Messages in this thread Patch in this message | | | Subject | Major breakage in linux-git on x86_64, oom killer goes on rampage | From | Pavel Roskin <> | Date | Thu, 04 Aug 2005 15:58:42 -0400 |
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Hello!
This fix breaks x64_64:
commit f33ea7f404e592e4563b12101b7a4d17da6558d7 tree 1d587ad8a06cb6d2e3a187f0312c8a524ffefe53 parent 5cb4cc0d8211c490537c8568001958fc76741312 author Nick Piggin <nickpiggin@yahoo.com.au> Wed, 03 Aug 2005 20:24:01 +1000 committer Linus Torvalds <torvalds@g5.osdl.org> Wed, 03 Aug 2005 09:12:05 -0700
* include/linux/mm.h, mm/memory.c:
[PATCH] fix get_user_pages bug ...
The system doesn't boot. Most processes are killed by VM.
The patch does more than it claims. It actually redefines VM_FAULT_OOM and VM_FAULT_SIGBUS. Unfortunately, a quick look at arch/x86_64/mm/fault.c shows that the return value of handle_mm_fault() is compared with numerical constants. This patch helps partly:
--- arch/x86_64/mm/fault.c +++ arch/x86_64/mm/fault.c @@ -439,15 +439,15 @@ good_area: * the fault. */ switch (handle_mm_fault(mm, vma, address, write)) { - case 1: + case VM_FAULT_MINOR: tsk->min_flt++; break; - case 2: + case VM_FAULT_MAJOR: tsk->maj_flt++; break; - case 0: + case VM_FAULT_SIGBUS: goto do_sigbus; - default: + case VM_FAULT_OOM: goto out_of_memory; } Now the system boot goes a little further and then the kernel reports a BUG in mm/memory.c:985. Apparently __handle_mm_fault() returns something unexpected. My guess is that some x86_64 specific functions return -1 and 0 when they mean VM_FAULT_SIGBUS and VM_FAULT_OOM. Returning -1 would trigger BUG(), returning 0 would be treated as VM_FAULT_OOM rather than VM_FAULT_SIGBUS. I'm not sure I'll be able to fix it quickly, but I hope the gurus will beat me at that. In the meantime, please don't make any releases unless the "commit f33ea7f404e592e4563b12101b7a4d17da6558d7" is reverted.
-- Regards, Pavel Roskin
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