Messages in this thread | | | From | Larry Finger <> | Subject | [Update] Regression in 4.18 - 32-bit PowerPC crashes on boot - bisected to commit 1d40a5ea01d5 | Date | Fri, 29 Jun 2018 15:42:12 -0500 |
| |
My PowerBook G4 Aluminum crashes on boot with 4.18-rcX kernels with a kernel BUG at include/linux/page-flags.h:700! The problem was bisected to commit 1d40a5ea01d5 ("mm: mark pages in use for page tables"). It is not possible to capture the bug with anything other than a camera. The first few lines of the traceback are as follows:
free_pgd_range+0x19c/0x30c (unreliable) free_pgtables_0xa0/0xb0 exit_pmap+0xf4/0x16c mmput+0x64/0xf0 do_exit+0x33c/0x89c oops_end+0x13c/0x144 _exception_pkey+0x58/0x128 ret_from_except_full+0x0/0x4 --- interrupt: 700 at free_pgd_range+0x19c/0x30c LR = free_pgd_range+0x19c/0x30c free_pgtables+0xa/0xb exit_mnap+0xf4/0x16c mmput+0x64/0xf0 flush_old_exec+0x490/0x550
I have more information regarding this BUG. Line 700 of page-flags.h is the macro PAGE_TYPE_OPS(Table, table). For further debugging, I manually expanded the macro, and found that the bug line is VM_BUG_ON_PAGE(!PageTable(page), page) in routine __ClearPageTable(), which is called from pgtable_page_dtor() in include/linux/mm.h. I also added a printk call to PageTable() that logs page->page_type. The routine was called twice. The first had page_type of 0xfffffbff, which would have been expected for a . The second call had 0xffffffff, which led to the BUG.
Larry
| |