Messages in this thread | | | Date | Tue, 25 Aug 2015 16:08:33 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] mm: Check if section present during memory block (un)registering |
| |
On Tue, 25 Aug 2015 15:41:16 -0700 Yinghai Lu <yinghai@kernel.org> wrote:
> Tony found on his setup, if memory block size 512M will cause crash > during booting. > > BUG: unable to handle kernel paging request at ffffea0074000020 > IP: [<ffffffff81670527>] get_nid_for_pfn+0x17/0x40 > PGD 128ffcb067 PUD 128ffc9067 PMD 0 > Oops: 0000 [#1] SMP > Modules linked in: > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.2.0-rc8 #1 > ... > Call Trace: > [<ffffffff81453b56>] ? register_mem_sect_under_node+0x66/0xe0 > [<ffffffff81453eeb>] register_one_node+0x17b/0x240 > [<ffffffff81b1f1ed>] ? pci_iommu_alloc+0x6e/0x6e > [<ffffffff81b1f229>] topology_init+0x3c/0x95 > [<ffffffff8100213d>] do_one_initcall+0xcd/0x1f0 > > The system has non continuous RAM address: > BIOS-e820: [mem 0x0000001300000000-0x0000001cffffffff] usable > BIOS-e820: [mem 0x0000001d70000000-0x0000001ec7ffefff] usable > BIOS-e820: [mem 0x0000001f00000000-0x0000002bffffffff] usable > BIOS-e820: [mem 0x0000002c18000000-0x0000002d6fffefff] usable > BIOS-e820: [mem 0x0000002e00000000-0x00000039ffffffff] usable > > So there are start sections in memory block not present. > For example: > memory block : [0x2c18000000, 0x2c20000000) 512M > first three sections are not present. > > Current register_mem_sect_under_node() assume first section is present, > but memory block section number range [start_section_nr, end_section_nr] > would include not present section. > > For arch that support vmemmap, we don't setup memmap for struct page area > within not present sections area. > > So skip the pfn range that belong to not present section. > > Als fixes unregister_mem_sect_under_nodes().
It appears this should be backported into -stable kernels, yes? Do you know which kernel versions need the fix?
> --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -390,8 +390,14 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, int nid) > 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; > + int page_nid, scn_nr; > > + scn_nr = pfn_to_section_nr(pfn); > + if (!present_section_nr(scn_nr)) { > + pfn = round_down(pfn + PAGES_PER_SECTION, > + PAGES_PER_SECTION) - 1; > + continue; > + }
Can we please add a comment here telling readers why this is being done? What scenario is being detected and how it comes about.
> page_nid = get_nid_for_pfn(pfn); > if (page_nid < 0) > continue;
| |