addr_t vmlinux_start = __pa_symbol(&_start);
> @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> /* Find the memory region containing the kernel */
> for_each_memblock(memory, reg) {
> end = reg->base + reg->size;
> - if (!total_mem)
> + if (!mem_start)
> mem_start = reg->base;
> if (reg->base <= vmlinux_start && vmlinux_end <= end)
> BUG_ON(reg->size == 0);
> - total_mem = total_mem + reg->size;
> }
>
> /*
> * Remove memblock from the end of usable area to the
> * end of region
> */
> - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> if (mem_start + mem_size < end)
> memblock_remove(mem_start + mem_size,
> end - mem_start - mem_size);
> --
> 2.24.0
>
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
2020-09-12 10:45 ` Mike Rapoport
@ 2020-09-13 23:47 ` Atish Patra
-1 siblings, 0 replies; 12+ messages in thread
From: Atish Patra @ 2020-09-13 23:47 UTC (permalink / raw)
To: Mike Rapoport, Anup Patel, Anup Patel
Cc: Albert Ou, linux-kernel@vger.kernel.org List, Atish Patra,
Palmer Dabbelt, Zong Li, Paul Walmsley, linux-riscv
On Sat, Sep 12, 2020 at 3:45 AM Mike Rapoport <rppt@kernel.org> wrote:
>
> Hello Atish,
>
> On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > Currently, any usable memory area beyond page_offset is removed by adding the
> > memory sizes from each memblock. That may not work for sparse memory
> > as memory regions can be very far apart resulting incorrect removal of some
> > usable memory.
>
> If I understand correctly, the memory with physical addresses larger
> than (-PAGE_OFFSET) cannot be used. Since it was aready
> memblock_add()'ed during device tree parsing, you need to remove it from
> memblock.
>
IIRC, the original intention was to fix MAXPHYSMEM_2GB option for RV64
for the medlow model.
That's why the patch removed any memory beyond -PAGE_OFFSET.
> For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
>
Thanks. I think we can just call memblock_enforce_memory_limit without
tracking the total memory size
and whether maximum memory described in DT is greater than -PAGE_OFFSET.
@Anup Patel Was there any other reason for this change originally?
> > Just use the start of the first memory block and the end of the last memory
> > block to compute the size of the total memory that can be used.
> >
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > ---
> > arch/riscv/mm/init.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 787c75f751a5..188281fc2816 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > {
> > struct memblock_region *reg;
> > phys_addr_t mem_size = 0;
> > - phys_addr_t total_mem = 0;
> > phys_addr_t mem_start, end = 0;
> > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > /* Find the memory region containing the kernel */
> > for_each_memblock(memory, reg) {
> > end = reg->base + reg->size;
> > - if (!total_mem)
> > + if (!mem_start)
> > mem_start = reg->base;
> > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > BUG_ON(reg->size == 0);
> > - total_mem = total_mem + reg->size;
> > }
> >
> > /*
> > * Remove memblock from the end of usable area to the
> > * end of region
> > */
> > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > if (mem_start + mem_size < end)
> > memblock_remove(mem_start + mem_size,
> > end - mem_start - mem_size);
> > --
> > 2.24.0
> >
>
> --
> Sincerely yours,
> Mike.
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
--
Regards,
Atish
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
@ 2020-09-13 23:47 ` Atish Patra
0 siblings, 0 replies; 12+ messages in thread
From: Atish Patra @ 2020-09-13 23:47 UTC (permalink / raw)
To: Mike Rapoport, Anup Patel, Anup Patel
Cc: Atish Patra, Albert Ou, linux-kernel@vger.kernel.org List,
Palmer Dabbelt, Zong Li, Paul Walmsley, linux-riscv
On Sat, Sep 12, 2020 at 3:45 AM Mike Rapoport <rppt@kernel.org> wrote:
>
> Hello Atish,
>
> On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > Currently, any usable memory area beyond page_offset is removed by adding the
> > memory sizes from each memblock. That may not work for sparse memory
> > as memory regions can be very far apart resulting incorrect removal of some
> > usable memory.
>
> If I understand correctly, the memory with physical addresses larger
> than (-PAGE_OFFSET) cannot be used. Since it was aready
> memblock_add()'ed during device tree parsing, you need to remove it from
> memblock.
