Re: [PATCH 1/2] drivers/base/node.c: split loop in register_mem_sect_under_node

Re: [PATCH 1/2] drivers/base/node.c: split loop in register_mem_sect_under_node

[Dave Young]

Ccing linux-mm

On 08/27/15 at 04:43pm, Jan Stancek wrote:
> Split single loop going over all pfn in mem_blk into 2 loops,
> where outer loop goes over all sections and inner loop goes over
> pfn from that section.
> 
> This is preparatory patch for next patch:
>   "skip non-present sections in register_mem_sect_under_node"
> 
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/base/node.c | 41 ++++++++++++++++++++++++-----------------
>  1 file changed, 24 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 31df474d72f4..4c7423a4b5f4 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -379,33 +379,40 @@ static int __init_refok get_nid_for_pfn(unsigned long pfn)
>  int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
>  {
>  	int ret;
> -	unsigned long pfn, sect_start_pfn, sect_end_pfn;
> +	unsigned long pfn, sect_start_pfn, sect_end_pfn, sect_no;
>  
>  	if (!mem_blk)
>  		return -EFAULT;
>  	if (!node_online(nid))
>  		return 0;
>  
> -	sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
> -	sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
> -	sect_end_pfn += PAGES_PER_SECTION - 1;
> -	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
> -		int page_nid;
> +	for (sect_no = mem_blk->start_section_nr;
> +		sect_no <= mem_blk->end_section_nr;
> +		sect_no++) {
>  
> -		page_nid = get_nid_for_pfn(pfn);
> -		if (page_nid < 0)
> -			continue;
> -		if (page_nid != nid)
> -			continue;
> -		ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
> -					&mem_blk->dev.kobj,
> -					kobject_name(&mem_blk->dev.kobj));
> -		if (ret)
> -			return ret;
> +		sect_start_pfn = section_nr_to_pfn(sect_no);
> +		sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
> +
> +		for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
> +			int page_nid;
>  
> -		return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
> +			page_nid = get_nid_for_pfn(pfn);
> +			if (page_nid < 0)
> +				continue;
> +			if (page_nid != nid)
> +				continue;
> +
> +			ret = sysfs_create_link_nowarn(
> +				&node_devices[nid]->dev.kobj,
> +				&mem_blk->dev.kobj,
> +				kobject_name(&mem_blk->dev.kobj));
> +			if (ret)
> +				return ret;
> +
> +			return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
>  				&node_devices[nid]->dev.kobj,
>  				kobject_name(&node_devices[nid]->dev.kobj));
> +		}
>  	}
>  	/* mem section does not span the specified node */
>  	return 0;
> -- 
> 1.8.3.1
> 
> --
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Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node

[Dave Young]

