----- Original Message ----- > From: "Jan Stancek" <jstancek@xxxxxxxxxx> > To: gregkh@xxxxxxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, "Dave Young" <dyoung@xxxxxxxxxx> > 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@xxxxxxxxxx> > > To: "Jan Stancek" <jstancek@xxxxxxxxxx> > > Cc: gregkh@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, > > linux-mm@xxxxxxxxx > > 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@xxxxxxxxxx> > > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > --- > > > 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@xxxxxxxxxxxxxxx > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Please read the FAQ at http://www.tux.org/lkml/ > > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>