>
IIRC, the original intention was to fix MAXPHYSMEM_2GB option for RV64
for the medlow model.
That's why the patch removed any memory beyond -PAGE_OFFSET.
> For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
>
Thanks. I think we can just call memblock_enforce_memory_limit without
tracking the total memory size
and whether maximum memory described in DT is greater than -PAGE_OFFSET.
@Anup Patel Was there any other reason for this change originally?
> > Just use the start of the first memory block and the end of the last memory
> > block to compute the size of the total memory that can be used.
> >
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > ---
> > arch/riscv/mm/init.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 787c75f751a5..188281fc2816 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > {
> > struct memblock_region *reg;
> > phys_addr_t mem_size = 0;
> > - phys_addr_t total_mem = 0;
> > phys_addr_t mem_start, end = 0;
> > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > /* Find the memory region containing the kernel */
> > for_each_memblock(memory, reg) {
> > end = reg->base + reg->size;
> > - if (!total_mem)
> > + if (!mem_start)
> > mem_start = reg->base;
> > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > BUG_ON(reg->size == 0);
> > - total_mem = total_mem + reg->size;
> > }
> >
> > /*
> > * Remove memblock from the end of usable area to the
> > * end of region
> > */
> > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > if (mem_start + mem_size < end)
> > memblock_remove(mem_start + mem_size,
> > end - mem_start - mem_size);
> > --
> > 2.24.0
> >
>
> --
> Sincerely yours,
> Mike.
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
--
Regards,
Atish
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
2020-09-13 23:47 ` Atish Patra
@ 2020-09-14 11:52 ` Anup Patel
-1 siblings, 0 replies; 12+ messages in thread
From: Anup Patel @ 2020-09-14 11:52 UTC (permalink / raw)
To: Atish Patra
Cc: Albert Ou, Anup Patel, linux-kernel@vger.kernel.org List,
Atish Patra, Palmer Dabbelt, Zong Li, Paul Walmsley, linux-riscv,
Mike Rapoport
On Mon, Sep 14, 2020 at 5:18 AM Atish Patra <atishp@atishpatra.org> wrote:
>
> On Sat, Sep 12, 2020 at 3:45 AM Mike Rapoport <rppt@kernel.org> wrote:
> >
> > Hello Atish,
> >
> > On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > > Currently, any usable memory area beyond page_offset is removed by adding the
> > > memory sizes from each memblock. That may not work for sparse memory
> > > as memory regions can be very far apart resulting incorrect removal of some
> > > usable memory.
> >
> > If I understand correctly, the memory with physical addresses larger
> > than (-PAGE_OFFSET) cannot be used. Since it was aready
> > memblock_add()'ed during device tree parsing, you need to remove it from
> > memblock.
> >
>
> IIRC, the original intention was to fix MAXPHYSMEM_2GB option for RV64
> for the medlow model.
> That's why the patch removed any memory beyond -PAGE_OFFSET.
>
> > For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
> >
> Thanks. I think we can just call memblock_enforce_memory_limit without
> tracking the total memory size
> and whether maximum memory described in DT is greater than -PAGE_OFFSET.
>
> @Anup Patel Was there any other reason for this change originally?
No other reason. We just wanted to ensure that amount of memory addressable
by kernel (i.e. -PAGE_OFFSET) is also considered when removing memblock.
Regards,
Anup
>
> > > Just use the start of the first memory block and the end of the last memory
> > > block to compute the size of the total memory that can be used.
> > >
> > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > ---
> > > arch/riscv/mm/init.c | 6 ++----
> > > 1 file changed, 2 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > > index 787c75f751a5..188281fc2816 100644
> > > --- a/arch/riscv/mm/init.c
> > > +++ b/arch/riscv/mm/init.c
> > > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > > {
> > > struct memblock_region *reg;
> > > phys_addr_t mem_size = 0;
> > > - phys_addr_t total_mem = 0;
> > > phys_addr_t mem_start, end = 0;
> > > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > > /* Find the memory region containing the kernel */
> > > for_each_memblock(memory, reg) {
> > > end = reg->base + reg->size;
> > > - if (!total_mem)
> > > + if (!mem_start)
> > > mem_start = reg->base;
> > > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > > BUG_ON(reg->size == 0);
> > > - total_mem = total_mem + reg->size;
> > > }
> > >
> > > /*
> > > * Remove memblock from the end of usable area to the
> > > * end of region
> > > */
> > > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > > if (mem_start + mem_size < end)
> > > memblock_remove(mem_start + mem_size,
> > > end - mem_start - mem_size);
> > > --
> > > 2.24.0
> > >
> >
> > --
> > Sincerely yours,
> > Mike.