On 08/27/15 at 04:43pm, Jan Stancek wrote:
> Skip non-present sections in mem_blk to avoid crashing during boot
> at register_mem_sect_under_node()->get_nid_for_pfn():
> 
>   Unable to handle kernel paging request for data at address 0xf000000000080020
>   Faulting instruction address: 0xc00000000866b480
>   Oops: Kernel access of bad area, sig: 11 [#1]
>   SMP NR_CPUS=2048 NUMA pSeries
>   Modules linked in:
>   CPU: 14 PID: 1 Comm: swapper/14 Not tainted 4.2.0-rc8+ #6
>   task: c00000001e480000 ti: c00000001e500000 task.ti: c00000001e500000
>   NIP: c00000000866b480 LR: c00000000851aecc CTR: 0000000000000400
>   ...
>   NIP [c00000000866b480] get_nid_for_pfn+0x10/0x30
>   LR [c00000000851aecc] register_mem_sect_under_node+0x9c/0x190
>   Call Trace:
>   [c00000001e503b10] [c0000000084f89a4] put_device+0x24/0x40 (unreliable)
>   [c00000001e503b60] [c00000000851b3d4] register_one_node+0x2b4/0x390
>   [c00000001e503bc0] [c000000008ae7a50] topology_init+0x4c/0x1e8
>   [c00000001e503c30] [c00000000800b3bc] do_one_initcall+0x10c/0x260
>   [c00000001e503d00] [c000000008ae41b4] kernel_init_freeable+0x27c/0x364
>   [c00000001e503dc0] [c00000000800bc14] kernel_init+0x24/0x130
>   [c00000001e503e30] [c000000008009530] ret_from_kernel_thread+0x5c/0xac
>   Instruction dump:
>   4e800020 60000000 60000000 60420000 3b80ffed 4bffffc8 00000000 00000000
>   3920ffff 78633664 792900c4 7d434a14 <e94a0020> 2faa0000 41de0010 7c63482a
>   ---[ end trace e9ab4a173e0cee14 ]---
> 
> This has been observed during kdump kernel boot on ppc64le KVM guest
> (page size: 65536, sections_per_block: 16, PAGES_PER_SECTION: 256)
> where kdump adds "rtas" to list of usable regions:
>   # hexdump -C /sys/firmware/devicetree/base/rtas/linux,rtas-base
>   00000000  2f ff 00 00                                       |/...|
> 
> [    0.000000] Early memory node ranges
> [    0.000000]   node   0: [mem 0x0000000000000000-0x000000001fffffff]
> [    0.000000]   node   0: [mem 0x000000002fff0000-0x000000002fffffff]
> 
> Crash happens when register_mem_sect_under_node goes over mem_blk that
> spans sections 32-47, 32-46 are not present, 47 is present:
>   32 * 256 * 65536 == 0x20000000
>   47 * 256 * 65536 == 0x2f000000
> It tries to access page for first pfn of this mem_blk (8192 == 32 * 256)
> and crashes.
> 
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/base/node.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 4c7423a4b5f4..e638cfde7486 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -390,6 +390,9 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
>  		sect_no <= mem_blk->end_section_nr;
>  		sect_no++) {
>  
> +		if (!present_section_nr(sect_no))
> +			continue;
> +
>  		sect_start_pfn = section_nr_to_pfn(sect_no);
>  		sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
>  
> -- 
> 1.8.3.1
> 
> --
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Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node

[Jan Stancek]

Greg,

any thoughts about the patch?

Regards,
Jan

----- Original Message -----
> From: "Dave Young" <dyoung@redhat.com>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
> Sent: Tuesday, 1 September, 2015 9:15:53 AM
> Subject: Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node
> 
> On 08/27/15 at 04:43pm, Jan Stancek wrote:
> > Skip non-present sections in mem_blk to avoid crashing during boot
> > at register_mem_sect_under_node()->get_nid_for_pfn():
> > 
> >   Unable to handle kernel paging request for data at address
> >   0xf000000000080020
> >   Faulting instruction address: 0xc00000000866b480
> >   Oops: Kernel access of bad area, sig: 11 [#1]
> >   SMP NR_CPUS=2048 NUMA pSeries
> >   Modules linked in:
> >   CPU: 14 PID: 1 Comm: swapper/14 Not tainted 4.2.0-rc8+ #6
> >   task: c00000001e480000 ti: c00000001e500000 task.ti: c00000001e500000
> >   NIP: c00000000866b480 LR: c00000000851aecc CTR: 0000000000000400
> >   ...
> >   NIP [c00000000866b480] get_nid_for_pfn+0x10/0x30
> >   LR [c00000000851aecc] register_mem_sect_under_node+0x9c/0x190
> >   Call Trace:
> >   [c00000001e503b10] [c0000000084f89a4] put_device+0x24/0x40 (unreliable)
> >   [c00000001e503b60] [c00000000851b3d4] register_one_node+0x2b4/0x390
> >   [c00000001e503bc0] [c000000008ae7a50] topology_init+0x4c/0x1e8
> >   [c00000001e503c30] [c00000000800b3bc] do_one_initcall+0x10c/0x260
> >   [c00000001e503d00] [c000000008ae41b4] kernel_init_freeable+0x27c/0x364
> >   [c00000001e503dc0] [c00000000800bc14] kernel_init+0x24/0x130
> >   [c00000001e503e30] [c000000008009530] ret_from_kernel_thread+0x5c/0xac
> >   Instruction dump:
> >   4e800020 60000000 60000000 60420000 3b80ffed 4bffffc8 00000000 00000000
> >   3920ffff 78633664 792900c4 7d434a14 <e94a0020> 2faa0000 41de0010 7c63482a
> >   ---[ end trace e9ab4a173e0cee14 ]---
> > 
> > This has been observed during kdump kernel boot on ppc64le KVM guest
> > (page size: 65536, sections_per_block: 16, PAGES_PER_SECTION: 256)
> > where kdump adds "rtas" to list of usable regions:
> >   # hexdump -C /sys/firmware/devicetree/base/rtas/linux,rtas-base
> >   00000000  2f ff 00 00                                       |/...|
> > 
> > [    0.000000] Early memory node ranges
> > [    0.000000]   node   0: [mem 0x0000000000000000-0x000000001fffffff]
> > [    0.000000]   node   0: [mem 0x000000002fff0000-0x000000002fffffff]
> > 
> > Crash happens when register_mem_sect_under_node goes over mem_blk that
> > spans sections 32-47, 32-46 are not present, 47 is present:
> >   32 * 256 * 65536 == 0x20000000
> >   47 * 256 * 65536 == 0x2f000000
> > It tries to access page for first pfn of this mem_blk (8192 == 32 * 256)
> > and crashes.
> > 
> > Signed-off-by: Jan Stancek <jstancek@redhat.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > ---
> >  drivers/base/node.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/base/node.c b/drivers/base/node.c
> > index 4c7423a4b5f4..e638cfde7486 100644
> > --- a/drivers/base/node.c
> > +++ b/drivers/base/node.c
> > @@ -390,6 +390,9 @@ int register_mem_sect_under_node(struct memory_block
> > *mem_blk, int nid)
> >  		sect_no <= mem_blk->end_section_nr;
> >  		sect_no++) {
> >  
> > +		if (!present_section_nr(sect_no))
> > +			continue;
> > +
> >  		sect_start_pfn = section_nr_to_pfn(sect_no);
> >  		sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
> >  
> > --
> > 1.8.3.1
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> 

