On Tue, Jul 12, 2016 at 04:26:02PM -0700, David Rientjes wrote: > On Fri, 8 Jul 2016, Mel Gorman wrote: > > > early_pfn_to_nid can return node 0 if a PFN is invalid on machines > > that has no node 0. A machine with only node 1 was observed to crash > > with the following message > > > > BUG: unable to handle kernel paging request at 000000000002a3c8 > > PGD 0 > > Modules linked in: > > Hardware name: Supermicro H8DSP-8/H8DSP-8, BIOS 080011 06/30/2006 > > task: ffffffff81c0d500 ti: ffffffff81c00000 task.ti: ffffffff81c00000 > > RIP: 0010:[<ffffffff816dbd63>] [<ffffffff816dbd63>] reserve_bootmem_region+0x6a/0xef > > RSP: 0000:ffffffff81c03eb0 EFLAGS: 00010086 > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > > RDX: ffffffff81c03ec0 RSI: ffffffff81d205c0 RDI: ffffffff8213ee60 > > R13: ffffea0000000000 R14: ffffea0000000020 R15: ffffea0000000020 > > FS: 0000000000000000(0000) GS:ffff8800fba00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 000000000002a3c8 CR3: 0000000001c06000 CR4: 00000000000006b0 > > Stack: > > ffffffff81c03f00 0000000000000400 ffff8800fbfc3200 ffffffff81e2a2c0 > > ffffffff81c03fb0 ffffffff81c03f20 ffffffff81dadf7d ffffea0002000040 > > ffffea0000000000 0000000000000000 000000000000ffff 0000000000000001 > > Call Trace: > > [<ffffffff81dadf7d>] free_all_bootmem+0x4b/0x12a > > [<ffffffff81d97122>] mem_init+0x70/0xa3 > > [<ffffffff81d78f21>] start_kernel+0x25b/0x49b > > > > The problem is that early_page_uninitialised uses the early_pfn_to_nid > > helper which returns node 0 for invalid PFNs. No caller of early_pfn_to_nid > > cares except early_page_uninitialised. This patch has early_pfn_to_nid > > always return a valid node. > > > > Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> > > Cc: <stable@xxxxxxxxxxxxxxx> # 4.2+ > > Acked-by: David Rientjes <rientjes@xxxxxxxxxx> > > This makes me wonder about meminit_pfn_in_nid(), however, since if > __early_pfn_to_nid() returns -1, which is the case in this bug, > meminit_pfn_in_nid() will return true for any passed node. I felt it was ok because it's checking for overlapping nodes primarily. If there is a hole, the pfn_valid check should fail for sparsemem. For flatmem, there is no concern with overlapping nodes. Technically the meminit_pfn_in_nid() call can return true for a hole but for sparsemem, that is checked for by pfn_valid and for flatmem, it doesn't matter. -- Mel Gorman SUSE Labs -- 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>