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>
>
>
> --
> Regards,
> Atish
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
@ 2020-09-14 11:52 ` Anup Patel
0 siblings, 0 replies; 12+ messages in thread
From: Anup Patel @ 2020-09-14 11:52 UTC (permalink / raw)
To: Atish Patra
Cc: Mike Rapoport, Anup Patel, Atish Patra, Albert Ou,
linux-kernel@vger.kernel.org List, Palmer Dabbelt, Zong Li,
Paul Walmsley, linux-riscv
On Mon, Sep 14, 2020 at 5:18 AM Atish Patra <atishp@atishpatra.org> wrote:
>
> On Sat, Sep 12, 2020 at 3:45 AM Mike Rapoport <rppt@kernel.org> wrote:
> >
> > Hello Atish,
> >
> > On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > > Currently, any usable memory area beyond page_offset is removed by adding the
> > > memory sizes from each memblock. That may not work for sparse memory
> > > as memory regions can be very far apart resulting incorrect removal of some
> > > usable memory.
> >
> > If I understand correctly, the memory with physical addresses larger
> > than (-PAGE_OFFSET) cannot be used. Since it was aready
> > memblock_add()'ed during device tree parsing, you need to remove it from
> > memblock.
> >
>
> IIRC, the original intention was to fix MAXPHYSMEM_2GB option for RV64
> for the medlow model.
> That's why the patch removed any memory beyond -PAGE_OFFSET.
>
> > For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
> >
> Thanks. I think we can just call memblock_enforce_memory_limit without
> tracking the total memory size
> and whether maximum memory described in DT is greater than -PAGE_OFFSET.
>
> @Anup Patel Was there any other reason for this change originally?
No other reason. We just wanted to ensure that amount of memory addressable
by kernel (i.e. -PAGE_OFFSET) is also considered when removing memblock.
Regards,
Anup
>
> > > Just use the start of the first memory block and the end of the last memory
> > > block to compute the size of the total memory that can be used.
> > >
> > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > ---
> > > arch/riscv/mm/init.c | 6 ++----
> > > 1 file changed, 2 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > > index 787c75f751a5..188281fc2816 100644
> > > --- a/arch/riscv/mm/init.c
> > > +++ b/arch/riscv/mm/init.c
> > > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > > {
> > > struct memblock_region *reg;
> > > phys_addr_t mem_size = 0;
> > > - phys_addr_t total_mem = 0;
> > > phys_addr_t mem_start, end = 0;
> > > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > > /* Find the memory region containing the kernel */
> > > for_each_memblock(memory, reg) {
> > > end = reg->base + reg->size;
> > > - if (!total_mem)
> > > + if (!mem_start)
> > > mem_start = reg->base;
> > > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > > BUG_ON(reg->size == 0);
> > > - total_mem = total_mem + reg->size;
> > > }
> > >
> > > /*
> > > * Remove memblock from the end of usable area to the
> > > * end of region
> > > */
> > > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > > if (mem_start + mem_size < end)
> > > memblock_remove(mem_start + mem_size,
> > > end - mem_start - mem_size);
> > > --
> > > 2.24.0
> > >
> >
> > --
> > Sincerely yours,
> > Mike.
