Hi, Some more information on the crash, inline.
On 02/17/2017 02:18 PM, Aneesh Kumar K.V wrote: > laurentiu.tu...@nxp.com writes: > >> From: Laurentiu Tudor <laurentiu.tu...@nxp.com> >> >> On 32-bit book-e machines, hugepd_ok() does not take >> into account null hugepd values, causing this crash at boot: >> >> Unable to handle kernel paging request for data at address 0x80000000 >> Faulting instruction address: 0xc00182a8 >> Oops: Kernel access of bad area, sig: 11 [#1] >> SMP NR_CPUS=24 >> CoreNet Generic >> Modules linked in: >> CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W >> 4.10.0-rc8-00016-g69b1f87 #11 >> task: e5050000 task.stack: e5058000 >> NIP: c00182a8 LR: c001829c CTR: 00007ffe >> REGS: e5059c50 TRAP: 0300 Tainted: G W >> (4.10.0-rc8-00016-g69b1f87) >> MSR: 00021002 <CE,ME> >> CR: 88428e82 XER: 00000000 >> DEAR: 80000000 ESR: 00000000 >> GPR00: c0107510 e5059d00 e5050000 80000000 bffffff1 e5059d0c e5059d08 >> 00002017 >> GPR08: 00000000 00000000 00000000 00000000 28428e82 00000000 c00027d0 >> 00000000 >> GPR16: 00000000 00000000 88a28e82 20000000 48422e82 00000000 88a28e84 >> dd004000 >> GPR24: e5059e38 00000000 00000000 bffffff1 dd004000 00000001 00029002 >> bffffff1 >> NIP [c00182a8] follow_huge_addr+0x38/0xf0 >> LR [c001829c] follow_huge_addr+0x2c/0xf0 >> Call Trace: >> [e5059d00] [e5059d00] 0xe5059d00 (unreliable) >> [e5059d20] [c0107510] follow_page_mask+0x40/0x3c0 >> [e5059d80] [c0107958] __get_user_pages+0xc8/0x420 >> [e5059de0] [c010817c] get_user_pages_remote+0x8c/0x230 >> [e5059e30] [c013f170] copy_strings+0x110/0x3a0 >> [e5059ea0] [c013f42c] copy_strings_kernel+0x2c/0x50 >> [e5059ec0] [c0141324] do_execveat_common+0x474/0x620 >> [e5059f10] [c01414fc] do_execve+0x2c/0x40 >> [e5059f20] [c0001f68] try_to_run_init_process+0x18/0x60 >> [e5059f30] [c000289c] kernel_init+0xcc/0x120 >> [e5059f40] [c000f1e8] ret_from_kernel_thread+0x5c/0x64 >> Instruction dump: >> bfc10018 7c9f2378 90010024 7fc000a6 7c000146 80630020 38a1000c 38c10008 >> 4bfff869 2c030000 41c20090 81210008 <81430000> 81630004 3860ffea 2f890000 >> ---[ end trace 4bf94e15fd9fa824 ]--- > > > Which code path is that. That null should be filtered by the if > (pmd_none(pmd)) check in find_linux_pte_or_hugepte right ? The crash happens when __find_linux_pte_or_hugepte() calls hugepd_ok(), on this line [1]. It's triggered when __find_linux_pte_or_hugepte() is first called, when the kernel tries to spawn the init process. The input effective address (ea arg) is bffffff1. This is the call stack: [e5059cd0] [c0017b60] __find_linux_pte_or_hugepte+0x60/0x120 (unreliable) [e5059d00] [c001832c] follow_huge_addr+0x2c/0xf0 [e5059d20] [c0107590] follow_page_mask+0x40/0x3c0 [e5059d80] [c01079d8] __get_user_pages+0xc8/0x420 [e5059de0] [c01081fc] get_user_pages_remote+0x8c/0x230 [e5059e30] [c013f210] copy_strings+0x110/0x3a0 [e5059ea0] [c013f4cc] copy_strings_kernel+0x2c/0x50 [e5059ec0] [c01413c4] do_execveat_common+0x474/0x620 [e5059f10] [c014159c] do_execve+0x2c/0x40 [e5059f20] [c0001f68] try_to_run_init_process+0x18/0x60 [e5059f30] [c000289c] kernel_init+0xcc/0x120 [e5059f40] [c000f1e8] ret_from_kernel_thread+0x5c/0x64 Thanks in advance for any pointers. [1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/mm/hugetlbpage.c#n918 --- Best Regards, Laurentiu