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Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node

[Jan Stancek]

----- Original Message -----
> From: "Jan Stancek" <jstancek@redhat.com>
> To: gregkh@linuxfoundation.org
> Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Dave Young" <dyoung@redhat.com>
> Sent: Wednesday, 9 September, 2015 1:11:23 PM
> Subject: Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node
> 
> Greg,
> 
> any thoughts about the patch?

ping

> 
> Regards,
> Jan
> 
> ----- Original Message -----
> > From: "Dave Young" <dyoung@redhat.com>
> > To: "Jan Stancek" <jstancek@redhat.com>
> > Cc: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
> > linux-mm@kvack.org
> > Sent: Tuesday, 1 September, 2015 9:15:53 AM
> > Subject: Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in
> > register_mem_sect_under_node
> > 
> > On 08/27/15 at 04:43pm, Jan Stancek wrote:
> > > Skip non-present sections in mem_blk to avoid crashing during boot
> > > at register_mem_sect_under_node()->get_nid_for_pfn():
> > > 
> > >   Unable to handle kernel paging request for data at address
> > >   0xf000000000080020
> > >   Faulting instruction address: 0xc00000000866b480
> > >   Oops: Kernel access of bad area, sig: 11 [#1]
> > >   SMP NR_CPUS=2048 NUMA pSeries
> > >   Modules linked in:
> > >   CPU: 14 PID: 1 Comm: swapper/14 Not tainted 4.2.0-rc8+ #6
> > >   task: c00000001e480000 ti: c00000001e500000 task.ti: c00000001e500000
> > >   NIP: c00000000866b480 LR: c00000000851aecc CTR: 0000000000000400
> > >   ...
> > >   NIP [c00000000866b480] get_nid_for_pfn+0x10/0x30
> > >   LR [c00000000851aecc] register_mem_sect_under_node+0x9c/0x190
> > >   Call Trace:
> > >   [c00000001e503b10] [c0000000084f89a4] put_device+0x24/0x40 (unreliable)
> > >   [c00000001e503b60] [c00000000851b3d4] register_one_node+0x2b4/0x390
> > >   [c00000001e503bc0] [c000000008ae7a50] topology_init+0x4c/0x1e8
> > >   [c00000001e503c30] [c00000000800b3bc] do_one_initcall+0x10c/0x260
> > >   [c00000001e503d00] [c000000008ae41b4] kernel_init_freeable+0x27c/0x364
> > >   [c00000001e503dc0] [c00000000800bc14] kernel_init+0x24/0x130
> > >   [c00000001e503e30] [c000000008009530] ret_from_kernel_thread+0x5c/0xac
> > >   Instruction dump:
> > >   4e800020 60000000 60000000 60420000 3b80ffed 4bffffc8 00000000 00000000
> > >   3920ffff 78633664 792900c4 7d434a14 <e94a0020> 2faa0000 41de0010
> > >   7c63482a
> > >   ---[ end trace e9ab4a173e0cee14 ]---
> > > 
> > > This has been observed during kdump kernel boot on ppc64le KVM guest
> > > (page size: 65536, sections_per_block: 16, PAGES_PER_SECTION: 256)
> > > where kdump adds "rtas" to list of usable regions:
> > >   # hexdump -C /sys/firmware/devicetree/base/rtas/linux,rtas-base
> > >   00000000  2f ff 00 00                                       |/...|
> > > 
> > > [    0.000000] Early memory node ranges
> > > [    0.000000]   node   0: [mem 0x0000000000000000-0x000000001fffffff]
> > > [    0.000000]   node   0: [mem 0x000000002fff0000-0x000000002fffffff]
> > > 
> > > Crash happens when register_mem_sect_under_node goes over mem_blk that
> > > spans sections 32-47, 32-46 are not present, 47 is present:
> > >   32 * 256 * 65536 == 0x20000000
> > >   47 * 256 * 65536 == 0x2f000000
> > > It tries to access page for first pfn of this mem_blk (8192 == 32 * 256)
> > > and crashes.
> > > 
> > > Signed-off-by: Jan Stancek <jstancek@redhat.com>
> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > ---
> > >  drivers/base/node.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/drivers/base/node.c b/drivers/base/node.c
> > > index 4c7423a4b5f4..e638cfde7486 100644
> > > --- a/drivers/base/node.c
> > > +++ b/drivers/base/node.c
> > > @@ -390,6 +390,9 @@ int register_mem_sect_under_node(struct memory_block
> > > *mem_blk, int nid)
> > >  		sect_no <= mem_blk->end_section_nr;
> > >  		sect_no++) {
> > >  
> > > +		if (!present_section_nr(sect_no))
> > > +			continue;
> > > +
> > >  		sect_start_pfn = section_nr_to_pfn(sect_no);
> > >  		sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
> > >  
> > > --
> > > 1.8.3.1
> > > 
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-kernel"
> > > in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > > Please read the FAQ at  http://www.tux.org/lkml/
> > 
> 