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>
>
>
> --
> Regards,
> Atish
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
2020-09-14 11:52 ` Anup Patel
@ 2020-09-14 17:53 ` Atish Patra
-1 siblings, 0 replies; 12+ messages in thread
From: Atish Patra @ 2020-09-14 17:53 UTC (permalink / raw)
To: Anup Patel
Cc: Albert Ou, Anup Patel, linux-kernel@vger.kernel.org List,
Atish Patra, Palmer Dabbelt, Zong Li, Paul Walmsley, linux-riscv,
Mike Rapoport
On Mon, Sep 14, 2020 at 4:52 AM Anup Patel <anup@brainfault.org> wrote:
>
> On Mon, Sep 14, 2020 at 5:18 AM Atish Patra <atishp@atishpatra.org> wrote:
> >
> > On Sat, Sep 12, 2020 at 3:45 AM Mike Rapoport <rppt@kernel.org> wrote:
> > >
> > > Hello Atish,
> > >
> > > On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > > > Currently, any usable memory area beyond page_offset is removed by adding the
> > > > memory sizes from each memblock. That may not work for sparse memory
> > > > as memory regions can be very far apart resulting incorrect removal of some
> > > > usable memory.
> > >
> > > If I understand correctly, the memory with physical addresses larger
> > > than (-PAGE_OFFSET) cannot be used. Since it was aready
> > > memblock_add()'ed during device tree parsing, you need to remove it from
> > > memblock.
> > >
> >
> > IIRC, the original intention was to fix MAXPHYSMEM_2GB option for RV64
> > for the medlow model.
> > That's why the patch removed any memory beyond -PAGE_OFFSET.
> >
> > > For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
> > >
> > Thanks. I think we can just call memblock_enforce_memory_limit without
> > tracking the total memory size
> > and whether maximum memory described in DT is greater than -PAGE_OFFSET.
> >
> > @Anup Patel Was there any other reason for this change originally?
>
> No other reason. We just wanted to ensure that amount of memory addressable
> by kernel (i.e. -PAGE_OFFSET) is also considered when removing memblock.
>
It looks like we have an agreement here then. I will update the patch
to directly call
memblock_enforce_memory_limit as suggested by Mike.
> Regards,
> Anup
>
> >
> > > > Just use the start of the first memory block and the end of the last memory
> > > > block to compute the size of the total memory that can be used.
> > > >
> > > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > > ---
> > > > arch/riscv/mm/init.c | 6 ++----
> > > > 1 file changed, 2 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > > > index 787c75f751a5..188281fc2816 100644
> > > > --- a/arch/riscv/mm/init.c
> > > > +++ b/arch/riscv/mm/init.c
> > > > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > > > {
> > > > struct memblock_region *reg;
> > > > phys_addr_t mem_size = 0;
> > > > - phys_addr_t total_mem = 0;
> > > > phys_addr_t mem_start, end = 0;
> > > > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > > > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > > > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > > > /* Find the memory region containing the kernel */
> > > > for_each_memblock(memory, reg) {
> > > > end = reg->base + reg->size;
> > > > - if (!total_mem)
> > > > + if (!mem_start)
> > > > mem_start = reg->base;
> > > > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > > > BUG_ON(reg->size == 0);
> > > > - total_mem = total_mem + reg->size;
> > > > }
> > > >
> > > > /*
> > > > * Remove memblock from the end of usable area to the
> > > > * end of region
> > > > */
> > > > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > > > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > > > if (mem_start + mem_size < end)
> > > > memblock_remove(mem_start + mem_size,
> > > > end - mem_start - mem_size);
> > > > --
> > > > 2.24.0
> > > >
> > >
> > > --
> > > Sincerely yours,
> > > Mike.
> > >
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
> >
> >
> > --
> > Regards,
> > Atish
--
Regards,
Atish
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
@ 2020-09-14 17:53 ` Atish Patra
0 siblings, 0 replies; 12+ messages in thread
From: Atish Patra @ 2020-09-14 17:53 UTC (permalink / raw)
To: Anup Patel
Cc: Mike Rapoport, Anup Patel, Atish Patra, Albert Ou,
linux-kernel@vger.kernel.org List, Palmer Dabbelt, Zong Li,
Paul Walmsley, linux-riscv
On Mon, Sep 14, 2020 at 4:52 AM Anup Patel <anup@brainfault.org> wrote:
>
> On Mon, Sep 14, 2020 at 5:18 AM Atish Patra <atishp@atishpatra.org> wrote:
> >
> > On Sat, Sep 12, 2020 at 3:45 AM Mike Rapoport <rppt@kernel.org> wrote:
> > >
> > > Hello Atish,
> > >
> > > On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > > > Currently, any usable memory area beyond page_offset is removed by adding the
> > > > memory sizes from each memblock. That may not work for sparse memory
> > > > as memory regions can be very far apart resulting incorrect removal of some
> > > > usable memory.
> > >
> > > If I understand correctly, the memory with physical addresses larger
> > > than (-PAGE_OFFSET) cannot be used. Since it was aready
> > > memblock_add()'ed during device tree parsing, you need to remove it from
> > > memblock.
> > >
> >
> > IIRC, the original intention was to fix MAXPHYSMEM_2GB option for RV64
> > for the medlow model.
> > That's why the patch removed any memory beyond -PAGE_OFFSET.
> >
> > > For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
> > >
> > Thanks. I think we can just call memblock_enforce_memory_limit without
> > tracking the total memory size
> > and whether maximum memory described in DT is greater than -PAGE_OFFSET.
> >
> > @Anup Patel Was there any other reason for this change originally?
>
> No other reason. We just wanted to ensure that amount of memory addressable
> by kernel (i.e. -PAGE_OFFSET) is also considered when removing memblock.
>
It looks like we have an agreement here then. I will update the patch
to directly call
memblock_enforce_memory_limit as suggested by Mike.
> Regards,
> Anup
>
> >
> > > > Just use the start of the first memory block and the end of the last memory
> > > > block to compute the size of the total memory that can be used.
> > > >
> > > > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > > > ---
> > > > arch/riscv/mm/init.c | 6 ++----
> > > > 1 file changed, 2 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > > > index 787c75f751a5..188281fc2816 100644
> > > > --- a/arch/riscv/mm/init.c
> > > > +++ b/arch/riscv/mm/init.c
> > > > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > > > {
> > > > struct memblock_region *reg;
> > > > phys_addr_t mem_size = 0;
> > > > - phys_addr_t total_mem = 0;
> > > > phys_addr_t mem_start, end = 0;
> > > > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > > > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > > > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > > > /* Find the memory region containing the kernel */
> > > > for_each_memblock(memory, reg) {
> > > > end = reg->base + reg->size;
> > > > - if (!total_mem)
> > > > + if (!mem_start)
> > > > mem_start = reg->base;
> > > > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > > > BUG_ON(reg->size == 0);
> > > > - total_mem = total_mem + reg->size;
> > > > }
> > > >
> > > > /*
> > > > * Remove memblock from the end of usable area to the
> > > > * end of region
> > > > */
> > > > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > > > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > > > if (mem_start + mem_size < end)
> > > > memblock_remove(mem_start + mem_size,
> > > > end - mem_start - mem_size);
> > > > --
> > > > 2.24.0
> > > >
> > >
> > > --
> > > Sincerely yours,
> > > Mike.
> > >
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
> >
> >
> > --
> > Regards,
> > Atish
--
Regards,
Atish
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
2020-09-12 10:45 ` Mike Rapoport
@ 2020-09-14 11:49 ` Anup Patel
-1 siblings, 0 replies; 12+ messages in thread
From: Anup Patel @ 2020-09-14 11:49 UTC (permalink / raw)
To: Mike Rapoport
Cc: Albert Ou, Anup Patel, linux-kernel@vger.kernel.org List,
Atish Patra, Palmer Dabbelt, Zong Li, Paul Walmsley, linux-riscv
On Sat, Sep 12, 2020 at 4:15 PM Mike Rapoport <rppt@kernel.org> wrote:
>
> Hello Atish,
>
> On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > Currently, any usable memory area beyond page_offset is removed by adding the
> > memory sizes from each memblock. That may not work for sparse memory
> > as memory regions can be very far apart resulting incorrect removal of some
> > usable memory.
>
> If I understand correctly, the memory with physical addresses larger
> than (-PAGE_OFFSET) cannot be used. Since it was aready
> memblock_add()'ed during device tree parsing, you need to remove it from
> memblock.
-PAGE_OFFSET represents the size of memory addressable by the kernel and
not the last physical address.
mem_start + (-PAGE_OFFSET) will be the last physical address usable by kernel.
>
> For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
I think we should use memblock_enforce_memory_limit(mem_start - PAGE_OFFSET).