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Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node

[Greg KH]

On Tue, Sep 22, 2015 at 04:27:01AM -0400, Jan Stancek wrote:
> 
> 
> 
> 
> ----- Original Message -----
> > From: "Jan Stancek" <jstancek@redhat.com>
> > To: gregkh@linuxfoundation.org
> > Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Dave Young" <dyoung@redhat.com>
> > Sent: Wednesday, 9 September, 2015 1:11:23 PM
> > Subject: Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node
> > 
> > Greg,
> > 
> > any thoughts about the patch?
> 
> ping

I need some -mm people to sign off on it, as this code is tricky and I
think has caused problems in the past, and I know nothing about it...

So please resend and get some acks from them and I'll be glad to take
it.

thanks,

greg k-h

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Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node

[Jan Stancek]

----- Original Message -----
> From: "Greg KH" <gregkh@linuxfoundation.org>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Dave Young" <dyoung@redhat.com>
> Sent: Sunday, 4 October, 2015 2:06:39 PM
> Subject: Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections in register_mem_sect_under_node
> 
> On Tue, Sep 22, 2015 at 04:27:01AM -0400, Jan Stancek wrote:
> > 
> > 
> > 
> > 
> > ----- Original Message -----
> > > From: "Jan Stancek" <jstancek@redhat.com>
> > > To: gregkh@linuxfoundation.org
> > > Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Dave Young"
> > > <dyoung@redhat.com>
> > > Sent: Wednesday, 9 September, 2015 1:11:23 PM
> > > Subject: Re: [PATCH 2/2] drivers/base/node.c: skip non-present sections
> > > in register_mem_sect_under_node
> > > 
> > > Greg,
> > > 
> > > any thoughts about the patch?
> > 
> > ping
> 
> I need some -mm people to sign off on it, as this code is tricky and I
> think has caused problems in the past, and I know nothing about it...

Thanks for response, get_maintainer.pl was giving me only your name.

> 
> So please resend and get some acks from them and I'll be glad to take
> it.

It looks like someone has already beat me to it:

commit 04697858d89e4bf2650364f8d6956e2554e8ef88
  mm: check if section present during memory block registering

Regards,
Jan

> 
> thanks,
> 
> greg k-h
> 

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