Regards,
Anup
>
> > Just use the start of the first memory block and the end of the last memory
> > block to compute the size of the total memory that can be used.
> >
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > ---
> > arch/riscv/mm/init.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 787c75f751a5..188281fc2816 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > {
> > struct memblock_region *reg;
> > phys_addr_t mem_size = 0;
> > - phys_addr_t total_mem = 0;
> > phys_addr_t mem_start, end = 0;
> > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > /* Find the memory region containing the kernel */
> > for_each_memblock(memory, reg) {
> > end = reg->base + reg->size;
> > - if (!total_mem)
> > + if (!mem_start)
> > mem_start = reg->base;
> > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > BUG_ON(reg->size == 0);
> > - total_mem = total_mem + reg->size;
> > }
> >
> > /*
> > * Remove memblock from the end of usable area to the
> > * end of region
> > */
> > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > if (mem_start + mem_size < end)
> > memblock_remove(mem_start + mem_size,
> > end - mem_start - mem_size);
> > --
> > 2.24.0
> >
>
> --
> Sincerely yours,
> Mike.
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH] RISC-V: Consider sparse memory while removing unusable memory
@ 2020-09-14 11:49 ` Anup Patel
0 siblings, 0 replies; 12+ messages in thread
From: Anup Patel @ 2020-09-14 11:49 UTC (permalink / raw)
To: Mike Rapoport
Cc: Atish Patra, linux-kernel@vger.kernel.org List, Albert Ou,
Anup Patel, linux-riscv, Palmer Dabbelt, Paul Walmsley, Zong Li
On Sat, Sep 12, 2020 at 4:15 PM Mike Rapoport <rppt@kernel.org> wrote:
>
> Hello Atish,
>
> On Fri, Sep 11, 2020 at 05:23:41PM -0700, Atish Patra wrote:
> > Currently, any usable memory area beyond page_offset is removed by adding the
> > memory sizes from each memblock. That may not work for sparse memory
> > as memory regions can be very far apart resulting incorrect removal of some
> > usable memory.
>
> If I understand correctly, the memory with physical addresses larger
> than (-PAGE_OFFSET) cannot be used. Since it was aready
> memblock_add()'ed during device tree parsing, you need to remove it from
> memblock.
-PAGE_OFFSET represents the size of memory addressable by the kernel and
not the last physical address.
mem_start + (-PAGE_OFFSET) will be the last physical address usable by kernel.
>
> For that you can use memblock_enforce_memory_limit(-PAGE_OFFSET).
I think we should use memblock_enforce_memory_limit(mem_start - PAGE_OFFSET).
Regards,
Anup
>
> > Just use the start of the first memory block and the end of the last memory
> > block to compute the size of the total memory that can be used.
> >
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
> > ---
> > arch/riscv/mm/init.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 787c75f751a5..188281fc2816 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -147,7 +147,6 @@ void __init setup_bootmem(void)
> > {
> > struct memblock_region *reg;
> > phys_addr_t mem_size = 0;
> > - phys_addr_t total_mem = 0;
> > phys_addr_t mem_start, end = 0;
> > phys_addr_t vmlinux_end = __pa_symbol(&_end);
> > phys_addr_t vmlinux_start = __pa_symbol(&_start);
> > @@ -155,18 +154,17 @@ void __init setup_bootmem(void)
> > /* Find the memory region containing the kernel */
> > for_each_memblock(memory, reg) {
> > end = reg->base + reg->size;
> > - if (!total_mem)
> > + if (!mem_start)
> > mem_start = reg->base;
> > if (reg->base <= vmlinux_start && vmlinux_end <= end)
> > BUG_ON(reg->size == 0);
> > - total_mem = total_mem + reg->size;
> > }
> >
> > /*
> > * Remove memblock from the end of usable area to the
> > * end of region
> > */
> > - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> > + mem_size = min(end - mem_start, (phys_addr_t)-PAGE_OFFSET);
> > if (mem_start + mem_size < end)
> > memblock_remove(mem_start + mem_size,
> > end - mem_start - mem_size);
> > --
> > 2.24.0
> >
>
> --
> Sincerely yours,
> Mike.
^ permalink raw reply [flat|nested] 12+ messages in thread